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JavaScript - TypedArray subarray() Method

The JavaScript TypedArray subarray() method is used to retrieve a sub-part of this typed array. It does not modify the original typed array but returns a new typed array object. It accepts two parameters that specify the position (index) of elements in the typed array.

Syntax

Following is the syntax of JavaScript TypedArray subarray() method −

subarray(begin, end)

Parameters

This method accepts two optional parameters named 'begin' and 'end', which are described below −

  • begin − It is the starting position from which the element at begin.

  • end − It is the end position at which the element at end(not included).

Return value

This method returns a new typed array object.

Examples

Example 1

If you omit both the 'begin' and 'end' parameters, this method returns a new typed array object that includes all the elements of the original typed array. So, if you don’t specify any range, it essentially creates a copy of the entire array.

In the following program, we are using the JavaScript TypedArray subarray() method to retrieve a sub-part of this typed array [1, 2, 3, 4, 5].

<html>
<head>
   <title>JavaScript TypedArray subarray() Method</title>
</head>
<body>
   <script>
      const T_array = new Uint8Array([1, 2, 3, 4, 5]);
      document.write("Original typed array: ", T_array);
      let new_t_array = new Uint8Array([]);
      new_t_array = T_array.subarray();
      document.write("<br>New typed array: ", new_t_array);
   </script>    
</body>
</html>

Output

The above program returns a new typed array as: [1, 2, 3, 4, 5].

Original typed array: 1,2,3,4,5
New typed array: 1,2,3,4,5

Example 2

If we omit the end parameter and pass only the 'begin' parameter, this method returns a new typed array that starts with the specified begin position till the last element.

In this example, we are using the subarray() method on a typed array to retrieve a sub-part of this typed array [10, 20, 30, 40, 50, 60, 70, 80]. The subarray starts from the specified starting position 2.

<html>
<head>
   <title>JavaScript TypedArray subarray() Method</title>
</head>
<body>
   <script>
      const T_array = new Uint8Array([10, 20, 30, 40, 50, 60, 70, 80]);
      document.write("Original typed array: ", T_array);
      const begin = 2;
      document.write("<br>Begin at: ", begin);
      let new_t_array = new Uint8Array([]);
      new_t_array = T_array.subarray(begin);
      document.write("<br>New typed array: ", new_t_array);
   </script>    
</body>
</html>

Output

After executing the above program, it will return a new typed array as: [30, 40, 50, 60, 70, 80].

Original typed array: 10,20,30,40,50,60,70,80
Begin at: 2
New typed array: 30,40,50,60,70,80

Example 3

If we pass both the 'begin' and 'end' parameters to this method, it returns a new typed array that starts with the specified begin position and extends up to, but excludes the end position.

In the following program, we are using the subarray() method on a typed array to retrieve a sub-part of this typed array [2, 4, 6, 8, 10, 12, 14, 16, 18, 20], starting from position 4, and ending just before position 8.

<html>
<head>
   <title>JavaScript TypedArray subarray() Method</title>
</head>
<body>
   <script>
      const even_t_array = new Uint8Array([2, 4, 6, 8, 10, 12, 14, 16, 18, 20]);
      document.write("Original typed array: ", even_t_array);
      const begin = 4;
      const end = 8;
      document.write("<br>Begin at: ", begin);
      document.write("<br>End at: ", end);
      let new_t_array = new Uint8Array([]);
      new_t_array = even_t_array.subarray(begin, end);
      document.write("<br>New typed array: ", new_t_array);
   </script>    
</body>
</html>

Output

Once the above program is executed, it returns a new typed array as −

Original typed array: 2,4,6,8,10,12,14,16,18,20
Begin at: 4
End at: 8
New typed array: 10,12,14,16
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