Array mapping

In this chapter you will learn:

How to use array map() function

Array map() function

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.

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

<!DOCTYPE html><!--  j  a  va2s.c  o m-->
<html>
<head>
    <script type="text/javascript">
        var numbers = [1,2,3,4,5,4,3,2,1]; 
        
        var mapResult = numbers.map(function(item, index, array){ 
            return item * 2; 
        }); 
        document.writeln(mapResult); 
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

The code above generates the following result.

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

Next chapter...

What you will learn in the next chapter:

How to use Javascript array forEach function

Array mapping

Array map() function

Next chapter...

Array Type

Array creation

Array type detecting

Array iterate

Array Length

Add to Array

Array join

Array concat()

Array every method

Array search from start with indexOf()

Array search from the end with lastIndexOf()

Array filter

Array mapping

Array forEach

Array pop and push

Array shift()

Array reduce()

Array reduceRight()

Array reverse()

Array slice()

Array some()

Array splice()

Array sort()

Array toString()

Array unshift()