Is This Possible?

[Niccaman]

Lets say I have:

 

function example(){
  // code 1
}

 

...already declared in the document. Now i need to insert some new code as an extension of the 'example()' so that it will run example() and then my newer code.

 

 

For example, I know this isnt possible, but I wanna do this:

 

example.extend(function(){
  // code 2
});

 

... so that when I call 'example()' later, it will run both code 1 AND code 2.

[.josh]

<script type='text/javascript'>

// original function
function someFunction () {
  document.write('original function<br/>');
}


// copy to something else
var original_someFunction = someFunction;

// new function: make it like this...
var someFunction = function() {
  // call original function
  original_someFunction();

  document.write('new function<br/>');
};

// example...
someFunction();


</script>

 

 

[Niccaman]

haha ofcourse! wp mate.

[goodacre.liam]

If you want to create new instances of functions which extend another, the following could help:

//@Using Function prototype
Function.prototype.extend = function (_callback) {
var self = this;
return function () {
	self();
	_callback();
};
}

//@Using Function - Preferred Method
Function.extend = function (_base, _callback) {
return function () {
	_base();
	_callback();
};
}


//@Example
var func1, func2, func3;

// Base function
func1 = function () {
console.log('FUNC1');
};

// Using prototype extend
func2 = func1.extend(function () {
console.log('FUNC2');
});

// Using Function extend - Preferred Method
func3 = Function.extend(func2, function () {
console.log('FUNC3');
});

 

I wouldn't use the Function.prototype method, as modifying core object prototypes is usually a bad idea.  But extending Function is perfectly fine.

In the examples above, func1 would log FUNC1, func2 would log FUNC1, FUNC2, and func3 would log FUNC1, FUNC2, and FUNC3.

 

 

If you want to attach methods automatically, for example:

func1.extend(function () {
  // extension code
})

 

And you want func1 to be modified, you could write a new function builder, which stores a chain of methods.  As such:

 

//@Method builder
var Method = function (_func) {
var chain = [_func];
var core = function () {
	for (var index = 0, max = chain.length; index < max; ++index) {
		chain[index]();
	}
};
core.extend = function (_func) {
	chain.push(_func);
};
return core;
};

//@Demo usage
var func1;
func1 = new Method(function () {
console.log('Running func1');
});
func1.extend(function () {
console.log('Extended');
});
func1.extend(function () {
console.log('And Again!');
});

func1(); // logs 'Running func1', 'Extended', and 'And Again!'

 

Hope this helps!