Related
I am new to Javascript development.
I am trying to assign HTML elements IDs stored in an array to shorthands to be used in my function later.
So that instead of writing :
let addprop = document.querySelector(`#addprop`);
let readprop = document.querySelector(`#readprop`);
let editprop = document.querySelector(`#editprop`);
let footer = document.querySelector(`#footer`);
let association = document.querySelector(`#association`);
I can attribute elements ids that i store in an array like this :
let arrayElements = ["addprop", "readprop", "editprop", "footer", "association"] ;
arrayElements.forEach(el => { return(new Function (`${el} = document.querySelector("#${el}");`)()); });
Now, this bit of code works but from what I read here :
Execute JavaScript code stored as a string
This is probably not a good way to do it and also declares global variables.
One problem I encountered is that if I try to directly execute the assignment like this :
el = document.querySelector(`#${el}`);
Then the el value takes the value of the named access ID element (https://html.spec.whatwg.org/multipage/window-object.html#named-access-on-the-window-object) and breaks the code.
So I resorted to generate a string first then execute it.
I could simply assign each shorthand manually but I spent way too much time trying to make this work and am now left curious as to what would be a good solution or approach for this.
And would the scope limitations for loops simply forbid me to do this without using global variables ?
edit : switched the working code in one line
Possible answer :
1 - does it matter to declare global variables like that ? As these variables already exist globally because of browsers named access for elements IDs.
2 - By kiranvj's answer, a solution can be to store in an object structured as keys being the shortcuts and the full strings being the values, and calling the shortcuts with the object[key] method ; or using destructuring to assign the values to variable directly with :
const {addprop, readprop, editprop, idfooter, assocpatients} = elements;
I feel like I am missing something on this last one but it also seems to work.
In the end I will stick with my first code as condensing the function in one line seems to negate the risks of cross site scripting (?), and global values for the variables assigned though this method anyway already exist because of named access.
You can create a dictionary with all the elements with ID and then destroy it into your variables, ignoring the unused ones.
function getAllElementsWithId() {
let elements = {}
for (let el of document.querySelectorAll('[id]')) {
if (!(el.id in elements)) {
elements[el.id] = el
}
}
return elements
}
let { addprop, readprop, editprop, footer, association } = getAllElementsWithId()
This uses document.querySelectorAll (link to MDN) to get all elements with an ID. Notice that for big pages this could be a performance issue.
Also, what you would usually do is to add them into a container, in this case it seems like a dictionary.
let arrayElements = ["addprop", "readprop", "editprop", "footer", "association"]
let elementsId = Object.fromEntries(arrayElements.map(id => [id, document.getElementById(id)]))
This uses Object.fromEntries (link to MDN) to generate the dictionary. Also I'm using document.getElementById (link to MDN) instead of document.querySelector so you don't need to add the hashtag before the id.
If you are concerned about global scope, you can try something like below. Use forEach instead of map . map also work but since you are not handling the return of map, forEach would be a better choice.
let arrayElements = ["addprop", "readprop", "editprop", "footer", "association"];
let elements = {};
arrayElements.forEach(el => elements[el] = document.querySelector(`#${el}`));
// access variables like elements.ID-NAME
console.log(elements);
<div id="addprop"></div>
<div id="readprop"></div>
Object destructing can be used if you know the object key name.
example : let {addprop} = element;
Another thing which you might be interested is Automatic global variables
This means a new variable (scoped to window) with the name of element id is created for all the elements in page. See the html5 spec. I would not recommend using it though.
So you don't have to call like document.querySelector('addprop')
addprop variable will have the DOM object.
See this example
// these works due to automatic global varaibles binding
alert(addprop);
console.log(addprop);
<div id="addprop">Some contents</div>
Has a best-practice around using setAttribute instead of the dot (.) attribute notation been developed?
E.g.:
myObj.setAttribute("className", "nameOfClass");
myObj.setAttribute("id", "someID");
or
myObj.className = "nameOfClass";
myObj.id = "someID";
From Javascript: The Definitive Guide, it clarifies things. It notes that HTMLElement objects of a HTML doc define JS properties that correspond to all standard HTML attributes.
So you only need to use setAttribute for non-standard attributes.
Example:
node.className = 'test'; // works
node.frameborder = '0'; // doesn't work - non standard attribute
node.setAttribute('frameborder', '0'); // works
None of the previous answers are complete and most contain misinformation.
There are three ways of accessing the attributes of a DOM Element in JavaScript. All three work reliably in modern browsers as long as you understand how to utilize them.
1. element.attributes
Elements have a property attributes that returns a live NamedNodeMap of Attr objects. The indexes of this collection may be different among browsers. So, the order is not guaranteed. NamedNodeMap has methods for adding and removing attributes (getNamedItem and setNamedItem, respectively).
Notice that though XML is explicitly case sensitive, the DOM spec calls for string names to be normalized, so names passed to getNamedItem are effectively case insensitive.
Example Usage:
var div = document.getElementsByTagName('div')[0];
//you can look up specific attributes
var classAttr = div.attributes.getNamedItem('CLASS');
document.write('attributes.getNamedItem() Name: ' + classAttr.name + ' Value: ' + classAttr.value + '<br>');
//you can enumerate all defined attributes
for(var i = 0; i < div.attributes.length; i++) {
var attr = div.attributes[i];
document.write('attributes[] Name: ' + attr.name + ' Value: ' + attr.value + '<br>');
}
//create custom attribute
var customAttr = document.createAttribute('customTest');
customAttr.value = '567';
div.attributes.setNamedItem(customAttr);
//retreive custom attribute
customAttr = div.attributes.getNamedItem('customTest');
document.write('attributes.getNamedItem() Name: ' + customAttr.name + ' Value: ' + customAttr.value + '<br>');
<div class="class1" id="main" data-test="stuff" nonStandard="1234"></div>
2. element.getAttribute & element.setAttribute
These methods exist directly on the Element without needing to access attributes and its methods but perform the same functions.
Again, notice that string name are case insensitive.
Example Usage:
var div = document.getElementsByTagName('div')[0];
//get specific attributes
document.write('Name: class Value: ' + div.getAttribute('class') + '<br>');
document.write('Name: ID Value: ' + div.getAttribute('ID') + '<br>');
document.write('Name: DATA-TEST Value: ' + div.getAttribute('DATA-TEST') + '<br>');
document.write('Name: nonStandard Value: ' + div.getAttribute('nonStandard') + '<br>');
//create custom attribute
div.setAttribute('customTest', '567');
//retreive custom attribute
document.write('Name: customTest Value: ' + div.getAttribute('customTest') + '<br>');
<div class="class1" id="main" data-test="stuff" nonStandard="1234"></div>
3. Properties on the DOM object, such as element.id
Many attributes can be accessed using convenient properties on the DOM object. Which properties exist on a given object depends on the object's DOM node type, regardless of which attributes are specified in the HTML. The available properties are defined somewhere in the prototype chain of DOM object in question. So, the specific properties that are defined will depend on the type of Element you are accessing.
For example, className and id are defined on Element and exist on all DOM nodes that are elements, but not text or comment nodes. value is more narrowly defined. It only available on HTMLInputElement and it's descendants.
Notice that JavaScript properties are case sensitive. Although most properties will use lowercase, some are camelCase. So always check the spec to be sure.
This "chart" captures a portion of the prototype chain for these DOM objects. It's not even close to complete, but it demonstrates the overall structure.
____________Node___________
| | |
Element Text Comment
| |
HTMLElement SVGElement
| |
HTMLInputElement HTMLSpanElement
Example Usage:
var div = document.getElementsByTagName('div')[0];
//get specific attributes
document.write('Name: class Value: ' + div.className + '<br>');
document.write('Name: id Value: ' + div.id + '<br>');
document.write('Name: ID Value: ' + div.ID + '<br>'); //undefined
document.write('Name: data-test Value: ' + div.dataset.test + '<br>'); //.dataset is a special case
document.write('Name: nonStandard Value: ' + div.nonStandard + '<br>'); //undefined
<div class="class1" id="main" data-test="stuff" nonStandard="1234"></div>
Caveat: This is an explanation of how the HTML spec define attributes and how modern, evergreen browsers handle them. There certainly are old browsers (IE, Netscape, etc.) that didn't adhere to or even predated the spec. If you need to support old ancient (broken) browsers, you'll need more information than provided here.
You should always use the direct .attribute form (but see the quirksmode link below) if you want programmatic access in JavaScript. It should handle the different types of attributes (think "onload") correctly.
Use getAttribute/setAttribute when you wish to deal with the DOM as it is (e.g. literal text only). Different browsers confuse the two. See Quirks modes: attribute (in)compatibility.
One case I found where setAttribute is necessary is when changing ARIA attributes, since there are no corresponding properties. For example
x.setAttribute('aria-label', 'Test');
x.getAttribute('aria-label');
There's no x.arialabel or anything like that, so you have to use setAttribute.
Edit: x["aria-label"] does not work. You really do need setAttribute.
x.getAttribute('aria-label')
null
x["aria-label"] = "Test"
"Test"
x.getAttribute('aria-label')
null
x.setAttribute('aria-label', 'Test2')
undefined
x["aria-label"]
"Test"
x.getAttribute('aria-label')
"Test2"
These answers aren't really addressing the large confusion with between properties and attributes. Also, depending on the Javascript prototype, sometimes you can use a an element's property to access an attributes and sometimes you can't.
First, you have to remember that an HTMLElement is a Javascript object. Like all objects, they have properties. Sure, you can create a property called nearly anything you want inside HTMLElement, but it doesn't have to do anything with the DOM (what's on the page). The dot notation (.) is for properties. Now, there some special properties that are mapped to attributes, and at the time or writing there are only 4 that are guaranteed (more on that later).
All HTMLElements include a property called attributes. HTMLElement.attributes is a live NamedNodeMap Object that relates to the elements in the DOM. "Live" means that when the node changes in the DOM, they change on the JavaScript side, and vice versa. DOM attributes, in this case, are the nodes in question. A Node has a .nodeValue property that you can change. NamedNodeMap objects have a function called setNamedItem where you can change the entire node. You can also directly access the node by the key. For example, you can say .attributes["dir"] which is the same as .attributes.getNamedItem('dir'); (Side note, NamedNodeMap is case-insensitive, so you can also pass 'DIR');
There's a similar function directly in HTMLElement where you can just call setAttribute which will automatically create a node if it doesn't exist and set the nodeValue. There are also some attributes you can access directly as properties in HTMLElement via special properties, such as dir. Here's a rough mapping of what it looks like:
HTMLElement {
attributes: {
setNamedItem: function(attr, newAttr) {
this[attr] = newAttr;
},
getNamedItem: function(attr) {
return this[attr];
},
myAttribute1: {
nodeName: 'myAttribute1',
nodeValue: 'myNodeValue1'
},
myAttribute2: {
nodeName: 'myAttribute2',
nodeValue: 'myNodeValue2'
},
}
setAttribute: function(attr, value) {
let item = this.attributes.getNamedItem(attr);
if (!item) {
item = document.createAttribute(attr);
this.attributes.setNamedItem(attr, item);
}
item.nodeValue = value;
},
getAttribute: function(attr) {
return this.attributes[attr] && this.attributes[attr].nodeValue;
},
dir: // Special map to attributes.dir.nodeValue || ''
id: // Special map to attributes.id.nodeValue || ''
className: // Special map to attributes.class.nodeValue || ''
lang: // Special map to attributes.lang.nodeValue || ''
}
So you can change the dir attributes 6 ways:
// 1. Replace the node with setNamedItem
const newAttribute = document.createAttribute('dir');
newAttribute.nodeValue = 'rtl';
element.attributes.setNamedItem(newAttribute);
// 2. Replace the node by property name;
const newAttribute2 = document.createAttribute('dir');
newAttribute2.nodeValue = 'rtl';
element.attributes['dir'] = newAttribute2;
// OR
element.attributes.dir = newAttribute2;
// 3. Access node with getNamedItem and update nodeValue
// Attribute must already exist!!!
element.attributes.getNamedItem('dir').nodeValue = 'rtl';
// 4. Access node by property update nodeValue
// Attribute must already exist!!!
element.attributes['dir'].nodeValue = 'rtl';
// OR
element.attributes.dir.nodeValue = 'rtl';
// 5. use setAttribute()
element.setAttribute('dir', 'rtl');
// 6. use the UNIQUELY SPECIAL dir property
element["dir"] = 'rtl';
element.dir = 'rtl';
You can update all properties with methods #1-5, but only dir, id, lang, and className with method #6.
Extensions of HTMLElement
HTMLElement has those 4 special properties. Some elements are extended classes of HTMLElement have even more mapped properties. For example, HTMLAnchorElement has HTMLAnchorElement.href, HTMLAnchorElement.rel, and HTMLAnchorElement.target. But, beware, if you set those properties on elements that do not have those special properties (like on a HTMLTableElement) then the attributes aren't changed and they are just, normal custom properties. To better understand, here's an example of its inheritance:
HTMLAnchorElement extends HTMLElement {
// inherits all of HTMLElement
href: // Special map to attributes.href.nodeValue || ''
target: // Special map to attributes.target.nodeValue || ''
rel: // Special map to attributes.ref.nodeValue || ''
}
Custom Properties
Now the big warning: Like all Javascript objects, you can add custom properties. But, those won't change anything on the DOM. You can do:
const newElement = document.createElement('div');
// THIS WILL NOT CHANGE THE ATTRIBUTE
newElement.display = 'block';
But that's the same as
newElement.myCustomDisplayAttribute = 'block';
This means that adding a custom property will not be linked to .attributes[attr].nodeValue.
Performance
I've built a jsperf test case to show the difference: https://jsperf.com/set-attribute-comparison. Basically, In order:
Custom properties because they don't affect the DOM and are not attributes.
Special mappings provided by the browser (dir, id, className).
If attributes already exists, element.attributes.ATTRIBUTENAME.nodeValue =
setAttribute();
If attributes already exists, element.attributes.getNamedItem(ATTRIBUTENAME).nodeValue = newValue
element.attributes.ATTRIBUTENAME = newNode
element.attributes.setNamedItem(ATTRIBUTENAME) = newNode
Conclusion (TL;DR)
Use the special property mappings from HTMLElement: element.dir, element.id, element.className, or element.lang.
If you are 100% sure the element is an extended HTMLElement with a special property, use that special mapping. (You can check with if (element instanceof HTMLAnchorElement)).
If you are 100% sure the attribute already exists, use element.attributes.ATTRIBUTENAME.nodeValue = newValue.
If not, use setAttribute().
"When to use setAttribute vs .attribute= in JavaScript?"
A general rule is to use .attribute and check if it works on the browser.
..If it works on the browser, you're good to go.
..If it doesn't, use .setAttribute(attribute, value) instead of .attribute for that attribute.
Rinse-repeat for all attributes.
Well, if you're lazy you can simply use .setAttribute. That should work fine on most browsers. (Though browsers that support .attribute can optimize it better than .setAttribute(attribute, value).)
Interesting observation from Google API script regarding this:
They do it like this:
var scriptElement = document.createElement("script");
scriptElement = setAttribute("src", "https://some.com");
scriptElement = setAttribute("nonce", "https://some.com");
scriptElement.async = "true";
Notice, how they use setAttribute for "src" and "nonce", but then .async = ... for "async" attribute.
I'm not 100% sure, but probably that's because "async" is only supported on browsers that support direct .attr = assignment. So, there's no sense trying to setAttribute("async") because if browser doesn't understand .async=... - it will not understand "async" attribute.
Hopefully, that's a helpful insight from my ongoing "Un-minify GAPI" research project. Correct me if I'm wrong.
This looks like one case where it is better to use setAttribute:
Dev.Opera — Efficient JavaScript
var posElem = document.getElementById('animation');
var newStyle = 'background: ' + newBack + ';' +
'color: ' + newColor + ';' +
'border: ' + newBorder + ';';
if(typeof(posElem.style.cssText) != 'undefined') {
posElem.style.cssText = newStyle;
} else {
posElem.setAttribute('style', newStyle);
}
methods for setting attributes(for example class) on an element:
1. el.className = string
2. el.setAttribute('class',string)
3. el.attributes.setNamedItem(object)
4. el.setAttributeNode(node)
I have made a simple benchmark test (here)
and it seems that setAttributeNode is about 3 times faster then using setAttribute.
so if performance is an issue - use "setAttributeNode"
This is very good discussion. I had one of those moments when I wished or lets say hoped (successfully that I might add) to reinvent the wheel be it a square one.
Any ways above is good discussion, so any one coming here looking for what is the difference between Element property and attribute. here is my penny worth and I did have to find it out hard way. I would keep it simple so no extraordinary tech jargon.
suppose we have a variable calls 'A'. what we are used to is as following.
Below will throw an error because simply it put its is kind of object that can only have one property and that is singular left hand side = singular right hand side object. Every thing else is ignored and tossed out in bin.
let A = 'f';
A.b =2;
console.log(A.b);
who has decided that it has to be singular = singular. People who make JavaScript and html standards and thats how engines work.
Lets change the example.
let A = {};
A.b =2;
console.log(A.b);
This time it works ..... because we have explicitly told it so and who decided we can tell it in this case but not in previous case. Again people who make JavaScript and html standards.
I hope we are on this lets complicate it further
let A = {};
A.attribute ={};
A.attribute.b=5;
console.log(A.attribute.b); // will work
console.log(A.b); // will not work
What we have done is tree of sorts level 1 then sub levels of non-singular object. Unless you know what is where and and call it so it will work else no.
This is what goes on with HTMLDOM when its parsed and painted a DOm tree is created for each and every HTML ELEMENT. Each has level of properties per say. Some are predefined and some are not. This is where ID and VALUE bits come on.
Behind the scene they are mapped on 1:1 between level 1 property and sun level property aka attributes. Thus changing one changes the other. This is were object getter ans setter scheme of things plays role.
let A = {
attribute :{
id:'',
value:''
},
getAttributes: function (n) {
return this.attribute[n];
},
setAttributes: function (n,nn){
this.attribute[n] = nn;
if(this[n]) this[n] = nn;
},
id:'',
value:''
};
A.id = 5;
console.log(A.id);
console.log(A.getAttributes('id'));
A.setAttributes('id',7)
console.log(A.id);
console.log(A.getAttributes('id'));
A.setAttributes('ids',7)
console.log(A.ids);
console.log(A.getAttributes('ids'));
A.idsss=7;
console.log(A.idsss);
console.log(A.getAttributes('idsss'));
This is the point as shown above ELEMENTS has another set of so called property list attributes and it has its own main properties. there some predefined properties between the two and are mapped as 1:1 e.g. ID is common to every one but value is not nor is src. when the parser reaches that point it simply pulls up dictionary as to what to when such and such are present.
All elements have properties and attributes and some of the items between them are common. What is common in one is not common in another.
In old days of HTML3 and what not we worked with html first then on to JS. Now days its other way around and so has using inline onlclick become such an abomination. Things have moved forward in HTML5 where there are many property lists accessible as collection e.g. class, style. In old days color was a property now that is moved to css for handling is no longer valid attribute.
Element.attributes is sub property list with in Element property.
Unless you could change the getter and setter of Element property which is almost high unlikely as it would break hell on all functionality is usually not writable off the bat just because we defined something as A.item does not necessarily mean Js engine will also run another line of function to add it into Element.attributes.item.
I hope this gives some headway clarification as to what is what.
Just for the sake of this I tried Element.prototype.setAttribute with custom function it just broke loose whole thing all together, as it overrode native bunch of functions that set attribute function was playing behind the scene.
Adding 2 more points related to .textContent and .innerHTML
<div id="mydiv"></div>
var elem = document.getElementById("mydiv");
elem.textContent = "hello"; // OK - Content has been updated
elem.setAttribute("textContent", "hello"); // NOT OK - You are trying to set
// the attribute than it's content
elem.innerHTML = "world"; // OK - Content has been updated
elem.setAttribute("innerHTML", "world"); // NOT OK - You are trying to set
// the attribute than it's content
One difference between the two is that setAttribute, when used to set the value of an <input/> will make that the default value when you call .reset() on the form it's part of, but .value = will not do this.
https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement/reset
Note that if setAttribute() is called to set the value of a particular attribute, a subsequent call to reset() won’t reset the attribute to its default value, but instead will keep the attribute at whatever value the setAttribute() call set it to.
If the element you are referring to does not already include a Javascript object property for a given attribute (as others have described), then setting that property will not propagate the change back to the DOM, it just adds the named property to the Javascript object, and the DOM ignores it. For example, getting the element mySpan by id and then doing mySpan.class = 'warning' will do nothing, whether or not the span element in question already has a class attribute defined, because mySpan.class is not defined in the Javascript object for a span element. You have to use mySpan.setAttribute('class', 'warning').
However a second nuance is that setting the Javascript object's innerHTML property using mySpan.setAttribute("innerHTML", someHTML) does not update the content of the element. I don't know how Javascript even catches mySpan.innerHTML = something, and calls the HTML parser, but there's some magic going on under the hood.
I'm trying to create the following element nodetree:
<v:custProps>
<v:cp v:nameU="Cost">
</v:custProps>
with:
newCustprop = document.createElement("v:custProps");
newcp = document.createElement("v:cp");
newcp.setAttribute("v:nameU", "Cost");
newCustprop.appendChild(newcp);
However, document.createElement("v:custProps") generates <v:custprops> as opposed to <v:custProps>. Is there anyway to escape this parsing?
Edit 1:
I'm currently reading this article on nodename case sensitivity. It's slightly irrelevant to my problem though because my code is unparsed with <![CDATA]]> and I'd rather not use .innerHTML.
You need to use createElementNS()/setAttributeNS() and provide the namespace, not only the alias/prefix. The example uses urn:v as namespace.
var xmlns_v = "urn:v";
var newCustprop = document.createElementNS(xmlns_v, "v:custProps");
var newcp = document.createElementNS(xmlns_v, "v:cp");
newcp.setAttributeNS(xmlns_v, "v:nameU", "Cost");
newCustprop.appendChild(newcp);
var xml = (new XMLSerializer).serializeToString(newCustprop);
xml:
<v:custProps xmlns:v="urn:v"><v:cp v:nameU="Cost"/></v:custProps>
It's not recommended to use document.createElement for qualified names. See if the document.createElementNS can better serve your purposes.
I still had issues where createElementNs would attach an attribute of "xmls" on my string about using new XMLSerializer().serializeToString(xmlDoc).
I ended up using the following function to create elements with case sensitive tag names:
function createElement(tagName) {
const doc = new DOMParser().parseFromString(`<${tagName}></${tagName}>`, 'text/xml')
return doc.children[0]
}
I am finding that, for my purposes, XML namespaces are simply causing much headache and are completely unnecessary. (For example, how they complicate xpath.)
Is there a simple way to remove namespaces entirely from an XML document?
(There is a related question, but it deals with removing namespace prefixes on tags, rather than namespace declarations from the document root: "Easy way to drop XML namespaces with javascript".)
Edit: Samples and more detail below:
XML:
<?xml version="1.0" ?>
<main xmlns="example.com">
<primary>
<enabled>true</enabled>
</primary>
<secondary>
<enabled>false</enabled>
</secondary>
</main>
JavaScript:
function useHttpResponse()
{
if (http.readyState == 4)
{
if(http.status == 200)
{
var xml = http.responseXML;
var evalue = getXMLValueByPath('/main/secondary/enabled', xml);
alert(evalue);
}
}
}
function getXMLValueByPath(nodepath, xml)
{
var result = xml.evaluate(nodepath, xml, null, XPathResult.STRING_TYPE, null).stringValue;
return result;
}
The sample XML is just like the actual one I am working with, albeit much shorter. Notice that there are no prefixes on the tags for the namespace. I assume this is the null or default namespace.
The JavaScript is a snippet from my ajax functions. If I remove the xmlns="example.com" portion from the main tag, I am able to successfully get the value. As long as any namespace is present, the value becomes undefined.
Edit 2:
It may be worth mentioning that none of the declared namespaces are actually used in the XML tags (like the sample above). In the actual XML file I am working with, three namespaces are declared, but no tags are prefixed with a namespace reference. Thus, perhaps the question should be re-titled, "How to remove unused XML namespaces using Javascript?" I do not see the reason to retain a namespace if it is 1) never used and 2) complicating an otherwise simple path to a node using xpath.
This should remove any namespace declaration you find:
var xml = http.responseXML.replace(/<([a-zA-Z0-9 ]+)(?:xml)ns=\".*\"(.*)>/g, "<$1$2>");
Inorder to replace all the xmlns attributes from an XML javascript string
you can try the following regex
xmlns=\"(.*?)\"
NB: This regex can be used to replace any attributes
var str = `<?xml version="1.0" ?>
<main xmlns="example.com">
<primary>
<enabled>true</enabled>
</primary>
<secondary>
<enabled>false</enabled>
</secondary>
</main>`;
str = str.replace(/xmlns=\"(.*?)\"/g, '');
console.log(str)
Approach without using regex (This removes attributes also)
let xml = '';//input
let doc = new DOMParser().parseFromString(xml,"text/xml");
var root=doc.firstElementChild;
var newdoc = new Document();
newdoc.appendChild(removeNameSpace(root));
function removeNameSpace (root){
let parentElement = document.createElement(root.localName);
let nodeChildren = root.childNodes;
for (let i = 0; i <nodeChildren.length; i++) {
let node = nodeChildren[i];
if(node.nodeType == 1){
let child
if(node.childElementCount!=0)
child = removeNameSpace(node);
else{
child = document.createElement(node.localName);
let textNode = document.createTextNode(node.innerHTML);
child.append(textNode);
}
parentElement.append(child);
}
}
return parentElement;
}
Let's say I'm generating markup through server-side code. I'm generating a bunch of HTML tags but I want to add custom client-side behavior.
With JavaScript (if I had a reference to the DOM node) I could have written:
var myDOMNode = ...
myDOMNode.myCustomAttribute = "Hi!";
Now the issue here is that I don't want to qualify every element with an unique id just to initialize data. And it's really strange to me, that there's not an easier and unobtrusive way to attach client-side behavior.
If I'm remembing this correctly, this is valid IE stuff.
<div onload="this.myCustomAttribute='Hi!'"></div>
If I was able to do this, I should be able to access it's "data context" though the identifier 'myCustomAttribute', which is really what I want.
The following will work but not validate:
<div myattribute="myvalue"></div>
But if you are injecting it into the HTML with Javascript, then perhaps that's not concern for you. Otherwise, you can use something like jQuery to process the elements before adding them to the DOM:
$(elements).each(function(){
$(this).attr('myattribute','myvalue');
});
First off you should access custom attributes using the getAttribute and setAttribute methods if you want your code to work on other browsers than IE.
As to your event handler question that really depends on how you add the event handler.
Assigning a function directly to the elements onXXXX property would allow you access the the element via this.
If you use IE's attachEvent you can't use this, you can access the element that generated the event using event.srcElementbut that may be child element of the div. Hence you will need to test for the existance of myCustomAttribute and search up the ancestors until you find it.
I do appricate the input but I've finally figured this out and it's the way I go about initialization that has been the thorn in my side.
What you never wan't do is to pollute your global namespace with a bunch of short lived identifiers. Any time you put id="" on an element you're doing exactly that (same thing for any top level function). By relying on jQuery, HTML5 data and CSS there's a solution to my problem which I think is quite elegant.
What I do is that I reserve a CSS class for a specific behavior and then use HTML5 data to parameterize the behavior. When the document is ready, I query the document (using Query) for the CSS class that represents the behavior and initialize the client-side behavior.
I've been doing a lot of ASP.NET and within this context both the id="" and name="" belongs to ASP.NET and is pretty useless for anything else than internal ASP.NET stuff. What you typically find yourself doing is to get at a server-side property called ClientID you can refer to this from client-side JavaScript, it's a lot of hassle. They made it easier in 4.0 but fundamentally I think it's pretty much broken.
Using this hybrid of CSS, HTML5 data and jQuery solves this problem altogether. Here's an example of an attached behavior that uses regular expressions to validate the input of a textbox.
<input type="text" class="-input-regex" data-regex="^[a-z]+$" />
And here's the script:
$(function () {
function checkRegex(inp) {
if (inp.data("regex").test(inp.val()))
inp.data("good-value", inp.val());
else
inp.val(inp.data("good-value"));
}
$(".-input-regex")
.each(function () {
// starting with jQuery 1.5
// you can get at HTML5 data like this
var inp = $(this);
var pattern = inp.data("regex");
inp.data("regex", new RegExp(pattern));
checkRegex(inp);
})
.keyup(function (e) {
checkRegex($(this));
})
.change(function (e) {
checkRegex($(this));
})
.bind("paste", undefined, function (e) {
checkRegex($(this));
})
;
});
Totally clean, no funky id="" or obtrusive dependency.
In HTML5 there are HTML5 data attributes introduced exactly for the case.
<!DOCTYPE html>
<div data-my-custom-attribute='Hi!'></div>
is now corect, validating html. You can use any name starting with data- in any quantity.
There is jQuery .data method for interaction with them. Use .data( key ) to get, .data(key, value) to set data-key attribute. For example,
$('div').each(function () {
$(this).html($(this).data('myCustomAttribute')).data('processed', 'OK');
});
How about this?
<script>
function LoadElement(myDiv)
{
alert(this.myCustomAttribute);
}
</script>
<div onload="LoadElement(this)"></div>
not tested btw
Since you're trying to do this for multiple elements, you may try name attributes and getElementsByName.
<div name="handleonload">...</div>
window.onload = function () {
var divs = document.getElementsByName('handleonload');
for (var i = 0; i < divs.length; i += 1) {
divs[i].foo = 'bar';
}
};
Alternatively, you can use selectors, using libraries (such as jQuery and Prototype) and their respective iterators. This will also allow for you to search by other attributes (such as class).
Though, be cautious with your terminology:
obj.property = value;
<tag attribute="value">
<div style="width:100px;height:100px;border:solid black 1px" myCustomAttribute='Hi!' onclick="alert(myCustomAttribute);"></div>
The onload event is used for server side events. Its not part of the standard html element events.
Take a look at the following functions (especially the walk_the_dom one):
// walk_the_DOM visits every node of the tree in HTML source order, starting
// from some given node. It invokes a function,
// passing it each node in turn. walk_the_DOM calls
// itself to process each of the child nodes.
var walk_the_DOM = function walk(node, func) {
func(node);
node = node.firstChild;
while (node) {
walk(node, func);
node = node.nextSibling;
}
};
// getElementsByAttribute takes an attribute name string and an optional
// matching value. It calls walk_the_DOM, passing it a
// function that looks for an attribute name in the
// node. The matching nodes are accumulated in a
// results array.
var getElementsByAttribute = function (att, value) {
var results = [];
walk_the_DOM(document.body, function (node) {
var actual = node.nodeType === 1 && node.getAttribute(att);
if (typeof actual === 'string' &&
(actual === value || typeof value !== 'string')) {
results.push(node);
}
});
return results;
};
With the above two functions at hand, now we can do something like this:
some link
<script>
var els = getElementsByAttribute('dreas');
if (els.length > 0) {
els[0].innerHTML = 'changed text';
}
</script>
Notice how now I am making finding that particular element (which has an attribute called dreas) without using an id or a class name...or even a tag name
Looks like jQuery is the best bet for this one based on my searching. You can bind an object to a DOM node by:
var domNode = ...
var myObject = { ... }
$(domNode).data('mydata', mymyObj);
then you can call the data back up the same way, using your key.
var myObect = $(domNode).data('mydata');
I assume you could also store a reference to this within this object, but that may be more info then you really want. Hope I could help.