Adding the method to the facility through prototype

[morde]

The code below shall designate a type object Image with prototype three new methods: protocol()♪ host() and pathname()♪
The fireFox browser is going well. Chrome makes the following mistake:

Uncaught TypeError: document.i1.protocol is not a function

Accordingly, and other functions document.i1.host and document.i1.path Not implemented.

What's the problem and how do we solve it?

function pr() {
    a = this.src.split(':');
    return a[0] + ':';
}
function ho() {

a = this.src.split(':');

path = a[1].split('/');

return path[2];

}
function pa() {

path = this.src.split('/');

path[0] = '';

path[2] = '';

return path.join('/').split('///').join('/');

}
Image.prototype.protocol = pr;

Image.prototype.host = ho;

Image.prototype.pathname = pa;
document.write("<IMG NAME=i1 SRC='img1.jpg'><BR>");

document.write(document.i1.src + "<BR>");

document.write(document.i1.protocol() + "<BR>");

document.write(document.i1.host() + "<BR>");

document.write(document.i1.pathname() + "<BR>");

[gionna]

Received <img> (e.g. by document.getElementById('img') or new Image()has a type HTMLImageElement♪ Accordingly, adding new methods is necessary in his prototype.

Example:

function log(info) {
    document.body.innerHTML += info + "<br/>";
}
HTMLImageElement.prototype.protocol = function() {

log("Protocol is called");

};
var img = document.getElementById('img');

log("Got image: " + img.constructor.name);

img.protocol();
var newImage = new Image();

log("New image: " + newImage.constructor.name);

newImage.protocol();

<img id='img' /><br/>