Array of functions in JavaScript

Last Updated : 20 Jun, 2019

Given an array containing functions and the task is to access its element in different ways using JavaScript.

Approach:

Declare an array of functions.
The array of function works with indexes like an array function.

Example 1: In this example, the function call is initiated from the element of array but the function is defined somewhere else. We can pass arguments to the function while calling.

<!DOCTYPE HTML>  
<html>  
    <head>  
        <title>  
            Array of functions in javascript 
        </title> 
    </head>  
      
    <body style = "text-align:center;">  
          
        <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 up = document.getElementById('GFG_UP'); 
            var down = document.getElementById('GFG_DOWN'); 
              
            function firstFun(str) { 
                down.innerHTML = str; 
            } 
            function secondFun(str) { 
                down.innerHTML = str; 
            } 
            function thirdFun(str) { 
                down.innerHTML = str; 
            } 
              
            // Declare array of functions 
            var arrayOfFunction = [ 
                firstFun, 
                secondFun, 
                thirdFun      
            ] 
              
            up.innerHTML = "Calling function from the array of functions"; 
              
            // Function call 
            function GFG_Fun() { 
                arrayOfFunction[0]("This is first function"); 
            } 
        </script>  
    </body>  
</html>                     

Output:

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

Example 2: In this example, the function (anonymous) itself is defined as the elements of array. We can access it by accessing the element of array followed by ().

<!DOCTYPE HTML>  
<html>  
    <head>  
        <title>  
            Array of functions in JavaScript 
        </title> 
    </head>  
      
    <body style = "text-align:center;">  
          
        <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 up = document.getElementById('GFG_UP'); 
            var down = document.getElementById('GFG_DOWN'); 
              
            // Declare an array of functions 
            var arrayOfFunction = [ 
                function() { 
                    down.innerHTML = "Inside First function"; 
                }, 
                  
                function() { 
                    down.innerHTML = "Inside Second function"; 
                }, 
                  
                function() { 
                    down.innerHTML = "Inside Third function"; 
                }      
            ] 
              
            up.innerHTML = "Calling function from the array of functions"; 
              
            function GFG_Fun() { 
                arrayOfFunction[2](); 
            } 
        </script>  
    </body>  
</html>                     

Output:

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

My Personal Notes

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