Develop Reference

Force JS cache clearing without server-side coding

I'm looking to clear the cache on some JavaScript files on my login page. Our web language is pretty archaic, and I'm stuck using it. No PHP, Rails, or anything fun or fancy.
Looking to clear cache on JS files
1. I can't use server-side code.
2. I can't manually append a query string.
3. I found the meta tags mentioned, but noticed that strictly referred the caching the HTML.
My only thought was to use JavaScript in the header to manipulate the text of the HTML document before it loads the files in the tags that occur further down the page. Though I was unable to get this to work successfully. Any ideas?

I'm assuming you currently have something like this in your code:
<script type="text/javascript" src="/site/js/script.js"></script>
If you can't change that, you're stuck. The browser is going to load that as soon as it sees the tag. There's not a reliable way to stop the browser from doing that, or to manipulate the tag before the browser acts on it.
If you can change it, though, the most obvious solution to me is to take it out, and instead dynamically inject a script tag with a cache-busting URL. For example (untested, but you get the idea):
<script>
var scriptUrl = "/site/js/script.js",
cacheBustingUrl = scriptUrl + "?" + Date.now(),
newScriptElement = document.createElement("script")
;
newScriptElement.setAttribute("src", cacheBustingUrl);
document.body.appendChild(newScriptElement);
</script>
This should append a new script element like <script src="/site/js/script.js?1404918388711"></script> to the end of the page, which the browser will load like any other script tag.
If you already have jQuery, by the way, this is a little more succinct:
<script>
var scriptUrl = "/site/js/script.js",
cacheBustingUrl = scriptUrl + "?" + Date.now()
;
$("<script>").attr("src", cacheBustingUrl).appendTo(document.body);
</script>

AngularJS - inject trusted code from loaded content

I've hooked up a lazy loader in Angular. It pulls in full templates and extracts key information from that full template in order to populate a partial. This full page template has script tags which load in and then register with the existing app. All of this works fine. My problem is that I'd like to remove the only use of jQuery in this approach.
The root issue is that the JS inside of something.js doesn't execute when using $element.html(), but it does execute when using $.html(), despite the script tag being placed in the DOM in both approaches.
Working code, including lazy loader and post-bootstrap registration of lazy-loaded JS:
$http.get("/path/to/file.html").success(function(response) {
// response is a full HTML page including <doctype>
var partial = getOnlyWhatWeNeed(response);
// partial is now something like: '<script type="text/javascript" src="/path/to/something.js"></script><div ng-controller="somethingCtrl">{{something}}</div>'
// i'd like the following to not rely on full jQuery.
$("#stage").html(partial);
$("#stage").html($compile(partial)($scope)); // it is necessary to do it once before compile so that the <script> tags get dropped in and executed prior to compilation.
});
I've tried what seems like the logical translation:
$element.html($compile(partial)($scope));
and the DOM is created properly, but the JS inside of the loaded <script> tag doesn't actually execute. My research suggested this was an $sce issue, so I tried:
$element.html($compile($sce.trustAsHtml(partial)($scope));
but i get the same result. the DOM is fine, but the JS doesn't actually execute and so I get undefined controller issues.
I've tried playing with $sce.JS and $sce.RESOURCE_URL but the docs didnt elaborate much so I'm not sure I know whether or not what I'm trying is even right.
I've also tried $element[0].innerHTML but I get the same result as $element.html().
Preemptive disclaimer: I can trust the incoming HTML/JS. I know it's inadvisable. This isn't my baby and it is much more complicated than I explained so please try to stay on topic so other people in this position may not have as hard of a time as I am :)
The $http.get happens in a provider, and the $element.html happens in a directive. I consolidated them to remove noise from the problem.

Jquery will find any script tags and evaluate them (either a direct eval or appending them to the head for linked scripts) when calling html(), see this answer. I'm assuming angular's jquery lite doesn't do this. You would need to effectively replicate what jquery is doing and look for script tags in the html you are appending.
Something like this (although I haven't tested it):
$http.get("/path/to/file.html").success(function(response) {
// response is a full HTML page including <doctype>
var partial = getOnlyWhatWeNeed(response);
// partial is now something like: '<script type="text/javascript" src="/path/to/something.js"></script><div ng-controller="somethingCtrl">{{something}}</div>'
var d = document.createElement('div');
d.innerHTML = partial;
var scripts = d.getElementsByTagName('script');
for (var i = 0; i < scripts.length; i++) {
document.head.appendChild(scripts[0]);
}
$("#stage").html($compile(partial)($scope)); // it is necessary to do it once before compile so that the <script> tags get dropped in and executed prior to compilation.
});
This is far from an ideal solution as it gives you no guarantee of when things are loaded and doesn't really handle dependencies across scripts. If you can control the templates it would be simpler to remove the scripts from them and load them independently.

Recommended method to locate the current script?

I am writing a script that needs to add DOM elements to the page, at the place where the script is located (widget-like approach).
What is the best way to do this?
Here are the techniques I am considering:
Include an element with an id="Locator" right above the script. Issues:
I don't like the extra markup
If I reuse the widget in the page, several elements will have the same "Locator" id. I was thinking about adding a line in the script to remove the id once used, but still...
Add an id to the script. Issues:
even though it seems to work, the id attribute is not valid for the script element
same issue as above, several elements will have the same id if I reuse the script in the page.
Use getElementsByTagName("script") and pick the last element. This has worked for me so far, it just seems a little heavy and I am not sure if it is reliable (thinking about deferred scripts)
document.write: not elegant, but seems to do the job.
[Edit] Based on the reply from idealmachine, I am thinking about one more option:
Include in the script tag an attribute, for example goal="tabify".
Use getElementsByTagName("script") to get all the scripts.
Loop through the scripts and check the goal="tabify" attribute to find my script.
Remove the goal attribute in case there's another widget in the page.
[Edit] Another idea, also inspired by the replies so far:
Use getElementsByTagName("script") to get all the scripts.
Loop through the scripts and check innerHTML to find my script.
At the end of the script, remove the script tag in case there's another widget in the page.

Out of the box : document.currentScript (not supported by IE)

I've worked for OnlyWire which provides, as their main service, a widget to put on your site.
We use the var scripts = document.getElementsByTagName("script"); var thisScript = scripts[scripts.length - 1]; trick and it seems to work pretty well. Then we use thisScript.parentNode.insertBefore(ga, thisScript); to insert whatever we want before it, in the DOM tree.
I'm not sure I understand why you consider this a "heavy" solution... it doesn't involve iteration, it's a pure cross-browser solution which integrates perfectly.

This works with multiple copies of same code on page as well as with dynamically inserted code:
<script type="text/javascript" class="to-run">
(function(self){
if (self == window) {
var script = document.querySelector('script.to-run');
script.className = '';
Function(script.innerHTML).call(script);
} else {
// Do real stuff here. self refers to current script element.
console.log(1, self);
}
})(this);
</script>

Either document.write or picking the last script element will work for synchronously loaded scripts in the majority of web pages. However, there are some options I can think of that you did not consider to allow for async loading:
Adding a div with class="Locator" before the script. HTML classes has the advantage that duplicates are not invalid. Of course, to handle the multiple widget case, you will want to change the element's class name when done adding the HTML elements so you do not add them twice. (Note that it is also possible for an element to be a member of multiple classes; it is a space-separated list.)
Checking the src of each script element can ensure that tracking code (e.g. Google Analytics legacy tracking code) and other scripts loaded at the very end of the page will not prevent your script from working properly when async loading is used. Again, to handle the multiple widget case, you may need to remove the script elements when done with them (i.e. when the desired code has been added to the page).
One final comment I will make (although you may already be aware of this) is that when coding a widget, you need to declare all your variables using var and enclose all your code within: (JSLint can help check this)
(function(){
...
})();
This has been called a "self-executing function" and will ensure that variables used in your script do not interfere with the rest of the Web page.

Whether you drop a <script> tag in or a <div class="mywidget">, you're adding something to the markup. Personally, I prefer the latter as the script itself is only added once. Too many scripts in the page body can slow down the page load time.
But if you need to add the script tag where the widget is going to be, I don't see what's wrong with using document.write() to place a div.

I just found another method that seems to answer my question:
How to access parent Iframe from javascript
Embedding the script in an iframe allows to locate it anytime, as the script always keeps a reference to its own window.
I vote this the best approach, as it'll always work no matter how many times you add the script to the page (think widget). You're welcome to comment.
What pushed me to consider iframes in the first place was an experiment I did to build a Google gadget.

In many cases this work well (hud.js is the name of the scipt):
var jsscript = document.getElementsByTagName("script");
for (var i = 0; i < jsscript.length; i++) {
var pattern = /hud.js/i;
if ( pattern.test( jsscript[i].getAttribute("src") ) )
{
var parser = document.createElement('a');
parser.href = jsscript[i].getAttribute("src");
host = parser.host;
}
}

Also you can add individual script's name inside them.
either inside some js-script
dataset['my_prefix_name'] = 'someScriptName'
or inside HTML - in the <script> tag
data-my_prefix_name='someScriptName'
and next search appropriate one by looping over document.scripts array:
... function(){
for (var i = 0, n = document.scripts.length; i < n; i++) {
var prefix = document.scripts[i].dataset['my_prefix_name']
if (prefix == 'whatYouNeed')
return prefix
}
}

I haven't had access to internet explorer since forever, but this should work pretty much everywhere:
<script src="script.js"
data-count="30"
data-headline="My headline"
onload="uniqueFunctionName(this)"
defer
></script>
and inside script.js:
window.uniqueFunctionName = function (currentScript) {
var dataset = currentScript.dataset
console.log(dataset['count'])
console.log(dataset['headline'])
}

what happens when you use javascript to insert a javascript widget?

can anyone explain what happens when you use javascript to insert a javascript based widget?
here's my js code:
var para = document.getElementsByTagName("p");
var cg = document.createElement("div");
cg.setAttribute("class", "twt");
cg.innerHTML='<a href="http://twitter.com/share" class="twitter-share-button"
data-count="vertical" data-via="xah_lee">Tweet</a>
<script type="text/javascript" src="http://platform.twitter.com/widgets.js"></script>';
document.body.insertBefore(cg, para[1]);
it inserts the twitter widget, before the first paragraph. As you can see above, the twitter widget calls for a javascript that shows how many time the page has been tweeted.
doesn't work in Firefox, Chrome, but semi-works in IE8. What should be the expected behavior when this happens? Does the newly inserted js code supposed to execute? If so, how's it differ from if the code is on the page itself?

In order to execute the JS code you insert into a DIV via innerHTML, you need to do something like the following (courtesy of Yuriy Fuksenko at http://www.coderanch.com/t/117983/HTML-JavaScript/Execute-JavaScript-function-present-HTML )
function setAndExecute(divId, innerHTML) {
var div = document.getElementById(divId);
div.innerHTML = innerHTML;
var x = div.getElementsByTagName("script");
for (var i=0;i<x.length;i++) {
eval(x[i].text);
}
}
A slightly more advanced approach is here: http://zeta-puppis.com/2006/03/07/javascript-script-execution-in-innerhtml-the-revenge/ - look for <script> tags, take their con­tent and create a new ele­ment into the <head>.

innerHTML does not work to insert script tags (because the linked script, in most browsers, will fail to execute). Really, you should insert the script tag once on the server side and insert only the link at the location of each post (that is, if you are adding this to a blog home page that shows multiple posts, each with their own URLs).
If, for some reason, you decide that you must use one snippet of JavaScript to do it all, at least import the tweet button script in a way that will work, for example, the Google Analytics way or the MediaWiki way (look for the importScriptURI function). (Note that I do not know the specifics of the tweet button, so it might not even work.)

How do I get the original innerHTML source without the Javascript generated contents?

Is it possible to get in some way the original HTML source without the changes made by the processed Javascript? For example, if I do:
<div id="test">
<script type="text/javascript">document.write("hello");</script>
</div>
If I do:
alert(document.getElementById('test').innerHTML);
it shows:
<script type="text/javascript">document.write("hello");</script>hello
In simple terms, I would like the alert to show only:
<script type="text/javascript">document.write("hello");</script>
without the final hello (the result of the processed script).

I don't think there's a simple solution to just "grab original source" as it'll have to be something that's supplied by the browser. But, if you are only interested in doing this for a section of the page, then I have a workaround for you.
You can wrap the section of interest inside a "frozen" script:
<script id="frozen" type="text/x-frozen-html">
The type attribute I just made up, but it will force the browser to ignore everything inside it. You then add another script tag (proper javascript this time) immediately after this one - the "thawing" script. This thawing script will get the frozen script by ID, grab the text inside it, and do a document.write to add the actual contents to the page. Whenever you need the original source, it's still captured as text inside the frozen script.
And there you have it. The downside is that I wouldn't use this for the whole page... (SEO, syntax highlighting, performance...) but it's quite acceptable if you have a special requirement on part of a page.
Edit: Here is some sample code. Also, as #FlashXSFX correctly pointed out, any script tags within the frozen script will need to be escaped. So in this simple example, I'll make up a <x-script> tag for this purpose.
<script id="frozen" type="text/x-frozen-html">
<div id="test">
<x-script type="text/javascript">document.write("hello");</x-script>
</div>
</script>
<script type="text/javascript">
// Grab contents of frozen script and replace `x-script` with `script`
function getSource() {
return document.getElementById("frozen")
.innerHTML.replace(/x-script/gi, "script");
}
// Write it to the document so it actually executes
document.write(getSource());
</script>
Now whenever you need the source:
alert(getSource());
See the demo: http://jsbin.com/uyica3/edit

A simple way is to fetch it form the server again. It will be in the cache most probably. Here is my solution using jQuery.get(). It takes the original uri of the page and loads the data with an ajax call:
$.get(document.location.href, function(data,status,jq) {console.log(data);})
This will print the original code without any javascript. It does not do any error handling!
If don't want to use jQuery to fetch the source, consult the answer to this question: How to make an ajax call without jquery?

Could you send an Ajax request to the same page you're currently on and use the result as your original HTML? This is foolproof given the right conditions, since you are literally getting the original HTML document. However, this won't work if the page changes on every request (with dynamic content), or if, for whatever reason, you cannot make a request to that specific page.

Brute force approach
var orig = document.getElementById("test").innerHTML;
alert(orig.replace(/<\/script>[.\n\r]*.*/i,"</script>"));
EDIT:
This could be better
var orig = document.getElementById("test").innerHTML + "<<>>";
alert(orig.replace( /<\/script>[^(<<>>)]+<<>>/i, "<\/script>"));

If you override document.write to add some identifiers at the beginning and end of everything written to the document by the script, you will be able to remove those writes with a regular expression.
Here's what I came up with:
<script type="text/javascript" language="javascript">
var docWrite = document.write;
document.write = myDocWrite;
function myDocWrite(wrt) {
docWrite.apply(document, ['<!--docwrite-->' + wrt + '<!--/docwrite-->']);
}
</script>
Added your example somewhere in the page after the initial script:
<div id="test">
<script type="text/javascript"> document.write("hello");</script>
</div>
Then I used this to alert what was inside:
var regEx = /<!--docwrite-->(.*?)<!--\/docwrite-->/gm;
alert(document.getElementById('test').innerHTML.replace(regEx, ''));

If you want the pristine document, you'll need to fetch it again. There's no way around that. If it weren't for the document.write() (or similar code that would run during the load process) you could load the original document's innerHTML into memory on load/domready, before you modify it.

I can't think of a solution that would work the way you're asking. The only code that Javascript has access to is via the DOM, which only contains the result after the page has been processed.
The closest I can think of to achieve what you want is to use Ajax to download a fresh copy of the raw HTML for your page into a Javascript string, at which point since it's a string you can do whatever you like with it, including displaying it in an alert box.

A tricky way is using <style> tag for template. So that you do not need rename x-script any more.
console.log(document.getElementById('test').innerHTML);
<style id="test" type="text/html+template">
<script type="text/javascript">document.write("hello");</script>
</style>
But I do not like this ugly solution.

I think you want to traverse the DOM nodes:
var childNodes = document.getElementById('test').childNodes, i, output = [];
for (i = 0; i < childNodes.length; i++)
if (childNodes[i].nodeName == "SCRIPT")
output.push(childNodes[i].innerHTML);
return output.join('');