Question

Here are two JavaScript classes written by others, I need to use both of them:

1. filter.js
2. validator.js

I need to mix them up into a single class – it could be Validator or Filter class, or some class I define but I have to do this after Validator Filter initialized.

Answer 1

Since validator constructor is empty already you could do:

Filter.prototype = new Validator();
Filter.prototype.constructor = Filter;

Filter.prototype.modify = ...

...

... means adding all the filter methods to filter prototype like you are doing in the filter file.

But I need do this after Filter and Validator initialized

You could try something like this then:

    var a = new Validator(),
        b = new Filter(); //They are initialized

    var tmp = Filter.prototype,
        key;

    Filter.prototype = a;

    for( key in tmp ) {
    Filter.prototype[key] = tmp[key];
    }

    Filter.prototype.constructor = Filter;

b ( a Filter instance ) will now have all Filter and Validator methods