JavaScript | Array map() Method
The map() method in JavaScript creates an array by calling a specific function on each element present in the parent array. It is a non-mutating method. Generally map() method is used to iterate over an array and calling function on every element of array.
Syntax:
array.map(function(currentValue, index, arr), thisValue)
Parameters: This method accepts two parameters as mentioned above and described below:
- function(currentValue, index, arr): It is required parameter and it runs on each element of array. It contains three parameters which are listed below:
- currentValue: It is required parameter and it holds the value of current element.
- index: It is optional parameter and it holds the index of current element.
- arr: It is optional parameter and it holds the array.
- thisValue: It is optional parameter and used to hold the value of passed to the function.
Return Value: It returns a new array and elements of arrays are result of callback function.
Below examples illustrate the use of array map() method in JavaScript:
Example 1: This example use array map() method and return the square of array element.
<!DOCTYPE html> <html> <head> <title> JavaScript Array map() Method </title> </head> <body> <div id="root"></div> <!-- Script to use Array map() Method --> <script> var el = document.getElementById('root'); var arr = [2, 5, 6, 3, 8, 9]; var newArr = arr.map(function(val, index){ return {key:index, value:val*val}; }) console.log(newArr) el.innerHTML = JSON.stringify(newArr); </script> </body> </html> |
chevron_right
filter_none
Output:
Example 2: This example use array map() method to concatenate character ‘A’ with every character of name.
<!DOCTYPE html> <html> <head> <title> JavaScript Array map() Method </title> </head> <body> <div id="root"></div> <script> var el = document.getElementById('root'); var name = "Pankaj"; // New array of character and names // concatenated with 'A' var newName = Array.prototype.map.call(name, function(item) { return item + 'A'; }) console.log(newName) </script> </body> </html> |
chevron_right
filter_none
Output:
Example 3: This example use array map() method to return the square of array elements.
<!DOCTYPE html> <html> <head> <title> JavaScript Array map() Method </title> </head> <body> <div id="root"></div> <script> var el = document.getElementById('root'); // Map is being called directly on an array // Arrow function is used el.innerHTML = [6, 7, 4, 5].map((val)=>{ return val*val; }) </script> </body> </html> |
chevron_right
filter_none
Output:
36, 49, 16, 25
Recommended Posts:
- JavaScript | Array from() Method
- JavaScript | Array.from() method
- JavaScript | Array.findIndex() Method
- JavaScript | Array.splice() Method
- JavaScript | Array valueOf() Method
- JavaScript | array.entries() Method
- JavaScript | Array.fill() Method
- JavaScript | Array.join() Method
- JavaScript | Array reduce() Method
- JavaScript | Array.find() Method
- indexOf method in an object array in JavaScript
- How to get the elements of one array which are not present in another array using JavaScript?
- RMS Value Of Array in JavaScript
- JavaScript | Array pop()
- How to convert Set to Array in JavaScript?
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
