Two questions ... I want to use the object tag to embed an html file that uses external style sheets ... however, nothing that I have tried works. The first question is how to that? ... note: the style sheets are linked to both documents.
The second question is how to determine and set the height attribute of the object so as to eliminate scrollbars ...
The object tag is inside the folllowing DIV ...
In IE8, I simply call "ScrollHeightValue('SF_010A','SF_010B')" ... which are the ids of the object tag and the body of the document being embedded.
function ScrollHeightValue(a, b) {
var testObject1 = document.getElementById(a);
var testObject = testObject1.getElementById(b);
testObject1.style.height = testObject.scrollHeight + 'px';
}
Thus, the second question really is ... how do I do this for non-IE browsers?
I'm a novice ... maybe I'm not asking the questions correctly ... just want to know hoe to detetmine the height of the object so that the content of the object is visible ... without the scrollbars.
Thanks,
Bob
Answer to question number one:
To embed external HTML files in your page, use iframes, not "object".
Answer to question number two:
To get the total height of a DOM element, use its scrollHeight property. However, this property has been reported to be off by 5px for IE 8.
Try https://developer.mozilla.org/en/DOM/window.getComputedStyle
If you want to embed a HTML document in another, you must use an iframe, not an object.
Related
In tutorials I've learnt to use document.write. Now I understand that by many this is frowned upon. I've tried print(), but then it literally sends it to the printer.
So what are alternatives I should use, and why shouldn't I use document.write? Both w3schools and MDN use document.write.
The reason that your HTML is replaced is because of an evil JavaScript function: document.write().
It is most definitely "bad form." It only works with webpages if you use it on the page load; and if you use it during runtime, it will replace your entire document with the input. And if you're applying it as strict XHTML structure it's not even valid code.
the problem:
document.write writes to the document stream. Calling document.write on a closed (or loaded) document automatically calls document.open which will clear the document.
-- quote from the MDN
document.write() has two henchmen, document.open(), and document.close(). When the HTML document is loading, the document is "open". When the document has finished loading, the document has "closed". Using document.write() at this point will erase your entire (closed) HTML document and replace it with a new (open) document. This means your webpage has erased itself and started writing a new page - from scratch.
I believe document.write() causes the browser to have a performance decrease as well (correct me if I am wrong).
an example:
This example writes output to the HTML document after the page has loaded. Watch document.write()'s evil powers clear the entire document when you press the "exterminate" button:
I am an ordinary HTML page. I am innocent, and purely for informational purposes. Please do not <input type="button" onclick="document.write('This HTML page has been succesfully exterminated.')" value="exterminate"/>
me!
the alternatives:
.innerHTML This is a wonderful alternative, but this attribute has to be attached to the element where you want to put the text.
Example: document.getElementById('output1').innerHTML = 'Some text!';
.createTextNode() is the alternative recommended by the W3C.
Example: var para = document.createElement('p');
para.appendChild(document.createTextNode('Hello, '));
NOTE: This is known to have some performance decreases (slower than .innerHTML). I recommend using .innerHTML instead.
the example with the .innerHTML alternative:
I am an ordinary HTML page.
I am innocent, and purely for informational purposes.
Please do not
<input type="button" onclick="document.getElementById('output1').innerHTML = 'There was an error exterminating this page. Please replace <code>.innerHTML</code> with <code>document.write()</code> to complete extermination.';" value="exterminate"/>
me!
<p id="output1"></p>
Here is code that should replace document.write in-place:
document.write=function(s){
var scripts = document.getElementsByTagName('script');
var lastScript = scripts[scripts.length-1];
lastScript.insertAdjacentHTML("beforebegin", s);
}
You can combine insertAdjacentHTML method and document.currentScript property.
The insertAdjacentHTML() method of the Element interface parses the specified text as HTML or XML and inserts the resulting nodes into the DOM tree at a specified position:
'beforebegin': Before the element itself.
'afterbegin': Just inside the element, before its first child.
'beforeend': Just inside the element, after its last child.
'afterend': After the element itself.
The document.currentScript property returns the <script> element whose script is currently being processed. Best position will be beforebegin — new HTML will be inserted before <script> itself. To match document.write's native behavior, one would position the text afterend, but then the nodes from consecutive calls to the function aren't placed in the same order as you called them (like document.write does), but in reverse. The order in which your HTML appears is probably more important than where they're place relative to the <script> tag, hence the use of beforebegin.
document.currentScript.insertAdjacentHTML(
'beforebegin',
'This is a document.write alternative'
)
As a recommended alternative to document.write you could use DOM manipulation to directly query and add node elements to the DOM.
Just dropping a note here to say that, although using document.write is highly frowned upon due to performance concerns (synchronous DOM injection and evaluation), there is also no actual 1:1 alternative if you are using document.write to inject script tags on demand.
There are a lot of great ways to avoid having to do this (e.g. script loaders like RequireJS that manage your dependency chains) but they are more invasive and so are best used throughout the site/application.
I fail to see the problem with document.write. If you are using it before the onload event fires, as you presumably are, to build elements from structured data for instance, it is the appropriate tool to use. There is no performance advantage to using insertAdjacentHTML or explicitly adding nodes to the DOM after it has been built. I just tested it three different ways with an old script I once used to schedule incoming modem calls for a 24/7 service on a bank of 4 modems.
By the time it is finished this script creates over 3000 DOM nodes, mostly table cells. On a 7 year old PC running Firefox on Vista, this little exercise takes less than 2 seconds using document.write from a local 12kb source file and three 1px GIFs which are re-used about 2000 times. The page just pops into existence fully formed, ready to handle events.
Using insertAdjacentHTML is not a direct substitute as the browser closes tags which the script requires remain open, and takes twice as long to ultimately create a mangled page. Writing all the pieces to a string and then passing it to insertAdjacentHTML takes even longer, but at least you get the page as designed. Other options (like manually re-building the DOM one node at a time) are so ridiculous that I'm not even going there.
Sometimes document.write is the thing to use. The fact that it is one of the oldest methods in JavaScript is not a point against it, but a point in its favor - it is highly optimized code which does exactly what it was intended to do and has been doing since its inception.
It's nice to know that there are alternative post-load methods available, but it must be understood that these are intended for a different purpose entirely; namely modifying the DOM after it has been created and memory allocated to it. It is inherently more resource-intensive to use these methods if your script is intended to write the HTML from which the browser creates the DOM in the first place.
Just write it and let the browser and interpreter do the work. That's what they are there for.
PS: I just tested using an onload param in the body tag and even at this point the document is still open and document.write() functions as intended. Also, there is no perceivable performance difference between the various methods in the latest version of Firefox. Of course there is a ton of caching probably going on somewhere in the hardware/software stack, but that's the point really - let the machine do the work. It may make a difference on a cheap smartphone though. Cheers!
The question depends on what you are actually trying to do.
Usually, instead of doing document.write you can use someElement.innerHTML or better, document.createElement with an someElement.appendChild.
You can also consider using a library like jQuery and using the modification functions in there: http://api.jquery.com/category/manipulation/
This is probably the most correct, direct replacement: insertAdjacentHTML.
Try to use getElementById() or getElementsByName() to access a specific element and then to use innerHTML property:
<html>
<body>
<div id="myDiv1"></div>
<div id="myDiv2"></div>
</body>
<script type="text/javascript">
var myDiv1 = document.getElementById("myDiv1");
var myDiv2 = document.getElementById("myDiv2");
myDiv1.innerHTML = "<b>Content of 1st DIV</b>";
myDiv2.innerHTML = "<i>Content of second DIV element</i>";
</script>
</html>
Use
var documentwrite =(value, method="", display="")=>{
switch(display) {
case "block":
var x = document.createElement("p");
break;
case "inline":
var x = document.createElement("span");
break;
default:
var x = document.createElement("p");
}
var t = document.createTextNode(value);
x.appendChild(t);
if(method==""){
document.body.appendChild(x);
}
else{
document.querySelector(method).appendChild(x);
}
}
and call the function based on your requirement as below
documentwrite("My sample text"); //print value inside body
documentwrite("My sample text inside id", "#demoid", "block"); // print value inside id and display block
documentwrite("My sample text inside class", ".democlass","inline"); // print value inside class and and display inline
I'm not sure if this will work exactly, but I thought of
var docwrite = function(doc) {
document.write(doc);
};
This solved the problem with the error messages for me.
Inserting dynamic SVG content into the DOM does not work as expected, having the SVG element onload attribute (containing JavaScript) regarding: "setInterval()".
As noted in the search tags of this question; this is plain (valilla) JavaScript (not jQuery); here's a breakdown of the issue:
I have some SVG code (plain text) that gets inserted into a <div> as innerHTML
the SVG element has an onload attribute with some JavaScript inside it
the JavaScript contains setInterval(...) - (which does not work at all)
I grab the SVG element from the temporary div and return it as the result of a function.
this result is appended into some element in the live DOM (body)
the strange issue:
any other code inside that onload attribute works fine,
only setInterval & setTimeout is completely ignored
More info:
During runtime (start-up), the SVG code is grabbed from an existing embed element .getSVGDocument() (after it has loaded) and prepared as plain HTML which can just be used as a template to create many others from the same source-code. I'm not using cloneNode(true) -because: the interval is for animation (continuous slow & smooth rotation) - which could have a heavy impact on client-side resources, hence, I thought it best to grab the code and keep it as template - then remove the original from the DOM.
With all the above in mind, everything works fine:
The (new) SVG shows up on screen, all nice and dandy-like
When I console.log the (inline) SVG code that is used, all looks perfect
I get no errors, and there is no error handler that mutes errors (window.onerror == null)
The JavaScript (text) inside the SVG node's onload attribute works for things like: console.log(this) - (which produces the SVG element in the log) - however, as mentioned: setInterval() & setTimeout() is just simply ignored - without any error and no warning.
The following code is a very short example, and (regrettably) it works; however, in my production app it doesn't.
The code:
var html = '<svg xmlns="http://www.w3.org/2000/svg" version="1.1" onload="setInterval(function(){ console.log(\'testing\'); },500);">';
var temp = document.createElement('div'); temp.innerHTML = html;
var node = temp.getElementsByTagName('svg')[0];
document.body.appendChild(node);
If you test the above code in a new js file, it works; however, for the life of me I can't find the reason why it breaks in my app; as explained, it's quite simple really.
The question:
Does anyone know if there is some "gotcha" I'm not aware of regarding this? Maybe name-spacing?
If the source-code is required, I can load it up on JSFiddle, or CodePen -if required, but, it's a lot of code, and many files, which may not be necessary for publication.
I'm sure it's just something small; like, how timers register according to scope, and maybe how it's affected in .bind() ?
I'm really stuck with this, and I kinda need it working for a good impression for a job-interview; so if you know anything that could help, I would appreciate your input very much.
Thank you.
embedded content, onload attributes & the DOM
The following may help in related scenarios:
when targeting an asynchronous source, make sure the contentDocument or getSVGDocument() contains the resources you need to access. The window.onload, or the DOMContentLoaded event is relative to the current DOM, so it may help constructing your own listener->trigger for a cross-browser solution, because the contents you need may not be ready in a synchronous fashion.
the onload attribute/event is not triggered when inserting dynamic content that is not asynchronously loaded, but may fire under certain circumstances, so, again, a custom:
listen->trigger will solve that.
question specific
The question is directly related to the 2nd point above, and the answer is quite simple really:
in the "onload" attribute of said SVG, set a simple value as property of this like:
<svg onload="this.ready = true; setTinterval(...)"
in the constructor function, after the element was dynamically created, simply check if the svg-node's onload event was fired like so:
if (!svgNode.ready){ svgNode.onload(); }
If there is an error in your code, but no error is shown, make sure window.onerror is either null -or if it's a function, make sure it does NOT return true - else it may suppress errors and you'll have a hard time tracking down what's wrong.
Please feel free to either improve this answer, or comment and I'll improve it accordingly; however, better answers will be appreciated.
6 years later...
With vanilla JavaScript Web Components you can do:
<load-svg></load-svg>
<script>
customElements.define("load-svg", class extends HTMLElement {
connectedCallback() {
this.innerHTML = `<svg></svg>`;
setInterval(() => {
console.log("testing");
}, 500);
}
});
</script>
In tutorials I've learnt to use document.write. Now I understand that by many this is frowned upon. I've tried print(), but then it literally sends it to the printer.
So what are alternatives I should use, and why shouldn't I use document.write? Both w3schools and MDN use document.write.
The reason that your HTML is replaced is because of an evil JavaScript function: document.write().
It is most definitely "bad form." It only works with webpages if you use it on the page load; and if you use it during runtime, it will replace your entire document with the input. And if you're applying it as strict XHTML structure it's not even valid code.
the problem:
document.write writes to the document stream. Calling document.write on a closed (or loaded) document automatically calls document.open which will clear the document.
-- quote from the MDN
document.write() has two henchmen, document.open(), and document.close(). When the HTML document is loading, the document is "open". When the document has finished loading, the document has "closed". Using document.write() at this point will erase your entire (closed) HTML document and replace it with a new (open) document. This means your webpage has erased itself and started writing a new page - from scratch.
I believe document.write() causes the browser to have a performance decrease as well (correct me if I am wrong).
an example:
This example writes output to the HTML document after the page has loaded. Watch document.write()'s evil powers clear the entire document when you press the "exterminate" button:
I am an ordinary HTML page. I am innocent, and purely for informational purposes. Please do not <input type="button" onclick="document.write('This HTML page has been succesfully exterminated.')" value="exterminate"/>
me!
the alternatives:
.innerHTML This is a wonderful alternative, but this attribute has to be attached to the element where you want to put the text.
Example: document.getElementById('output1').innerHTML = 'Some text!';
.createTextNode() is the alternative recommended by the W3C.
Example: var para = document.createElement('p');
para.appendChild(document.createTextNode('Hello, '));
NOTE: This is known to have some performance decreases (slower than .innerHTML). I recommend using .innerHTML instead.
the example with the .innerHTML alternative:
I am an ordinary HTML page.
I am innocent, and purely for informational purposes.
Please do not
<input type="button" onclick="document.getElementById('output1').innerHTML = 'There was an error exterminating this page. Please replace <code>.innerHTML</code> with <code>document.write()</code> to complete extermination.';" value="exterminate"/>
me!
<p id="output1"></p>
Here is code that should replace document.write in-place:
document.write=function(s){
var scripts = document.getElementsByTagName('script');
var lastScript = scripts[scripts.length-1];
lastScript.insertAdjacentHTML("beforebegin", s);
}
You can combine insertAdjacentHTML method and document.currentScript property.
The insertAdjacentHTML() method of the Element interface parses the specified text as HTML or XML and inserts the resulting nodes into the DOM tree at a specified position:
'beforebegin': Before the element itself.
'afterbegin': Just inside the element, before its first child.
'beforeend': Just inside the element, after its last child.
'afterend': After the element itself.
The document.currentScript property returns the <script> element whose script is currently being processed. Best position will be beforebegin — new HTML will be inserted before <script> itself. To match document.write's native behavior, one would position the text afterend, but then the nodes from consecutive calls to the function aren't placed in the same order as you called them (like document.write does), but in reverse. The order in which your HTML appears is probably more important than where they're place relative to the <script> tag, hence the use of beforebegin.
document.currentScript.insertAdjacentHTML(
'beforebegin',
'This is a document.write alternative'
)
As a recommended alternative to document.write you could use DOM manipulation to directly query and add node elements to the DOM.
Just dropping a note here to say that, although using document.write is highly frowned upon due to performance concerns (synchronous DOM injection and evaluation), there is also no actual 1:1 alternative if you are using document.write to inject script tags on demand.
There are a lot of great ways to avoid having to do this (e.g. script loaders like RequireJS that manage your dependency chains) but they are more invasive and so are best used throughout the site/application.
I fail to see the problem with document.write. If you are using it before the onload event fires, as you presumably are, to build elements from structured data for instance, it is the appropriate tool to use. There is no performance advantage to using insertAdjacentHTML or explicitly adding nodes to the DOM after it has been built. I just tested it three different ways with an old script I once used to schedule incoming modem calls for a 24/7 service on a bank of 4 modems.
By the time it is finished this script creates over 3000 DOM nodes, mostly table cells. On a 7 year old PC running Firefox on Vista, this little exercise takes less than 2 seconds using document.write from a local 12kb source file and three 1px GIFs which are re-used about 2000 times. The page just pops into existence fully formed, ready to handle events.
Using insertAdjacentHTML is not a direct substitute as the browser closes tags which the script requires remain open, and takes twice as long to ultimately create a mangled page. Writing all the pieces to a string and then passing it to insertAdjacentHTML takes even longer, but at least you get the page as designed. Other options (like manually re-building the DOM one node at a time) are so ridiculous that I'm not even going there.
Sometimes document.write is the thing to use. The fact that it is one of the oldest methods in JavaScript is not a point against it, but a point in its favor - it is highly optimized code which does exactly what it was intended to do and has been doing since its inception.
It's nice to know that there are alternative post-load methods available, but it must be understood that these are intended for a different purpose entirely; namely modifying the DOM after it has been created and memory allocated to it. It is inherently more resource-intensive to use these methods if your script is intended to write the HTML from which the browser creates the DOM in the first place.
Just write it and let the browser and interpreter do the work. That's what they are there for.
PS: I just tested using an onload param in the body tag and even at this point the document is still open and document.write() functions as intended. Also, there is no perceivable performance difference between the various methods in the latest version of Firefox. Of course there is a ton of caching probably going on somewhere in the hardware/software stack, but that's the point really - let the machine do the work. It may make a difference on a cheap smartphone though. Cheers!
The question depends on what you are actually trying to do.
Usually, instead of doing document.write you can use someElement.innerHTML or better, document.createElement with an someElement.appendChild.
You can also consider using a library like jQuery and using the modification functions in there: http://api.jquery.com/category/manipulation/
This is probably the most correct, direct replacement: insertAdjacentHTML.
Try to use getElementById() or getElementsByName() to access a specific element and then to use innerHTML property:
<html>
<body>
<div id="myDiv1"></div>
<div id="myDiv2"></div>
</body>
<script type="text/javascript">
var myDiv1 = document.getElementById("myDiv1");
var myDiv2 = document.getElementById("myDiv2");
myDiv1.innerHTML = "<b>Content of 1st DIV</b>";
myDiv2.innerHTML = "<i>Content of second DIV element</i>";
</script>
</html>
Use
var documentwrite =(value, method="", display="")=>{
switch(display) {
case "block":
var x = document.createElement("p");
break;
case "inline":
var x = document.createElement("span");
break;
default:
var x = document.createElement("p");
}
var t = document.createTextNode(value);
x.appendChild(t);
if(method==""){
document.body.appendChild(x);
}
else{
document.querySelector(method).appendChild(x);
}
}
and call the function based on your requirement as below
documentwrite("My sample text"); //print value inside body
documentwrite("My sample text inside id", "#demoid", "block"); // print value inside id and display block
documentwrite("My sample text inside class", ".democlass","inline"); // print value inside class and and display inline
I'm not sure if this will work exactly, but I thought of
var docwrite = function(doc) {
document.write(doc);
};
This solved the problem with the error messages for me.
For example, lets say you have something like this:
<div data-object="{'str': '<h1>This is a nice headline</h1>'}"></div>
Is this allowed in HTML5 and will it render properly in all browsers?
Edit:
With properly I mean that the browser will ignore and NOT render the H1 in any way ;)
Yes, it's allowed as long as it's quoted correctly.
Will it render? The H1 element? No - because it's not an element, it's just a bit of text inside an attribute of the div element.
Yes, browsers won't render any HTML tags inside attributes. This is pretty much common when you want to move the element later so it would show up. The only problem is that this is not a way to go as this does not create an element in DOM, thus, it will be much slower.
Try to find a way or ask for an alternative/better way to reuse the element which is hidden when the page is loaded.
Yes it's allowed and possible, but to make it work you have to make it valid JSON by using double quotes:
<div data-object='{"str": "<h1>This is a nice headline</h1>"}'></div>
Now to parse it just have: (jQuery will parse it to JSON all by itself)
var element = $("div").eq(0);
var rawData = element.data("object");
var rawHTML = rawData["str"];
$(rawHTML).appendTo("body");
Live test case.
First off, thanks for taking the time to read this question. What a great community Stack Overflow has :)
I need to change the title tag of a page based on the text contained in the h1 element on that page.
I've been searching around, and I have found the "document.title" Javascript function. I've been playing around with it, trying to pull the text from my h1 element that has the class of "Category-H1".
<script type="text/javascript">
document.title = document.getElementsByClassName("Category-H1");
</script>
However, it is just setting the page title to "[object HTMLCollection]", which as I understand is a null value. Is JS the best was to do this? I know my code is jacked, any tips?
Thanks in advance! - Alex
Edit
I have been informed that line of code returns a collection object and not a string. It was pointed to a code example of:
setTimeout(function () { document.title = "iFinity User Profile - " + document.getElementById("test").outerText; }, 1000);
However, this code produces a page title of "iFinity User Profile - undefined". I have the h1 element on that page set to the id of "test".
You're almost there.
[object HTMLCollection] is not a null value--it is the string representation of a collection of html elements. You want to choose the first one and then get the inner html from it.
document.getElementsByClassName("Category-H1")[0].innerHTML
Also, make sure you do this after the document has loaded. You can either do this by adding the script at the end of your document, or have it run on the onload event of the body.
This should work:
document.title = document.getElementsByClassName("Category-H1")[0].innerHTML;
The getElementsByClassName() function returns a collections of elements ( [object HTMLCollection], so you need to get an element out of it, I'm assuming the first one.
A better solution may be the following:
<script type="text/javascript">
document.title = document.getElementsByTagName("H1")[0].innerHTML
</script>
This would save from setting a h1 class.
This is very close, but I found that - working with Firefox anyway, when you use the getElementsByTagName("H1") it gives you an array as you have recognized. However, it works better using:
<script type="text/javascript">
document.title = document.getElementsByTagName("H1").item(0).innerHTML;
</script>
Note the addition of the .item(0).innerHTML after getting the element rather than the [0].innerHTML.
I don’t know if you have any experience in it or not, but another alternative that seems to be very popular these days is the use of jQuery. As in the earlier discussions, the code below assumes that you are interested in grabbing the first instance of the “H1” tag or the “Category-H1” class. This is an important point because unless you target an “ID” attribute, you will get a collection of items.
This code also assumes that you have already implemented the inclusion of the jQuery library either directly from your website or by referencing a CDN.
<script type="text/javascript">
$(document).ready(function () {
document.title = $("H1")[0].innerText;
});
</script>
The $(document).ready will call it’s enclosed function only after the Document Object Model (DOM) has finished loading, and before the browser’s rendering engine displays the page.
The content inside the function will grab the inner text of the first instance of the “H1” tag and assign that text value to the document’s title tag in the head section.
I hope this adds another layer of help.