JavaScript includes() method; In this tutorial, i am going to show you how to checks whether the javascript array contains the specified element or not using the includes() method on the array instance.
How to Check if an Array Contains a Value in JavaScript
Using the javaScript includes()
method, you can if an array contains value or not.
The javaScript includes method returns true
if an array contains a given element; Otherwise, it returns false
.
Syntax of javaScript includes() method
The following illustrates the syntax of the includes()
method:
array.includes(element,fromIndex);
Code language: CSS (css)
The includes()
accepts two arguments:
- The first argument is the
element
that can be searched. - The
fromIndex
is the position in the array to which the search starts.
Example 1 – To Check if an Array Contains a Value in JavaScript
Here, i will take an example for check if an array contains a value in javascript; as shown below:
See the following example:
[1,2,3].includes(2); // true [1,2,3].includes(4); // false [1,2,3].includes(1,1); // false
Both methods indexOf()
method and the includes()
method works absolutely fine with the NaN
:
[NaN].includes(NaN); // true
Note that the includes()
doesn’t differentiate between +0
and -0
. See the following example:
[-0].includes(+0); // true
The following example demonstrates how to use the includes()
method to check if an object is in an array.
let php = {name: 'PHP' }, java = { name: 'JAVA'}, c = {name: 'C'} let lang = [java, c]; console.log(lang.includes(java)); // true console.log(lang.includes(php)); // false
In this example:
- First, we initialized the
lang
array with three objects:java
andc
. - Then, we used the
includes()
method to check if thelang
array contains thejava
object, in this case, it returns true. - Finally, the
php
object is not in thelang
array, therefore, theincludes()
method returnstrue
as expected.
Examples 2 – To Check if an Array Contains a Value in using Javascript IndexOf()
Here, i will take an example for check if the array contains an element. As shown below:
let numbers = [3,4,5,6,7,8]; if(numbers.indexOf(5) !== -1){ // process here
Conclusion
In this tutorial, you have learned how to use the JavaScript Array includes()
method to determines whether an array contains a specified element.
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