Higher-Order Function in JavaScript

In this article we will have a look at Higher-Order functions in JavaScript. 

Before reading this article, you may want to go through the following articles:

• Invocation Patterns in JavaScript
• What is Call() Method in JavaScript
• What is Bind Method in JavaScript
• Objects in JavaScript
• Optional Parameter in JavaScript Function

Higher-Order function can be defined as follows:

1. It uses one or more functions as parameters
2. It returns a new function as a parameter

Let us say you have a function as follows:

function FindGreater(a, b)
{

    if (a > b)
        return a;

    else
        return b;

}

You will pass this function as an argument to another function. That function will be called a Higher-Order function.

Assume we have created another function with the name IamHigherOrderFunction.

function IamHighorderFunction(functionargument)
{
    return function ()
    {
        var result = functionargument.apply(this, arguments);
        turn "I am returned from high function" + result;
    }
}

Some important points about the function above are:

1. It takes a function as an argument
2. It returns a function as output

In the function we are just appending a text to the result of the passed function as an argument. You can call a higher-order function as follows:

var result  = IamHighorderFunction(FindGreater);           
alert(result(9,5));

You will get output as in the following. We are passing the FindGreater function as an argument to the Higher-order function named IamHigherorderFunction.



You will find use of Higher-Order functions very often in JavaScript. I hope you find this article useful. Thanks for reading.