Adding javascript to onDocumentReady issue - javascript

I have a div on my page defined as follows:
<div id="scripts">
</div>
I want to dynamically change the contents of the div and load in some scripts using jQuery. I am doing it like this:
$('#scripts').html('<script language="JavaScript">pn = "landing page"; '+
'cms_1 = "content"; '+
'cms_2 = "promotional "; '+
'cms_3 = "campaign"; '+
'cms_s = "blk:us:dc"; '+
'cms_env = "dev"; '+
'cms_country = "USA"; '+
'<\/script>');
This is in the document.Ready function. However, when I view the source after the page is loaded, the div appears empty and I do not see the script tags. I thought that the script wasn't getting added but when I add alert("done"); to the script. I get the alert which tells me that the code is executed.
Why can't I see the changes made when I view the source? Is the Source html rendered before the document.ready function?

The html function from jquery internally uses the innerHTML property of the browser when available. In general, script blocks inserted via innerHTML don't get executed almost in any browser.
Try creating a script tag with the content and appending it to the document instead, e.g.
var script=document.createElement('script');
script.type='text/javascript';
script.html(...);
$("#scripts").append(script);
After seeing your motivation in the comment, I have to add : although you can later physically remove a script tag from the site, this won't have the effect of unloading its content (e.g. functions defined in the script). The only way to achieve that without refreshing the page is to encapsulate the objects defined in it and delete them manually. This is of course only possible if the content of the script was designed upfront in such a way.

Related

Parse a HTML String with JS without triggering any page loads?

As this answer indicates, a good way to parse HTML in JavaScript is to simply re-use the browser's HTML-parsing capabilities like so:
var el = document.createElement( 'html' );
el.innerHTML = "<html><head><title>titleTest</title></head><body><a href='test0'>test01</a><a href='test1'>test02</a><a href='test2'>test03</a></body></html>";
// process 'el' as desired
However, this triggers loading extra pages for certain HTML strings, for example:
var foo = document.createElement('div')
foo.innerHTML = '<img src="http://example.com/img.png">';
As soon as this example is run, the browser attempts to load the page:
How might I process HTML from JavaScript without this behavior?
I don't know if there is a perfect solution for this, but since this is merely for processing, you can before assigning innerHTMl replace all src attributes to be notSrc="xyz.com", this way it wont be loaded, and if you need them later in processing you can account for this.
The browser mainly will load images, scripts, and css files, this will fix the first 2, the css can be done by replacing the href attribute.
If you want to parse HTML response without loading any unnecessary resources like images or scripts inside, use DOMImplementation’s createHTMLDocument() to create new document which is not connected to the current one parsed by the browser and behaves as well as normal document.

Rails + JQuery: Getting to a sibling div from script

I have a rails partial that renders this html:
<div class="content"></div>
<script>
// load the content here and get the adjacent div and populate it.
</script>
This partial template gets embedded in the main document by the server and also several times as response to AJAX requests. So the page has several instances of this partial.
Whenever my script executes I want only the div adjacent to the script to be affected.
So I am hoping if I could get to the script, I can get to the div. I use jQuery as well and I also use several async scripts (this prevents me from using the last executed script)
I could get to the adjacent div through document.currentScript , the problem is some browsers don't support it.
Then, is the only way to do is to create some sort of a UUID ID for the div and access it by Id from the DOM?
I really wished div supported onload, but sadly not.
You can create the element immediately after the <script> (document.write) and find the .content relative to it.
(function(){
var id = 'id' + (new Date().getTime());
document.write('<div id="'+id+'"></div>');
var elem = document.getElementById(id);
var content = elem.previousElementSibling.previousElementSibling;
content.innerHTML = 'NEW CONTENT';
})();
Example jsbin
If each partial belongs to an ActiveRecord model, use dom_id function available in Rails - in the div and in the corresponding script.
Use jQuery replaceWith:
<div id="div_id" class="content"></div>
<script>
# on document load
$('#div_id').replaceWith(new_content);
</script>

Running the javascript code present on another html page through jquery

It might be a noob questions but I have just started using jquery.
My basic requirement to extract the link which is there in the javascript code present in another html (code is embedded in the html page and not in a seperate file).
The link is also present as a href attribute of <a> tag inside a tag, just to add if it is easier to extract it from there (I am using chrome so I think it considers there are no child nodes of <noscript> tag)
After this I tried doing an ajax request to the html page (using $.ajax) thinking it will run the scripts on the page but got the html code of the page in return :S . I have also heard of something called evalscripts:true but not sure if that will work here or how to use it?
I have also tried to search for the link in html code returned by my html page by using the "contains" operation of jquery.
I am doing all this to create a greasemonkey script. Please suggest
Example Code:
This is a function present inside the html of that page:
function fun() {
obj = new pollingObj('argument', "a link I want to extract comes here");
}
I want to extract the link: "a link I want to extract comes here" and then open it.on my page where I am running my jquery script
This link is also present like this on the html page:
<noscript>
blabla
</noscript>
Also is it possible to run the javascripts present on that page if the link extraction is not possible?
If you're able to get the html code of the page successfully via .ajax, and the data you want is in the HTML code, it's not worth the effort to bother with trying to run the scripts. Just access the URL through the DOM:
// ajax success function
success: function(html) {
var anchorCode = $(html)
// this assumes that noscript is a top-level element
// otherwise, use .find('noscript')
.filter('noscript')
.text(); // get the code for the anchor tag, as a string
var myLink = $(anchorCode).attr('href');
// do something with myLink
}
Edit: It turns out that jQuery is a little funny in the way it deals with noscript tags - inner tags don't appear to be considered part of the DOM, so you need to grab the text content of the tag and then use jQuery to DOM-ify it. See updated code above.

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.)

Dynamically inserting javascript into HTML that uses document.write

I am currently loading a lightbox style popup that loads it's HTML from an XHR call. This content is then displayed in a 'modal' popup using element.innerHTML = content This works like a charm.
In another section of this website I use a Flickr 'badge' (http://www.elliotswan.com/2006/08/06/custom-flickr-badge-api-documentation/) to load flickr images dynamically. This is done including a script tag that loads a flickr javascript, which in turn does some document.write statments.
Both of them work perfectly when included in the HTML. Only when loading the flickr badge code inside the lightbox, no content is rendered at all. It seems that using innerHTML to write document.write statements is taking it a step too far, but I cannot find any clue in the javascript implementations (FF2&3, IE6&7) of this behavior.
Can anyone clarify if this should or shouldn't work? Thanks.
In general, script tags aren't executed when using innerHTML. In your case, this is good, because the document.write call would wipe out everything that's already in the page. However, that leaves you without whatever HTML document.write was supposed to add.
jQuery's HTML manipulation methods will execute scripts in HTML for you, the trick is then capturing the calls to document.write and getting the HTML in the proper place. If it's simple enough, then something like this will do:
var content = '';
document.write = function(s) {
content += s;
};
// execute the script
$('#foo').html(markupWithScriptInIt);
$('#foo .whereverTheDocumentWriteContentGoes').html(content);
It gets complicated though. If the script is on another domain, it will be loaded asynchronously, so you'll have to wait until it's done to get the content. Also, what if it just writes the HTML into the middle of the fragment without a wrapper element that you can easily select? writeCapture.js (full disclosure: I wrote it) handles all of these problems. I'd recommend just using it, but at the very least you can look at the code to see how it handles everything.
EDIT: Here is a page demonstrating what sounds like the effect you want.
I created a simple test page that illustrates the problem:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<title>Document Write Testcase</title>
</head>
<body>
<div id="container">
</div>
<div id="container2">
</div>
<script>
// This doesn't work!
var container = document.getElementById('container');
container.innerHTML = "<script type='text/javascript'>alert('foo');document.write('bar');<\/script>";
// This does!
var container2 = document.getElementById('container2');
var script = document.createElement("script");
script.type = 'text/javascript';
script.innerHTML = "alert('bar');document.write('foo');";
container.appendChild(script);
</script>
</body>
</html>
This page alerts 'bar' and prints 'foo', while I expected it to also alert 'foo' and print 'bar'. But, unfortunately, since the script tag is part of a larger HTML page, I cannot single out that tag and append it like the example above. Well, I can, but that would require scanning innerHTML content for script tags, and replacing them in the string by placeholders, and then inserting them using the DOM. Sounds not that trivial.
Use document.writeln(content); instead of document.write(content).
However, the better method is using the concatenation of innerHTML, like this:
element.innerHTML += content;
The element.innerHTML = content; method will replace the old content with the new one, which will overwrite your element's innerHTML!
Whereas using the the += operator in element.innerHTML += content will append your text after the old content. (similar to what document.write does.)
document.write is about as deprecated as they come. Thanks to the wonders of JavaScript, though, you can just assign your own function to the write method of the document object which uses innerHTML on an element of your choosing to append the supplied content.
Can I get some clarification first to make sure I get the problem?
document.write calls will add content to the markup at the point in the markup at which they occur. For example if you include document.write calls in a function but call the function elsewhere, the document.write output will happen at the point in the markup the function is defined not where it is called.
Therefore for this to work at all the Flickr document.write statements will need to be part of the content in element.innerHTML = content. Is this definitely the case?
You might quickly test if this should work at all by adding a single and simple document.write call in the content that is set as the innerHTML and see what this does:
<script>
var content = "<p>1st para</p><script>document.write('<p>2nd para</p>');</script>"
element.innerHTML = content;
</script>
If that works, the concept of document.write working in content set as the innerHTML of an element might just work.
My gut feeling is that it won't work, but it should be pretty straightforward to test the concept.
So you're using a DOM method to create a script element and append that to an existing element and this then causes the content of the appended script element to execute? That sounds good.
You say that the script tag is part of a larger HTML page and therefore cannot be singled out. Can you not give the script tag an ID and target it? I'm probably missing something obvious here.
In theory, yes, I can single out a script tag that way. The problem is that we potentially have dozens of situations where this occurs, so I am trying to find some cause or documentation of this behavior.
Also, the script tag does not seem to be a part of the DOM anymore after it gets loaded. In our environment, my container div remains empty, so I cannot fetch the script tag. It should work, though, because in my example above the script does not get executed, but is still part of the DOM.

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