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Welcome to the Javascript-higher-order-functions- wiki!

Higherorder functions in Javascript are known as callback functions. They are functions which are used as an argument in another function or return a function as a result. An simple example could be as follows:

function mainFunction(a, b, callback)
{
    var result = callback(a, b);
	
    return result; 
}

function callbackFunction(x, y)
{
   return x * y;
}

//Call
console.log(mainFunction(2, 2, callbackFunction));//Outputs 4

One thing which is important to understand is that callbackFunction could be defined differently (e.g. return x + y) and it will still work fine. Following this insight, High-order functions gives the developer a certain flexibility to change or write callback functions as they need it whithin a specific frame.

Another way is to write a callback function as an anonymous function, like this:

function mainFunction(a, b, callback)
{
    var result = callback(a, b);
	
    return result; 
}

//a = 2 and b = 2
var output = mainFunction
(
	2,
	2,
	function(x,y)
	{
		return x * y;
	}

)

console.log(output)//Outputs 4

The anonymous version could be often seen in jQuery.

Javascript offers already useful Higher-order functions. The following listed are used in this project:

1. forEach()
2. map()
3. filter()
4. reduce()
5. reduceRight()
6. sort()

STILL IN WORK!