Question

How to check whether an array includes a certain value in JavaScript

Answer 1

var arr = [1, 2, 3, 4, 5];
 
if (arr.includes(2))
    document.write("yes");
else
    document.write("no");
 
/*
run:  
 
yes 
 
*/

 

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Answer 2

var arr = [1, 2, 3, 4, 5];
 
if (arr.includes(7))
    document.write("yes");
else
    document.write("no");
 
/*
run:  
 
no  
 
*/

 

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Answer 3

// var boolean = array.includes(searchElement[, fromIndex])

var arr = [1, 2, 3, 4, 5];
 
if (arr.includes(4, 3))
    document.write("yes");
else
    document.write("no");
 
/*
run:  
 
yes   
 
*/

 

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Answer 4

// var boolean = array.includes(searchElement[, fromIndex])

var arr = [1, 2, 3, NaN, 5];
 
if (arr.includes(NaN))
    document.write("yes");
else
    document.write("no");
 
/*
run:  
 
yes   
 
*/

 

70+ SQL courses for beginners and professionals