Chrome browser extension that detects hashtags in page

As personal project I would like to build a Chrome extension that will find all hashtags on a page. I don't much about JS or jquery so I wonder how I should approach this?

EDIT: The Chrome Extension injects javascript after the page has loa开发者_C百科ded, but I need to scan the whole document for a hashtag. It is looking through the whole document that I am not sure how to do.

Thanks!

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If you mean simply anchor tags with a href that has a # in it then:

var aTags = document.getElementsByTagName("a");
for(var index = 0; index < aTags.length; index++){
    if(aTags[index].href.indexOf("#") != -1){
        alert("found one");
    }
}

Or if you want something more general, one way to return the entire webpage is simply:

document.body.innerHTML  //A string containing all the code/text inside the body of the webpage.

And then you can do some indexOf or a regex search/replace depending on what you want to do specifically.

But if you know that the hashtag you are looking for is always in some container like a anchor or even just a div with particular class then I would go with that instead of working with the entire page. Here is a list of useful methods to parse up a webpage:

document.getElementsByTagName("a");  //already mentioned
document.getElementsById("id");
document.getElementsByName("name");
//and a custom function to get elements by class name(I did  not write this)
function getElementsByClass(searchClass, domNode, tagName)
{ 
if (domNode == null) domNode = document;
if (tagName == null) tagName = '*';
var el = new Array();
var tags = domNode.getElementsByTagName(tagName);
var tcl = " "+searchClass+" ";
for(i=0,j=0; i<tags.length; i++)
{ 
    var test = " " + tags[i].className + " ";
    if (test.indexOf(tcl) != -1)
    {
        el[j++] = tags[i];
    }
} 
return el;
}