Intercepting JavaScript methods

If for some reason you want to intercept any JavaScript method, so whenever this method is called, you want to inject a piece of code to be executed either before or after it..

for example the following code, will log to console each new item is pushed to any array in the system, also it will warn us if any array goes beyond the 1000 element...

// cache a  reference for original
// Array push method
var _push = Array.prototype.push;

// define your own push method
Array.prototype.push = function( item ) {

    // before Array push is called
    console.log( 'pushing ', item, ' into ', this );

    // call original Array push method
    _push.apply( this, arguments );

    // do whatever you like after
    // the push has been called
    if( this.length > 1000 ) {
        console.warn( 'potential memory leak going on here!!', this );
    }
}