Develop Reference

Check if document contains a class similar to the specified string in Javascript

I am trying to find all elements that contain 'ad'.
Such as:
<iframe class="container" /> <!-- False -->
<a class="adp" /> <!-- True -->
<a class="adleft" /> <!-- True -->
<a class="some-other-class" /> <!-- False -->
Could I use a forEach?
I appreciate any help from everyone.

You can simply achieve this with the combination of querySelectorAll and attribute selector by using the [attr*=value] syntax.
The above attribute selector syntax will work like:
Represents elements with an attribute name of attr whose value contains at least one occurrence of value within the string.
The outcome combination of above solution will be something like this:
document.querySelectorAll("[class*='ad']");
Which give you all the elements whose contain ad within their class names. Then you can simply use a simple loop or array helper like Array#forEach to use the outcome. Note that the previous outcome will produce an HTMLCollection which needs to convert into an array before using array helpers, otherwise you can use the traditional for loop over it.
Here how the final code should look like:
const ads = document.querySelectorAll("[class*='ad']");
Array.from(ads).forEach(el => {
console.log(el);
})
<iframe class="container"></iframe>
<a class="adp"></a>
<a class="adleft"></a>
<a class="some-other-class"></a>
NOTE: You always need to properly open and close HTML tags especially iframe. Since it is not assumed as a self-closing tag it will lead to invalid HTML markup.

You can use an attribute selector to get every elements containing ad. You can read more about it here : doc
document.querySelectorAll('*[class*="ad"]');

Javascript / Greasemonkey / Userscript.js identify element and remove one of many classes

I've spent far too many hours trying to figure this out and as JavaScript is not my primary language and not yet a jQuery guru I've determined I need to ask for help.
In a case where a generated page has a structure where it has a DIV for some odd reason no ID, multiple non-standard data tag attribute tags, but at least standard style CLASS assignment....however...it has been assigned MULTIPLE classes.
Now, just one of those style classes is such that it has a code event associated that I want to neuter and leave all other classes still assigned. What I've tried there (this list is far from complete I have tried many things):
document.getElementsByClassName('Goodclass01')[0].remove('BADCLASS');
document.querySelectorAll('[data-tag-one="["value",
"value"]"]').remove('BADCLASS');
Various jnode calls that all fail due to claims of being unknown
A couple variations of something referred to as the "location hack" none of
which I could get to work but may have very well have been user error.
Safewindow attempt to just replace BADCLASS javascript function all together
but not ideal explained below.
Here is an example of the kind of structure of the target:
<div id="main">
<div class="main_content" data-tag-id="12345">Some stuff sits above</div>
<a href="SOME LINK" class="Goodclass01 Goodclass02 Goodclass03 BADCLASS"
data-tag-one="["value", "value"]">
</div>
In this example there is a javascript function that fires upon clicking the href link above due to the function being associated with BADCLASS style assignment. So, from lots of searching it seemed like I should be able to grab that DIV by any of the initially assigned classes (since there is unfortunately not a class ID which would make it very easy) but then reassign the list of classes back minus the BADCLASS at page load time. So, by the time the user clicks the link, the BADCLASS has been removed to look like this:
<div id="main">
<div class="main_content" data-tag-id="12345">Some stuff sits above</div>
<a href="SOME LINK" class="Goodclass01 Goodclass02 Goodclass03"
data-tag-one="["value", "value"]">
</div>
I also read that simply using unsafewindow to replace the BADCLASS javascript function could be possible, so I am open to hearing one of you gurus help with how easy (or hard) that would be. In a case where BADCLASS could be shared function code perhaps called by another element on the page still having that initial class that perhaps we desire to continue to function which is why if it is only a single element that needs to be altered, I would rather just change this one href div.
Hope the explanation makes sense and what is probably a laughable simple example above for the Javascript gurus so forgive me but your help is greatly appreciated and will save more hair pulling! :)
EDIT: This must work above all in Chrome browser!

Remove the class from all elements
If you want to remove the class from all elements that have the class, simply select all of the elements with that class and remove the class from their class lists.
[...document.querySelectorAll('.BADCLASS')]
.forEach(e => e.classList.remove('BADCLASS'));
const elements = [...document.querySelectorAll('.BADCLASS')];
elements.forEach(e => e.classList.remove('BADCLASS'));
console.log(elements);
<div id="main">
<div class="main_content" data-tag-id="12345">Some stuff sits above</div>
<a href="SOME LINK" class="Goodclass01 Goodclass02 Goodclass03 BADCLASS"
data-tag-one='["value", "value"]'>link</a>
</div>
Using jQuery:
$('.BADCLASS').removeClass('BADCLASS');
const elements = $('.BADCLASS');
elements.removeClass('BADCLASS');
console.log(elements);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="main">
<div class="main_content" data-tag-id="12345">Some stuff sits above</div>
<a href="SOME LINK" class="Goodclass01 Goodclass02 Goodclass03 BADCLASS"
data-tag-one='["value", "value"]'>link</a>
</div>
Remove the class from a subset of elements
If you only want to remove the class from a subset elements, select those elements then from the class from their class lists.
[...document.querySelectorAll('.Goodclass01, .Goodclass02, .Goodclass03')]
.forEach(e => e.classList.remove('BADCLASS'));
const elements = [...document.querySelectorAll('.Goodclass01, .Goodclass02, .Goodclass03')];
elements.forEach(e => e.classList.remove('BADCLASS'));
console.log(elements);
<div id="main">
<div class="main_content" data-tag-id="12345">Some stuff sits above</div>
<a href="SOME LINK" class="Goodclass01 Goodclass02 Goodclass03 BADCLASS"
data-tag-one='["value", "value"]'>link</a>
link
</div>
Using jQuery:
$('.Goodclass01, .Goodclass02, .Goodclass03').removeClass('BADCLASS');
const elements = $('.Goodclass01, .Goodclass02, .Goodclass03');
elements.removeClass('BADCLASS');
console.log(elements);
<div id="main">
<div class="main_content" data-tag-id="12345">Some stuff sits above</div>
<a href="SOME LINK" class="Goodclass01 Goodclass02 Goodclass03 BADCLASS"
data-tag-one='["value", "value"]'>link</a>
link
</div>
Run at document idle
The default for the run-at directive is document-idle, but if for some reason that has been changed, either it needs to be document-idle, or you need to otherwise delay execution of the script until the document has loaded.
You could use the run-at directive in the userscript header like so:
// #run-at document-idle
Or attach a load event listener to the window
window.addEventListener('load', function() { /* do stuff */ }, false);
Include jQuery
If you're using one of the jQuery solutions, you will have to include jQuery using the require userscript header directive like so:
// #require https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js

Got it with the help of both of the clear, awesome correct answers below that literally came in within seconds of each other and only a few min after my post, so thanks to both #Tiny and #Damian below!
I'm upvoting both as they both listed the same correct jQuery answers, and Tiny also provided the pure JS.
I am posting the full answer below because without the other steps, with Tamper/Greasemonkey neither will produce the desired results.
First, Tamper/Greasemonkey do not load jQuery by default, so it is just easy as add #require http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.mi‌​n.js to your current script and also put this.$ = this.jQuery = jQuery.noConflict(true); to avoid any versioning conflicts.
Also, in this case unfortunately I HAD to change my TamperMonkey header to:
// #run-at document-idle
along with the above mentioned:
// #require http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js
and begin the script with:
this.$ = this.jQuery = jQuery.noConflict(true);
and finally the primary accepted/best answer in this case of:
$('.Goodclass01').removeClass('BADCLASS');
NOTE: The above #run-at line is required, and since so many (all) of my current Tamper/Greasemonkey scripts are actually set by default to run at START, this is of importance as it means functions like this must be separated to their own scripts to run instead AFTER the page loads (idle). Once this is added, even the above pure JS answer from Tiny did in fact produce the desired result.
As the simplest one-line answer that I was hoping was possible in Javascript, as it is so many other languages in a single line of code. I've used it in the past, but was not aware of this particular removeClass method.

Your question mentions jQuery. Did you want a solution in jQuery?
If so, it's as easy as:
$(".Goodclass01").removeClass("badclass");
Explanation:
jQuery can be referenced as jQuery() or $(). The parameters you can pass are: 1, a Selector statement (like CSS), and 2, context (optional; default is document).
By stating $(".Goodclass01") you are stating, "Give me a jQuery object with all elements that have the class Goodclass01." Then, by using the removeClass() function, you can either pass it no parameters and it would remove all classes, or you can pass it specific classes to remove. In this case, we call .removeClass("badclass") in order to remove the undesired class.
Now, if you need to select only specific elements, such as links that have Goodclass01, you can do:
$("a.GoodClass01").removeClass("badclass");
Or, if you want to select anything that has Goodclass01, but NOT Goodclass02, you can do:
$(".Goodclass01:not(.Goodclass02)").removeClass("badclass");
jQuery is not as intimidating as it looks. Give it a shot!
Edit: I also noticed you were trying to capture a link with maybe a specific property. You can use the [property] syntax to select elements that have a specific property. Most typically, people use $("a[href^=https]") or something to that effect to select all a tags with the property href that begins with ^= the string https.
You could, in your case, use the following...
$("a[data-tag-one]")
... to select all links that have the property data-tag-one.
Note: One thing to keep in mind is that, a jQuery object is different than a pure DOM element. If you have a collection of multiple elements and want to use a pure JavaScript function on one element in particular, you would have to reference it with either [0] or .get(0). Once you do that, you will no longer be able to use jQuery methods until you convert it back to a jQuery object.
But, since jQuery has a whole slew of methods to use to make DOM manipulation easier, you can probably accomplish what you need to using those methods.
Edit: I've included a snippet below so you can see some of the jQuery selectors in action.
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<style>
div#main * { background-color: #66ff66; }
div#main .BADCLASS, div#main .BADCLASS * { background-color: #ff8888 !important; }
</style>
<div id="main">
<div class="main_content" data-tag-id="12345">Some stuff sits above</div>
<a href="SOME LINK" class="Goodclass01 Goodclass02 Goodclass03 BADCLASS"
data-tag-one='["value", "value"]'>All classes and data-tag-one</a><br />
<a href="SOME LINK" class="Goodclass01 BADCLASS" data-tag-one='["value", "value"]'>Goodclass01 and data-tag-one</a><br />
All classes, no data-tag-one<br />
<a href="SOME LINK" class="BADCLASS" data-tag-one='["value", "value"]'>Just BADCLASS and data-tag-one</a><br />
<br />
<table class="Goodclass01 BADCLASS"><tr><td>Here is a table</td></tr><tr><td>with Goodclass01 and BADCLASS</td></tr></table>
</div>
<hr>
<div id="buttons">
$(".Goodclass01").removeClass("BADCLASS");<br />
$("a.Goodclass01").removeClass("BADCLASS");<br />
$(".Goodclass01:not(.Goodclass02)").removeClass("BADCLASS");<br />
$("a[data-tag-one]").removeClass("BADCLASS");<br />
Reset the HTML<br />
</div>
<script>
$("#button1").click(function(){
$(".Goodclass01").removeClass("BADCLASS");
});
$("#button2").click(function(){
$("a.Goodclass01").removeClass("BADCLASS");
});
$("#button3").click(function(){
$(".Goodclass01:not(.Goodclass02)").removeClass("BADCLASS");
});
$("#button4").click(function(){
$("a[data-tag-one]").removeClass("BADCLASS");
});
$("#button5").click(function(){
var str = '<div class="main_content" data-tag-id="12345">Some stuff sits above</div>All classes, no data-tag-one<br /><a href="SOME LINK" class="BADCLASS" data-tag-one=\'["value", "value"]\'>Just BADCLASS and data-tag-one</a><br /><br /><table class="Goodclass01 BADCLASS"><tr><td>Here is a table</td></tr><tr><td>with Goodclass01 and BADCLASS</td></tr></table>';
$("div#main").html(str);
});
</script>

passing variables on jquery

just having some issues with this jQuery thing.
What i'm trying to do is:
i have some audio control buttons that look like this:
<p>Play audio</p>
but there are too many on the page so i'm trying to optimise the code and make a little function that checks for the div id on the button and adds tells the player what track to play.
so i've done this:
<div id="audioControlButtons-1">
<div class="speaker"> </div>
<div class="play"> </div>
<div class="pause"> </div>
</div>
<script>
$(document).ready(function() {
$("[id^=audioControlButtons-] div.play").click(function() {
var id = new Number;
id = $(this).parent().attr('id').replace(/audioControlButtons-/, '');
//alert(id);
player1.loadAudio(id);
return false;
});
});
</script>
my problem is:
the id is not passing to the the player1.loadAudio(id)
if i hardcode player1.loadAudio(1)
it works! but the moment i try to pass the variable to the function it doesn't work...
however if you uncomment the alert(id) thing you will see the id is getting generated...
can someone help?
cheers,
dan

I think I see your problem. The variable id is a string. Try;
player1.loadAudio(parseInt(id));
Yah and the initialise line isn't necessary. Just use;
var id = $(this).parent().attr('id').replace(/audioControlButtons-/, '');

I'm actually kind of confused with your example because you originally have this:
<p>Play audio</p>
but then you don't reference it again. Do you mean that this html:
<div id="audioControlButtons-1">
<div class="speaker"> </div>
<div class="play"> </div>
<div class="pause"> </div>
</div>
Is what you are actually creating? If so, then you can rewrite it like this:
<div class="audio-player">
<div class="speaker"> </div>
<div class="play" data-track="1"> </div>
<div class="pause"> </div>
</div>
Then in your script block:
<script>
$(document).ready(function() {
$(".audio-player > .play").click(function() {
var track = $(this).data('track');
player1.loadAudio(+track);
return false;
});
});
</script>
So a few things are going on here.
I just gave your containing div a class (.audio-player) so that it's much more generic and faster to parse. You don't want to do stuff like [id^=audioControlButtons-] because it is much slower for the javascript to traverse and parse the DOM like that. And if you are going to have multiples of the same element on the page, a class is much more suited for that over IDs.
I added the track number you want to the play button as a data attribute (data-track). Using a data attribute allows you to store arbitrary data on DOM elements you're interested on (ie. .play button here). Then this way, you don't need to this weird DOM traversal with a replace method just to get the track number. This saves on reducing unnecessary JS processing and DOM traversing.
With this in mind now, I use jQuery's .data() method on the current DOM element with "track" as the argument. This will then get the data-track attribute value.
With the new track number, I pass that along into your player1.loadAudio method with a + sign in front. This is a little javascript trick that allows you to convert your value into an actual number if that is what the method requires.
There are at least a couple of other optimizations you can do here - event delegation, not doing everything inside the ready event - but that is beyond the scope of this question. Hell, even my implementation could be a little bit optimized, but again, that would require a little bit more in depth explanation.

JavaScript: How should I generate a lot of HTML? [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Is there a best practice for generating html with javascript
I want to generate large parts of a website with JavaScript.
The straightforward way is to form one large string containing all the HTML:
'<div>'
+ '<span>some text</span>'
+ '<form>'
+ '<input type="text" />'
...
But this gets quite annoying when one has to write a few hundred lines in this style. And the pain when such code has to be changed later on...
Can you think of an easier way?

Create snippets as templates, put them into an invisible <div>:
<div style="display: none">
<div id="template1">
<h2 class="header_identifyingClass">Hello from template</h2>
</div>
<div id="template2">
<span class="content">Blah blah</span>
</div>
</div>
Then find it,
document.getElementById("template1");
fill it's internal values, e.g. find inside elements by XPath or jQuery and fill them e.g. using element.innerHTML = "Hello from new value", and move or copy it to the visible part of DOM.
Create multiple templates and copy it multiple times to generate many.
Don't forget to change the ID for copies to keep it working.
PS: I think I used this approach in the code of JUnitDiff project. But it's buried in XSLT which serves another purpose.

By far the best way to do this is to use some kind of JavaScript templating system. The reason why this is better than hiding HTML with CSS is that if (for example) someone has CSS disabled, they'll be able to see your templates, which is obviously not ideal.
With a templating system, you can put the templates in a <script> tag, meaning that they're totally hidden from everything except JavaScript.
My favourite is the jQuery templating system, mostly because jQuery is so ubiquitous these days. You can get it from here: http://api.jquery.com/category/plugins/templates/
An example (taken from the jQuery docs):
<ul id="movieList"></ul>
<!-- the template is in this script tag -->
<script id="movieTemplate" type="text/x-jquery-tmpl">
<li><b>${Name}</b> (${ReleaseYear})</li>
</script>
<!-- this script will fill out the template with the values you assign -->
<script type="text/javascript">
var movies = [
{ Name: "The Red Violin", ReleaseYear: "1998" },
{ Name: "Eyes Wide Shut", ReleaseYear: "1999" },
{ Name: "The Inheritance", ReleaseYear: "1976" }
];
// Render the template with the movies data and insert
// the rendered HTML under the "movieList" element
$( "#movieTemplate" ).tmpl( movies )
.appendTo( "#movieList" );
</script>
It's a simple example, but you could put all of the HTML you'd like to generate in the <script>, making it much more flexible (use the same HTML snippet for various jobs, just fill out the gaps), or even use many templates to build up a larger HTML snippet.

Use a dialect of JavaScript such as CoffeeScript. It has heredocs:
'''
<div>
<span>some text</span>
<form>
<input type="text" />
'''
If you need to throw in an occasional expression, you can use interpolations:
"""
<title>#{title}</title>
"""

If it's static content that you're just adding to the page on a javascript event, you could consider simply having it in your main HTML page all along, but style with display:none;.
Then it's just a case of changing it's style to make it appear on the page. Much easier.
Even if it's dynamic, you could use this technique: have the shell HTML content there hidden in your page, and populate the dynamic bits before making it visible.
hope that helps.

best way to inject html using javascript

I'm hoping that this isn't too subjective. I feel there is a definitive answer so here goes.
I want to create this html on the fly using JS (no libraries):
Play
Mute
<div id="progressBarOuter">
<div id="bytesLoaded"></div>
<div id="progressBar"></div>
</div>
<div id="currentTime">0:00</div>
<div id="totalTime">0:00</div>
using javascript. I know I can do this using createElement etc but it seems extremely long winded to do this for each element. Can anyone suggest a way to do this with more brevity.
I do not have access to a library in this project....so no jquery etc.

Keep your markup separate from your code:
You can embed the HTML snippets that you'll be using as hidden templates inside your HTML page and clone them on demand:
<style type="text/css">
#templates { display: none }
</style>
...
<script type="text/javascript">
var node = document.getElementById("tmp_audio").cloneNode(true);
node.id = ""; // Don't forget :)
// modify node contents with DOM manipulation
container.appendChild(node);
</script>
...
<div id="templates">
<div id="tmp_audio">
Play
Mute
<div class="progressBarOuter">
<div class="bytesLoaded"></div>
<div class="progressBar"></div>
</div>
<div class="currentTime">0:00</div>
<div class="totalTime">0:00</div>
</div>
</div>
Update: Note that I've converted the id attributes in the template to class attributes. This is to avoid having multiple elements on your page with the same ids. You probably don't even need the classes. You can access elements with:
node.getElementsByTagName("div")[4].innerHTML =
format(data.currentTime);
Alternatively, you can act on the HTML of the template:
<script type="text/javascript">
var tmp = document.getElementById("tmp_audio").innerHTML;
// modify template HTML with token replacement
container.innerHTML += tmp;
</script>

Shove the entire thing into a JS variable:
var html = 'Play';
html += 'Mute';
html += '<div id="progressBarOuter"><div id="bytesLoaded"></div><div id="progressBar"></div></div>';
html += '<div id="currentTime">0:00</div>';
html += '<div id="totalTime">0:00</div>';
Then:
document.getElementById("parentElement").innerHTML = html;
if you want theN:
document.getElementById("totalTime").innerHTML = "5:00";

You can use
<script type="text/javascript">
function appendHTML() {
var wrapper = document.createElement("div");
wrapper.innerHTML = '\
Play\
Mute\
<div id="progressBarOuter"> \
<div id="bytesLoaded"></div>\
<div id="progressBar"></div>\
</div>\
<div id="currentTime">0:00</div>\
<div id="totalTime">0:00</div>\
';
document.body.appendChild(wrapper);
}
</script>

If you live in 2019 and beyond read here.
With JavaScript es6 you can use string literals to create templates.
create a function that returns a string/template literal
function videoPlayerTemplate(data) {
return `
<h1>${data.header}</h1>
<p>${data.subheader}</p>
Play
Mute
<div id="progressBarOuter">
<div id="bytesLoaded"></div>
<div id="progressBar"></div>
</div>
<time id="currentTime">0:00</time>
<time id="totalTime">0:00</time>
`
}
Create a JSON object containing the data you want to display
var data = {
header: 'My video player',
subheader: 'Version 2 coming soon'
}
add that to whatever element you like
const videoplayer = videoPlayerTemplate(data);
document.getElementById('myRandomElement').insertAdjacentHTML("afterbegin", videoplayer);
You can read more about string literals here

edit: HTML import is now deprecated.
Now with Web Components you can inject HTML using an HTML import.
The syntax looks like this:
<link rel="import" href="component.html" >
This will just load the content of the html file in the href attribute inline in the order it appears. You can any valid html in the loaded file, so you can even load other scripts if you want.
To inject that from JavaScript you could do something of the likes of:
var importTag = document.createElement('link');
importTag.setAttribute('rel', 'import');
importTag.setAttribute('href', 'component.html');
document.body.appendChild(importTag);
At the time I am writing this, Chrome and Opera support HTML imports. You can see an up to date compatibility table here http://caniuse.com/#feat=imports
But don't worry about browsers not supporting it, you can use it in them anyway with the webcomponentsjs polyfill.
For more info about HTML imports check http://webcomponents.org/articles/introduction-to-html-imports/

If you don't need any validation for your syntax (which is what makes createElement() so nice) then you could always default to simply setting the innerHTML property of the element you want to insert your markup inside of.
Personally, I would stick with using createElement(). It is more verbose but there are far less things to worry about that way.

If performance is a concern, stay away from innerHTML. You should create the whole object tree using document.createElement() as many times as needed, including for nested elements.
Finally, append it to the document with one statement, not many statements.
In my informal testing over the years, this will give you the best performance (some browsers may differ).
If HTML is ever declared in a variable, it should be simple and for a very specific purpose. Usually, this is not the right approach.

here's 2 possible cases :
Your HTML is static
Your HTML is dynamic
solution 1
In this case, wrap your HTML in double quotes, make it a string and save it in a variable. then push it inside HTML, here's a demo 👇
HTML
<div id="test"></div>
JavaScript
let selector = document.querySelector("#test");
let demo_1 = "<div id='child'> hello and welcome</div>"
selector.innerHTML = demo_1;
solution 2
In this case, wrap your HTML in back ticks, make it a template literal and save it in a variable. then push it inside HTML,
here, you can use variables to change your content. here's a demo 👇
HTML
<div id="test"></div>
JavaScript
let selector = document.querySelector("#test");
let changes = 'hello and welcome'
let demo_1 = `<div id='child'>${changes}</div>`
selector.innerHTML = demo_1;

You can concatenate raw HTML strings (being careful to escape text and prevent XSS holes), or you can rewrite jQuery (or something similar)

I have a situation where I pass text into a third party library, but if my model isPrivate, I'd like to add an element to the text.
return { id: item.id, text: (item.isPrivate == true) ? "<i class=\"icon-lock\" title=\"Private group.\"></i> " + item.label : item.label };
This creates issues with the way the third party library builds up its markup.
This is never a good idea, but third party libraries are there so that we don't have to write everything ourselves. In a situation like this, you have to rely on passing markup though javascript.
When i find a proper solution to this, I will give you an update