Menu
×
   ❮     
HTML CSS JAVASCRIPT SQL PYTHON JAVA PHP HOW TO W3.CSS C C++ C# BOOTSTRAP REACT MYSQL JQUERY EXCEL XML DJANGO NUMPY PANDAS NODEJS R TYPESCRIPT ANGULAR GIT POSTGRESQL MONGODB ASP AI GO KOTLIN SASS VUE DSA GEN AI SCIPY AWS CYBERSECURITY DATA SCIENCE
     ❯   

JS Tutorial

JS HOME JS Introduction JS Where To JS Output JS Statements JS Syntax JS Comments JS Variables JS Let JS Const JS Operators JS Arithmetic JS Assignment JS Data Types JS Functions JS Objects JS Events JS Strings JS String Methods JS String Search JS String Templates JS Numbers JS BigInt JS Number Methods JS Number Properties JS Arrays JS Array Methods JS Array Search JS Array Sort JS Array Iteration JS Array Const JS Dates JS Date Formats JS Date Get Methods JS Date Set Methods JS Math JS Random JS Booleans JS Comparisons JS If Else JS Switch JS Loop For JS Loop For In JS Loop For Of JS Loop While JS Break JS Iterables JS Sets JS Maps JS Typeof JS Type Conversion JS Bitwise JS RegExp JS Precedence JS Errors JS Scope JS Hoisting JS Strict Mode JS this Keyword JS Arrow Function JS Classes JS Modules JS JSON JS Debugging JS Style Guide JS Best Practices JS Mistakes JS Performance JS Reserved Words

JS Versions

JS Versions JS 2009 (ES5) JS 2015 (ES6) JS 2016 JS 2017 JS 2018 JS 2019 JS 2020 JS 2021 JS 2022 JS 2023 JS IE / Edge JS History

JS Objects

Object Definitions Object Properties Object Methods Object Display Object Accessors Object Constructors Object Prototypes Object Iterables Object Sets Object Maps Object Reference

JS Functions

Function Definitions Function Parameters Function Invocation Function Call Function Apply Function Bind Function Closures

JS Classes

Class Intro Class Inheritance Class Static

JS Async

JS Callbacks JS Asynchronous JS Promises JS Async/Await

JS HTML DOM

DOM Intro DOM Methods DOM Document DOM Elements DOM HTML DOM Forms DOM CSS DOM Animations DOM Events DOM Event Listener DOM Navigation DOM Nodes DOM Collections DOM Node Lists

JS Browser BOM

JS Window JS Screen JS Location JS History JS Navigator JS Popup Alert JS Timing JS Cookies

JS Web APIs

Web API Intro Web Forms API Web History API Web Storage API Web Worker API Web Fetch API Web Geolocation API

JS AJAX

AJAX Intro AJAX XMLHttp AJAX Request AJAX Response AJAX XML File AJAX PHP AJAX ASP AJAX Database AJAX Applications AJAX Examples

JS JSON

JSON Intro JSON Syntax JSON vs XML JSON Data Types JSON Parse JSON Stringify JSON Objects JSON Arrays JSON Server JSON PHP JSON HTML JSON JSONP

JS vs jQuery

jQuery Selectors jQuery HTML jQuery CSS jQuery DOM

JS Graphics

JS Graphics JS Canvas JS Plotly JS Chart.js JS Google Chart JS D3.js

JS Examples

JS Examples JS HTML DOM JS HTML Input JS HTML Objects JS HTML Events JS Browser JS Editor JS Exercises JS Quiz JS Website JS Bootcamp JS Certificate

JS References

JavaScript Objects HTML DOM Objects


JavaScript Array Search


JavaScript Array indexOf()

The indexOf() method searches an array for an element value and returns its position.

Note: The first item has position 0, the second item has position 1, and so on.

Example

Search an array for the item "Apple":

const fruits = ["Apple", "Orange", "Apple", "Mango"];
let position = fruits.indexOf("Apple") + 1;
Try it Yourself »

Syntax

array.indexOf(item, start)
item Required. The item to search for.
start Optional. Where to start the search. Negative values will start at the given position counting from the end, and search to the end.

Array.indexOf() returns -1 if the item is not found.

If the item is present more than once, it returns the position of the first occurrence.


JavaScript Array lastIndexOf()

Array.lastIndexOf() is the same as Array.indexOf(), but returns the position of the last occurrence of the specified element.

Example

Search an array for the item "Apple":

const fruits = ["Apple", "Orange", "Apple", "Mango"];
let position = fruits.lastIndexOf("Apple") + 1;
Try it Yourself »

Syntax

array.lastIndexOf(item, start)
item Required. The item to search for
start Optional. Where to start the search. Negative values will start at the given position counting from the end, and search to the beginning

JavaScript Array includes()

ECMAScript 2016 introduced Array.includes() to arrays. This allows us to check if an element is present in an array (including NaN, unlike indexOf).

Example

const fruits = ["Banana", "Orange", "Apple", "Mango"];

fruits.includes("Mango"); // is true
Try it Yourself »

Syntax

array.includes(search-item)

Array.includes() allows to check for NaN values. Unlike Array.indexOf().

Browser Support

includes() is an ECMAScript 2016 feature.

ES 2016 is fully supported in all modern browsers since March 2017:

Chrome 52 Edge 15 Firefox 52 Safari 10.1 Opera 39
Jul 2016 Apr 2017 Mar 2017 May 2017 Aug 2016

includes() is not supported in Internet Explorer.



JavaScript Array find()

The find() method returns the value of the first array element that passes a test function.

This example finds (returns the value of) the first element that is larger than 18:

Example

const numbers = [4, 9, 16, 25, 29];
let first = numbers.find(myFunction);

function myFunction(value, index, array) {
  return value > 18;
}
Try it Yourself »

Note that the function takes 3 arguments:

  • The item value
  • The item index
  • The array itself

Browser Support

find() is an ES6 feature (JavaScript 2015).

ES6 is fully supported in all modern browsers since June 2017:

Chrome 51 Edge 15 Firefox 54 Safari 10 Opera 38
May 2016 Apr 2017 Jun 2017 Sep 2016 Jun 2016

find() is not supported in Internet Explorer.


JavaScript Array findIndex()

The findIndex() method returns the index of the first array element that passes a test function.

This example finds the index of the first element that is larger than 18:

Example

const numbers = [4, 9, 16, 25, 29];
let first = numbers.findIndex(myFunction);

function myFunction(value, index, array) {
  return value > 18;
}
Try it Yourself »

Note that the function takes 3 arguments:

  • The item value
  • The item index
  • The array itself

Browser Support

findIndex() is an ES6 feature (JavaScript 2015).

ES6 is fully supported in all modern browsers since June 2017:

Chrome 51 Edge 15 Firefox 54 Safari 10 Opera 38
May 2016 Apr 2017 Jun 2017 Sep 2016 Jun 2016

findIndex() is not supported in Internet Explorer.


JavaScript Array findLast() Method

ES2023 added the findLast() method that will start from the end of an array and return the value of the first element that satisfies a condition.

Example

const temp = [27, 28, 30, 40, 42, 35, 30];
let high = temp.findLast(x => x > 40);
Try it Yourself »

Browser Support

findLast() is an ES2023 feature.

It is supported in all modern browsers since July 2023:

Chrome 110 Edge 110 Firefox 115 Safari 16.4 Opera 96
Feb 2023 Feb 2023 Jul 2023 Mar 2023 May 2023

JavaScript Array findLastIndex() Method

The findLastIndex() method finds the index of the last element that satisfies a condition.

Example

const temp = [27, 28, 30, 40, 42, 35, 30];
let pos = temp.findLastIndex(x => x > 40);
Try it Yourself »

Browser Support

findLastIndex() is an ES2023 feature.

It is supported in all modern browsers since July 2023:

Chrome 110 Edge 110 Firefox 115 Safari 16.4 Opera 96
Feb 2023 Feb 2023 Jul 2023 Mar 2023 May 2023

Complete Array Reference

For a complete Array reference, go to our:

Complete JavaScript Array Reference.

The reference contains descriptions and examples of all Array properties and methods.