How to call a function that return another function in JavaScript ?

The task is to call a function which returns another function with the help of JavaScript. we’re going to discuss few techniques.

Approach:

First call the first function-1.
Define a function-2 inside the function-1.
Return the call to the function-2 from the function-1.

Example 1: In this example, “from function 2” is returned from the fun2 which is finally returned by fun1.

<!DOCTYPE HTML> 
<html> 
  
<head> 
    <title> 
        JavaScript  
      | Function that return a function. 
    </title> 
</head> 
  
<body style="text-align:center;"
      id="body"> 
    <h1 style="color:green;">   
            GeeksForGeeks 
        </h1> 
    <p id="GFG_UP" 
       style="font-size: 19px; 
              font-weight: bold;"> 
    </p> 
    <button onclick="GFG_Fun()"> 
        click here 
    </button> 
    <p id="GFG_DOWN"
       style="color: green;  
              font-size: 24px; 
              font-weight: bold;"> 
    </p> 
    <script> 
        var el_up = document.getElementById("GFG_UP"); 
        var el_down = document.getElementById("GFG_DOWN"); 
        el_up.innerHTML =  
          "Click on the button to call a function, "+ 
          "which returns the call to another function."; 
  
        function fun1() { 
            function fun2() { 
                return "From function fun2"; 
            } 
            return fun2(); 
        } 
  
        function GFG_Fun() { 
            el_down.innerHTML = fun1(); 
        } 
    </script> 
</body> 
  
</html> 

Output:

Before clicking on the button:
After clicking on the button:

Example 2: In this example, “Alert from fun2” is returned from the fun2 alongwith an alert, Returned value finally returned by fun1.

<!DOCTYPE HTML> 
<html> 
  
<head> 
    <title> 
        JavaScript  
      | Function that return a function. 
    </title> 
</head> 
  
<body style="text-align:center;"
      id="body"> 
    <h1 style="color:green;">   
            GeeksForGeeks 
        </h1> 
    <p id="GFG_UP"
       style="font-size: 19px; 
              font-weight: bold;"> 
    </p> 
    <button onclick="GFG_Fun()"> 
        click here 
    </button> 
    <p id="GFG_DOWN" 
       style="color: green;  
              font-size: 24px;  
              font-weight: bold;"> 
    </p> 
    <script> 
        var el_up = document.getElementById("GFG_UP"); 
        var el_down = document.getElementById("GFG_DOWN"); 
        el_up.innerHTML =  
          "Click on the button to call a function, "+ 
          "which returns the call to another function."; 
  
        function fun1() { 
            function fun2() { 
                alert("From function fun2"); 
                return "Alert from fun2 "; 
            } 
            return fun2(); 
        } 
  
        function GFG_Fun() { 
            el_down.innerHTML = fun1(); 
        } 
    </script> 
</body> 
  
</html> 

Output:

Before clicking on the button:
After clicking on the button:

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