JavaScript Nested functions

Here the task is to create nested functions, JavaScript support nested functions. In the examples given below the output returning is a combination of the output from the outer as well as the inner function(nested function). 

Approach:

• Write one function inside another function.
• Make a call to the inner function in the return statement of the outer function.
• Call it fun(a)(b) where a is a parameter to the outer and b is to the inner function.
• Finally, return the combined output from the nested function.

Example 1: This example uses the approach discussed above. 

Javascript

function fun1(a) {
    function fun2(b) {
        return a + b;
    }
    return fun2;
}
function GFG_Fun() {
    console.log(fun1("A Online Computer Science Portal")
        (" GeeksforGeeks"));
}
GFG_Fun()

Output

A Online Computer Science Portal GeeksforGeeks

Example 2: This example uses the approach discussed above, but here the nested function is created differently than the previous one. 

Javascript

function fun1(a) {
    fun = function fun2(b) {
        return a + b;
    }
    return fun;
}
function GFG_Fun() {
    console.log(fun1("This is ")("GeeksforGeeks"));
}
GFG_Fun()

Output

This is GeeksforGeeks

JavaScript is best known for web page development but it is also used in a variety of non-browser environments. You can learn JavaScript from the ground up by following this JavaScript Tutorial and JavaScript Examples.

Supported Browser: 

• Google Chrome
• Edge
• Firefox
• Opera
• Safari