How to map Javascript array value

Description

map() accepts two arguments:

• a function to run on each item and
• an optional scope object

map() runs the given function on every item and returns the result of each function call in an array.

The function passed in receives three arguments:

• the array item value,
• the position of the item in the array
• the array object itself.

Example

The following code uses map() to double each value in array.

var numbers = [1,2,3,4,5,4,3,2,1]; 
        /*from www  .  j  a v  a  2  s  .co m*/
var mapResult = numbers.map(function(item, index, array){ 
   return item * 2; 
}); 
console.log(mapResult); 

The code above generates the following result.

map() does not change the values contained in the array.