how to check whether an element is present in an array in javascript code example

Example 1: check if array does not contain value javascript

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

var n = fruits.includes("Mango"); // true

var n = fruits.includes("Django"); // false

Example 2: javascript method to see if item exists in array

var fruits = ["Apple", "Banana", "Mango", "Orange", "Papaya"];
    
    // Check if a value exists in the fruits array
    if(fruits.indexOf("Mango") !== -1){
        alert("Value exists!")
    } else{
        alert("Value does not exists!")
    }

Example 3: how to check if item is in list js

var myList=["a", "b", "c"];
mylist.includes("d")//returns true or false

Example 4: check value exist in array javascript

[1, 2, 3].includes(2);     // true
[1, 2, 3].includes(4);     // false
[1, 2, 3].includes(1, 2);  // false (second parameter is the index position in this array at which to begin searching)

Example 5: javascript check if in array

var extensions = ["image/jpeg","image/png","image/gif"];          
if(extensions.indexOf("myfiletype") === -1){
	alert("Image must be .png, .jpg or .gif");
}

Example 6: how to Check if an array contains a string

// To check if an array contains a string 

const colors = ['red', 'green', 'blue'];
const result = colors.includes('red');

console.log(result); // true

// Or 

const colors = ['Red', 'GREEN', 'Blue'];
const result = colors.map(e => e.toLocaleLowerCase())
                     .includes('green');                          

console.log(result); // true