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I'm trying to figure out how to do a switch statement where I need to find a class name of the object, then do something depending on the class name (in the switch statement).
In this example, I need the switch statement to do whatever I need when the class contains a specific word, such as "person".
html
<div class="person temp something"></div>
javascript
$(document).on('mousedown', function(e) {
var clicked = $(e.target).attr('class');
console.log(clicked);
switch (clicked) {
case "person":
//do something
break;
default:
//do something
}
});
It's not guaranteed that the switch statement name, such as "person" will be in the first spot.
I know I can search through an array for a specific word, but I don't know how to add that to this sort of thing.
As I said in my comment, a switch statement doesn't appear the appropriate approach in this situation.
Since you are using jQuery, just use .hasClass:
if ($(e.target).hasClass('person')) {
// do something
}
If you want to do something more complicated for multiple classes, you can create a class -> function mapping and simply iterate over the class list:
var classActions = {
person: function(element) { /* do something */ },
temp: function(element) { /* do something */},
// ...
};
var classes = e.target.className.split(/\s+/);
$.each(classes, function(index, cls) {
classActions[cls](e.target);
});
You'll want to use a combination of .split() and .indexOf(). Your code would be something like this:
var clicked = $(e.target).attr('class');
var classes = clicked.split(' ');
if(classess.indexOf('person') > 0) {
//do work
} else if (classes.indexOf('foo') > 0) {
//do work
} else if (classes.indexOf('bar') > 0) {
//do work
}
MDN documentation on .split()
MDN documentation on .indexOf()
Note that there are plenty of methods that allow you to do this. For example you can use string.search(substring) to check if a string contains your substring. If there is a substring it returns the index it was found (some number from 0 to n), otherwise if it's not found it returns -1. So if the search is larger or equal to 0, the substring exist.
if(clicked.search("person") >= 0)
// "person" is in clicked
After long hours of work I figured out how to get my ajax value. It looks like this:
37,58,82,
I managed out how to remove last comma and make array like this:
Object { 0="37", 1="58", 2="82"}
But I need it to be like this (according to firebug):
[Object { trackID="track-id-37"}, Object { trackID="track-id-58"}, Object { trackID="track-id-58"},]
How can I make it to look like?
Here you go. If you have your array, you can call $.map on it.
$.map(["37", "58", "82"], function(elem) { return { trackID: "track-id-" + elem }; });
Or let's say your string is called your_string...we can act directly on it (I've added whitespace to make it clear what's going on)--
your_string = '37,58,82,';
$.map(your_string.split(','), function(elem)
{
if (elem != '')
{
return { trackID: "track-id-" + elem };
}
});
The if (elem != '') statement is to protect against any empty array values after the split(','). $.map tolerates return values of undefined.
Also consider using $.trim on elem in order to build in tolerance for spaces and so on, e.g.
$.map(your_string.split(','), function(elem)
{
var id = $.trim(elem);
if (id != '')
{
return { trackID: "track-id-" + id };
}
});
I am currently learning jQuery. I know that jQuery is a custom library for JavaScript.
I am doing some learning examples in a book that is only using JavaScript, and to further my learning experience, I am trying to make use of jQuery for anything that might be more efficient.
So, I have this code:
function addLetter(foo) {
$(foo).unbind('click');
var tileLetter = $(foo).attr('class').split(' ');
var letter = tileLetter[2].charAt(1);
if (document.getElementById('currentWord').childNodes.length > 0) {
$('#currentWord p').append(letter);
} else {
var p = document.createElement('p');
var txt = document.createTextNode(letter);
p.appendChild(txt);
$('#currentWord').append(p);
}
}
Question #1:
If I change document.getElementById('currentWord').childNodes.length to $('#currentWord').childNodes.length it doesn't work. I thought the jQuery selector was the same thing as the JS document.getElementById as that it brought me back the DOM element. If that was the case, it'd make sense to be able to use the .childNodes.length functions on it; but it doesn't work. I guess it's not the same thing?
Question #2:
The code is textbook code. I have added all the jQuery that there is in it. My jQuery knowlede is limited, is there a more efficient way to execute the function?
The function's purpose:
This function is supposed to create a p element and fill it with a Text Node if it's the first time it's run. If the p element has already been created, it simply appends characters into it.
This is a word generating game, so you click on a letter and it gets added to a 'currentWord' div. The tile's letter is embedded in the 3rd css class, hence the attr splitting.
Thanks!
document.getElementById('currentWord')
returns a DOM object whereas $('#currentWord') returns a DOM object wrapped inside a jQuery object.
To get the plain DOM object you can do
$('#currentWord').get(0)
So
$('#currentWord').get(0).childNodes.length
should work.
Question #1:
jQuery returns a jQuery object. To return it to a regular javascript object use $(object)[0] and you can then treat it as a plain javascript (or DOM) object.
Question #2:
The efficiency looks good to me. Although you might want to use spans instead of p elements.
I guess one thing you could do (even though yours looks to run very fast) is cache the dom element:
function addLetter(foo) {
$(foo).unbind('click');
var tileLetter = $(foo).attr('class').split(' ');
var letter = tileLetter[2].charAt(1);
var currentWord = document.getElementById('currentWord');
if (currentWord.childNodes.length > 0) {
$(currentWord).find('p').append(letter);
} else {
var p = document.createElement('p');
p.innerHTML = letter;
currentWord.appendChild(p);
}
}
Calls to the jQuery() function ($()) return a jQuery object containing the matching elements, not the elements themselves.
Calling $('#some-id') will, then, return a jQuery object that contains the element that would be selected by doing document.getElementById('some-id'). In order to access that element directly, you can get it out of that jQuery object, using either the .get() function or an array index syntax: $('#some-id')[0] (it's 0-indexed).
I think you can replace all of this with a call to the text function.
function addLetter(foo) {
$(foo).unbind('click');
var tileLetter = $(foo).attr('class').split(' ');
var letter = tileLetter[2].charAt(1);
var currentWordP = $('#currentWord p');
if (currentWordP.size() > 0) {
currentWordP.text(currentWordP.text() + letter);
} else {
$('#currentWord').append("<p>" + letter + "</p>");
}
}
1: Use $.get(0) or $[0] to get the DOM element. e.x. $('#currentWord')[0].childNodes.length.
2: Try this:
function addLetter(foo) {
$(foo).unbind('click');
var tileLetter = $(foo).attr('class').split(' ');
var letter = tileLetter[2].charAt(1);
if ($('#currentWord p').length > 0) {
$('#currentWord p').append(letter);
} else {
$('#currentWord').append(
$('<p />', { text: letter })
);
}
}
Question #1:
document.getElementById returns DOM object. more
childNodes.length is property of Node object which is returned by document.getElementById.
jQuery selector returns jQuery object more. You can get DOM object from jQuery object using .get
$('#IDselector').get(0) = document.getElementById('IDselector')
Question #2:
function addLetter(foo) {
$(foo).unbind('click');
var tileLetter = $(foo).attr('class').split(' ');
var letter = tileLetter[2].charAt(1);
if ($('currentWord p').length > 0) {
$('#currentWord p').append(letter);
} else {
var p = $('<p />').text(letter);
$('#currentWord').append(p);
}
}
I have an XHTML page where each HTML element has a unique custom attribute, like this:
<div class="logo" tokenid="14"></div>
I need a way to find this element by ID, similar to document.getElementById(), but instead of using a general ID, I want to search for the element using my custom "tokenid" attribute. Something like this:
document.getElementByTokenId('14');
Is that possible? If yes - any hint would be greatly appreciated.
Thanks.
It is not good to use custom attributes in the HTML. If any, you should use HTML5's data attributes.
Nevertheless you can write your own function that traverses the tree, but that will be quite slow compared to getElementById because you cannot make use of any index:
function getElementByAttribute(attr, value, root) {
root = root || document.body;
if(root.hasAttribute(attr) && root.getAttribute(attr) == value) {
return root;
}
var children = root.children,
element;
for(var i = children.length; i--; ) {
element = getElementByAttribute(attr, value, children[i]);
if(element) {
return element;
}
}
return null;
}
In the worst case, this will traverse the whole tree. Think about how to change your concept so that you can make use browser functions as much as possible.
In newer browsers you use of the querySelector method, where it would just be:
var element = document.querySelector('[tokenid="14"]');
This will be much faster too.
Update: Please note #Andy E's comment below. It might be that you run into problems with IE (as always ;)). If you do a lot of element retrieval of this kind, you really should consider using a JavaScript library such as jQuery, as the others mentioned. It hides all these browser differences.
<div data-automation="something">
</div>
document.querySelector("div[data-automation]")
=> finds the div
document.querySelector("div[data-automation='something']")
=> finds the div with a value
If you're using jQuery, you can use some of their selector magic to do something like this:
$('div[tokenid=14]')
as your selector.
You can accomplish this with JQuery:
$('[tokenid=14]')
Here's a fiddle for an example.
If you're willing to use JQuery, then:
var myElement = $('div[tokenid="14"]').get();
Doing this with vanilla JavaScript will do the trick:
const something = document.querySelectorAll('[data-something]')
Use this more stable Function:
function getElementsByAttribute(attr, value) {
var match = [];
/* Get the droids we are looking for*/
var elements = document.getElementsByTagName("*");
/* Loop through all elements */
for (var ii = 0, ln = elements.length; ii < ln; ii++) {
if (elements[ii].nodeType === 1){
if (elements[ii].name != null){
/* If a value was passed, make sure it matches the elements */
if (value) {
if (elements[ii].getAttribute(attr) === value)
match.push(elements[ii]);
} else {
/* Else, simply push it */
match.push(elements[ii]);
}
}
}
}
return match;
};
Is there a way in jQuery to loop through or assign to an array all of the classes that are assigned to an element?
ex.
<div class="Lorem ipsum dolor_spec sit amet">Hello World!</div>
I will be looking for a "special" class as in "dolor_spec" above. I know that I could use hasClass() but the actual class name may not necessarily be known at the time.
You can use document.getElementById('divId').className.split(/\s+/); to get you an array of class names.
Then you can iterate and find the one you want.
var classList = document.getElementById('divId').className.split(/\s+/);
for (var i = 0; i < classList.length; i++) {
if (classList[i] === 'someClass') {
//do something
}
}
jQuery does not really help you here...
var classList = $('#divId').attr('class').split(/\s+/);
$.each(classList, function(index, item) {
if (item === 'someClass') {
//do something
}
});
Why has no one simply listed.
$(element).attr("class").split(/\s+/);
EDIT: Split on /\s+/ instead of ' ' to fix #MarkAmery's objection. (Thanks #YashaOlatoto.)
On supporting browsers, you can use DOM elements' classList property.
$(element)[0].classList
It is an array-like object listing all of the classes the element has.
If you need to support old browser versions that don't support the classList property, the linked MDN page also includes a shim for it - although even the shim won't work on Internet Explorer versions below IE 8.
Here is a jQuery plugin which will return an array of all the classes the matched element(s) have
;!(function ($) {
$.fn.classes = function (callback) {
var classes = [];
$.each(this, function (i, v) {
var splitClassName = v.className.split(/\s+/);
for (var j = 0; j < splitClassName.length; j++) {
var className = splitClassName[j];
if (-1 === classes.indexOf(className)) {
classes.push(className);
}
}
});
if ('function' === typeof callback) {
for (var i in classes) {
callback(classes[i]);
}
}
return classes;
};
})(jQuery);
Use it like
$('div').classes();
In your case returns
["Lorem", "ipsum", "dolor_spec", "sit", "amet"]
You can also pass a function to the method to be called on each class
$('div').classes(
function(c) {
// do something with each class
}
);
Here is a jsFiddle I set up to demonstrate and test http://jsfiddle.net/GD8Qn/8/
Minified Javascript
;!function(e){e.fn.classes=function(t){var n=[];e.each(this,function(e,t){var r=t.className.split(/\s+/);for(var i in r){var s=r[i];if(-1===n.indexOf(s)){n.push(s)}}});if("function"===typeof t){for(var r in n){t(n[r])}}return n}}(jQuery);
You should try this one:
$("selector").prop("classList")
It returns a list of all current classes of the element.
var classList = $(element).attr('class').split(/\s+/);
$(classList).each(function(index){
//do something
});
$('div').attr('class').split(' ').each(function(cls){ console.log(cls);})
Update:
As #Ryan Leonard pointed out correctly, my answer doesn't really fix the point I made my self... You need to both trim and remove double spaces with (for example) string.replace(/ +/g, " ").. Or you could split the el.className and then remove empty values with (for example) arr.filter(Boolean).
const classes = element.className.split(' ').filter(Boolean);
or more modern
const classes = element.classList;
Old:
With all the given answers, you should never forget to user .trim() (or $.trim())
Because classes gets added and removed, it can happen that there are multiple spaces between class string.. e.g. 'class1 class2 class3'..
This would turn into ['class1', 'class2','','','', 'class3']..
When you use trim, all multiple spaces get removed..
Might this can help you too. I have used this function to get classes of childern element..
function getClickClicked(){
var clickedElement=null;
var classes = null;<--- this is array
ELEMENT.on("click",function(e){//<-- where element can div,p span, or any id also a class
clickedElement = $(e.target);
classes = clickedElement.attr("class").split(" ");
for(var i = 0; i<classes.length;i++){
console.log(classes[i]);
}
e.preventDefault();
});
}
In your case you want doler_ipsum class u can do like this now calsses[2];.
Thanks for this - I was having a similar issue, as I'm trying to programatically relate objects will hierarchical class names, even though those names might not necessarily be known to my script.
In my script, I want an <a> tag to turn help text on/off by giving the <a> tag [some_class] plus the class of toggle, and then giving it's help text the class of [some_class]_toggle. This code is successfully finding the related elements using jQuery:
$("a.toggle").toggle(function(){toggleHelp($(this), false);}, function(){toggleHelp($(this), true);});
function toggleHelp(obj, mode){
var classList = obj.attr('class').split(/\s+/);
$.each( classList, function(index, item){
if (item.indexOf("_toggle") > 0) {
var targetClass = "." + item.replace("_toggle", "");
if(mode===false){$(targetClass).removeClass("off");}
else{$(targetClass).addClass("off");}
}
});
}
Try This. This will get you the names of all the classes from all the elements of document.
$(document).ready(function() {
var currentHtml="";
$('*').each(function() {
if ($(this).hasClass('') === false) {
var class_name = $(this).attr('class');
if (class_name.match(/\s/g)){
var newClasses= class_name.split(' ');
for (var i = 0; i <= newClasses.length - 1; i++) {
if (currentHtml.indexOf(newClasses[i]) <0) {
currentHtml += "."+newClasses[i]+"<br>{<br><br>}<br>"
}
}
}
else
{
if (currentHtml.indexOf(class_name) <0) {
currentHtml += "."+class_name+"<br>{<br><br>}<br>"
}
}
}
else
{
console.log("none");
}
});
$("#Test").html(currentHtml);
});
Here is the working example: https://jsfiddle.net/raju_sumit/2xu1ujoy/3/
For getting the list of classes applied to element we can use
$('#elementID').prop('classList')
For adding or removing any classes we can follow as below.
$('#elementID').prop('classList').add('yourClassName')
$('#elementID').prop('classList').remove('yourClassName')
And for simply checking if the class is present or not we can use hasClass
I had a similar issue, for an element of type image. I needed to check whether the element was of a certain class. First I tried with:
$('<img>').hasClass("nameOfMyClass");
but I got a nice "this function is not available for this element".
Then I inspected my element on the DOM explorer and I saw a very nice attribute that I could use: className. It contained the names of all the classes of my element separated by blank spaces.
$('img').className // it contains "class1 class2 class3"
Once you get this, just split the string as usual.
In my case this worked:
var listOfClassesOfMyElement= $('img').className.split(" ");
I am assuming this would work with other kinds of elements (besides img).
Hope it helps.
javascript provides a classList attribute for a node element in dom. Simply using
element.classList
will return a object of form
DOMTokenList {0: "class1", 1: "class2", 2: "class3", length: 3, item: function, contains: function, add: function, remove: function…}
The object has functions like contains, add, remove which you can use
A bit late, but using the extend() function lets you call "hasClass()" on any element, e.g.:
var hasClass = $('#divId').hasClass('someClass');
(function($) {
$.extend({
hasClass: new function(className) {
var classAttr = $J(this).attr('class');
if (classAttr != null && classAttr != undefined) {
var classList = classAttr.split(/\s+/);
for(var ix = 0, len = classList.length;ix < len;ix++) {
if (className === classList[ix]) {
return true;
}
}
}
return false;
}
}); })(jQuery);
The question is what Jquery is designed to do.
$('.dolor_spec').each(function(){ //do stuff
And why has no one given .find() as an answer?
$('div').find('.dolor_spec').each(function(){
..
});
There is also classList for non-IE browsers:
if element.classList.contains("dolor_spec") { //do stuff