JavaScript Array fill() Method

Below is the example of the Array fill() method to fill with a single digit.

  • Example:
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    <script>
        // JavaScript code for fill() method
        function func() {
            var arr = [1, 23, 46, 58];
      
            // fill array with 87
            arr.fill(87);
            document.write(arr);
        }
        func();
    </script>

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  • Output:
    [87, 87, 87, 87]

The arr.fill() method is used to fill the array with a given static value. The value can be used to fill the entire array or it can be used to fill a part of the array.
Syntax:

arr.fill(value, start, end)

Parameters: This method accepts three parameters as mentioned above and described below:

  • value: It defines the static value with which the array elements are to be replaced.
  • start (Optional): It defines the starting index from where the array is to be filled with the static value. If this value is not defined the starting index is taken as 0. If start is negative then the net start index is length+start.
  • end (Optional): This argument defines the last index up to which the array is to be filled with the static value. If this value is not defined then by default the last index of the i.e arr.length – 1 is taken as the end value. If the end is negative, then the net end is defined as length+end.

Return value: This method does not return a new array. Instead of it modifies the array on which this method is applied.

Below examples illustrate the Array fill() method in JavaScript:



  • Example 1: In this example the method fill() fills the entire array with 87, replacing all the initial values present in the array.
    var arr = [1, 23, 46, 58];
    arr.fill(87); 
    

    Output:

    [87, 87, 87, 87]
  • Example 2: In this example the method fill() fills the array from index 1 to 2 one less than the upper index with 87, replacing all the initial values present in the array.
    var arr = [1, 23, 46, 58];
    arr.fill(87, 1, 3); 
    

    Output:

    [1, 87, 87, 58]
  • Example 3: In this example the method fill() fills the array from index 1 to 3 with 87, replacing all the initial values present in the array.
    var arr = [1, 23, 46, 58];
    arr.fill(87, 2); 
    

    Output:

    [1, 23, 87, 87]

Codes for the above method are defined as follows:

Program 1:

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<script>
    // JavaScript code for fill() method
    function func() {
        var arr = [1, 23, 46, 58];
  
        // Here value = 87, start index=1
        arr.fill(87, 2);
        document.write(arr);
    }
  
    func();
</script>

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Output:

[1, 23, 87, 87]

Program 2:

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code

<script>
    // JavaScript code for fill() method
    function func() {
        var arr = [1, 23, 46, 58];
  
        // here value = 87, start index=1 and
        // and last index = 3
        arr.fill(87, 1, 3);
        document.write(arr);
    }
  
    func();
</script>

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Output:

[1, 87, 87, 58]

Supported Browsers: The browsers supported by JavaScript Array fill() method are listed below:

  • Google Chrome 45.0
  • Micosoft Edge 12.0
  • Mozilla Firefox 31.0
  • Safari 7.1
  • Opera 32.0

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Improved By : nidhi_biet, Akanksha_Rai