TypeScript | Array map() Method

The Array.map() is an inbuilt TypeScript function that is used to create a new array with the results of calling a provided function on every element in this array.

Syntax:

array.map(callback[, thisObject])

Parameter: This method accepts two parameters as mentioned above and described below: 

• callback : This parameter is the function that produces an element of the new Array from an element of the current one.
• thisObject : This parameter is the Object to use as this when executing callback.

Return Value: This method returns the created array. 

Below examples illustrate the Array map() method in TypeScript.
Example 1:

JavaScript

// language is TypeScript

    // Driver code
    var arr = [ 11, 89, 23, 7, 98 ];

    // use of map() method
    var val = arr.map(Math.log)

    // printing element
    console.log( val );

Output:

[ 2.3978952727983707,
  4.48863636973214,
  3.1354942159291497,
  1.9459101490553132,
  4.584967478670572 ]

Example 2:

JavaScript

// language is TypeScript

    // Driver code
    var arr = [2, 5, 6, 3, 8, 9];

    // use of map() method

    var newArr = arr.map(function(val, index){

      // printing element
      console.log("key : ",index, "value : ",val*val);
    })

Output:

key :  0 value :  4
key :  1 value :  25
key :  2 value :  36
key :  3 value :  9
key :  4 value :  64
key :  5 value :  81

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