javascript if exist in array code example

Example 1: javascript array contains

var colors = ["red", "blue", "green"];
var hasRed = colors.includes("red"); //true
var hasYellow = colors.includes("yellow"); //false

Example 2: 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 3: 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