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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