Chrome-extension Javascript to detect dynamically-loaded content

Question

I\'m implementing a chrome extension app. I want to replace href attribute in tag (on my webapp\'s homepage) with \"#\". The problem is that the tag might

Answer 1

The accepted answer is outdated. As of now, 2019, Mutation events are deprecated. People should use MutationObserver. Here is how to use it in pure javascript:

// Select the node that will be observed for mutations
var targetNode = document.getElementById('some-id');

// Options for the observer (which mutations to observe)
var config = { attributes: true, childList: true, subtree: true };

// Callback function to execute when mutations are observed
var callback = function(mutationsList, observer) {
    for(var mutation of mutationsList) {
        if (mutation.type == 'childList') {
            console.log('A child node has been added or removed.');
        }
        else if (mutation.type == 'attributes') {
            console.log('The ' + mutation.attributeName + ' attribute was modified.');
        }
    }
};

// Create an observer instance linked to the callback function
var observer = new MutationObserver(callback);

// Start observing the target node for configured mutations
observer.observe(targetNode, config);

// Later, you can stop observing
observer.disconnect();

Answer 2

There are two ways to do it,

First solution is handling the ajax requests

There is a .ajaxComplete() function in jQuery which handles all ajax request on page.

In content script,

var actualCode = '(' + function() {
    $(document).ajaxComplete(function() { 
      alert('content has just been changed, you should change href tag again');
      // chaging href tag code will be here      
    });
} + ')();';
var script = document.createElement('script');
script.textContent = actualCode;
(document.head||document.documentElement).appendChild(script);
script.parentNode.removeChild(script);

Second solution is listening the content changes

This is possible with mutation events, again in content script

$(document).bind("DOMSubtreeModified", function() {
    alert("something has been changed on page, you should update href tag");
});

You might use some different selector to restrict the elements that you're controling the changes.

$("body").bind("DOMSubtreeModified", function() {}); // just listen changes on body content

$("#mydiv").bind("DOMSubtreeModified", function() {}); // just listen changes on #mydiv content