ES 5 Configurable Properties

img_src_override.js

// http://jsfiddle.net/s4ex1dtj/
"use strict";
var myImage = new Image();
Object.defineProperty(myImage, "src", { 
    get: function () { return 'foo'; }, 
    set: function (val) { alert(val); } });
console.log(myImage.src); // Logs value 'foo'
myImage.src = "new"; // alerts value 'new'

// newImage does not have a redefined setter since our previous property
// definition was only on the myImage instance
var newImage = new Image();
console.log(newImage.src); // Logs browser src getter value

// Fix newImage and all existing and future images using the prototype
Object.defineProperty(HTMLImageElement.prototype, "src", { 
    get: function () { return 'foo'; }, 
    set: function (val) { alert(val); } });
console.log(newImage.src); // Logs value 'foo'
newImage.src = "yay!"; // alerts value 'yay!'

img_src_set.js

var myImage = new Image();
console.log(myImage.src); // Log the browsers natural src getter
myImage.src = "http://wwww.foo.com/myImage.png"; // Use the browsers natural src setter
console.log(myImage.src); // Log the browsers natural src getter after setting

img_src_wrap.js

// http://jsfiddle.net/2aetdjj9/
// Get the property descriptor for the original browser src property
var propertyDescriptorSrc = Object.getOwnPropertyDescriptor(HTMLImageElement.prototype, "src");
alert(propertyDescriptorSrc.get); // alerts function set() { [native code] }

// Wrap the property descriptor and add some logging
Object.defineProperty(HTMLImageElement.prototype, "src", { 
    get: function get_src() {
        var val = propertyDescriptorSrc.get.call(this);
        alert('getting src: ' + val);
        return val;
    }, 
    set: function (val) {
        alert('setting src to: ' + val);
        propertyDescriptorSrc.set.call(this, val);
    }
});

var myImage = new Image();
myImage.src; // alert's the source in our pass through getter

// Now lets verify our pass through setter
myImage.src = 'https://camo.githubusercontent.com/eb464a60a4a47f8b600aa71bfbc6aff3fe5c5392/68747470733a2f2f7261772e6769746875622e636f6d2f766f6f646f6f74696b69676f642f6c6f676f2e6a732f6d61737465722f6a732e706e67';

// Verify the native src was actually set (note: 'target' is defined in the fiddle)
document.getElementById('target').appendChild(myImage);