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JavaScript | typedArray.from() with Examples

  • Last Updated : 03 Aug, 2018

The typedArray.from() is an inbuilt function in JavaScript which is used to construct a new typedArray from a normal array or any iterable object.
List of different typedArrays are specified below-

  • Int8Array();
  • Uint8Array();
  • Uint8ClampedArray();
  • Int16Array();
  • Uint16Array();
  • Int32Array();
  • Uint32Array();
  • Float32Array();
  • Float64Array();

Syntax:

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typedArray.from(source, mapFn, thisArg)

Parameters: It accepts three parameters which are specified below-

  • source: It is a normal array or any iterable object for converting to a typedArray.
  • mapFn: It is optional and it is map function to call on every element of the typedArray.
  • thisArg: It is optional and it is the value to be used while executing mapFn function.

Return value: It returns a new typedArray instance.
JavaScript code to show the working of this function:
Code #1:






<script>
  
    // Constructing an iterable object
    var a = new Set([ 5, 10, 15, 20, 25 ]);
    var b = new Set([ 1, 2, 3, 4, 5 ]);
    var c = new Set([ 1, 3, 5, 7, 9 ]);
    var d = new Set([ 2, 4, 6, 8, 10 ]);
  
    // Calling from() function
    A = Uint8Array.from(a);
    B = Uint8Array.from(b);
    C = Uint8Array.from(c);
    D = Uint8Array.from(d);
  
   // Printing new typedArray instance
    document.write(A + "<br>");
    document.write(B + "<br>");
    document.write(C + "<br>");
    document.write(D);
  
</script>

Output:

5, 10, 15, 20, 25
1, 2, 3, 4, 5
1, 3, 5, 7, 9
2, 4, 6, 8, 10

Code #2:




<script>
  
    // Calling from() function
    A = Uint16Array.from('123456');
    B = Uint16Array.from('80397418327');
  
    // Printing new typedArray instance
    document.write(A + "<br>");
    document.write(B + "<br>");
  
</script>

Output:

1, 2, 3, 4, 5, 6
8, 0, 3, 9, 7, 4, 1, 8, 3, 2, 7

Code #3:




<script>
  
    // Constructing an iterable object
    var a = new Set([ 5, 10, 15, 20, 25 ]);
    var b = new Set([ 1, 2, 3, 4, 5 ]);
    var c = new Set([ 1, 3, 5, 7, 9 ]);
    var d = new Set([ 2, 4, 6, 8, 10 ]);
  
    // Calling from() function
    A = Uint8Array.from(a, x => x + 1);
    B = Uint8Array.from(b, x => x + 2);
    C = Uint8Array.from(c, x => x * 2);  
    D = Uint8Array.from(d);
  
    // Printing new typedArray instance
   document.write(A + "<br>");
   document.write(B + "<br>");
   document.write(C + "<br>");
   document.write(D);
  
</script>

Output:

6, 11, 16, 21, 26
3, 4, 5, 6, 7
2, 6, 10, 14, 18
2, 4, 6, 8, 10



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