How do I check if an array includes a value in JavaScript

The includes() method determines whether a javascript array contains a specified element.

This method returns true if the array contains the element, and false if element not exist in array.

var list = ["A", "B", "C", "D", "E"];

console.log(list.includes("A")); // true

 console.log(list.includes("A",1)); //returns false, as "A" is not present at index 1. 

console.log(list.includes("B",1)); //returns True , as "B" is present at index 1. 

console.log(list.indexOf("A") !== -1 ); // true

Array indexOf function

how to check exact position of element using indexOf JS method

indexOf(element) method, which search for element in the specified array and returns the index of its first occurrence, and -1 if the array does not contain element

var JSArr = ["A", "B", "C", "D"];

console.log(JSArr.indexOf("A")) // 0  found at postion 0 
console.log(JSArr.indexOf("B")) // 1  found at postion 1 
console.log(JSArr.indexOf("F")) // -1  not found

Example 2 using function

      var JSArr = ["A", "B", "C", "D"];

      if (JSArr.indexOf("A") !== -1) {
        alert("Value exists");
      } else {
        alert("Value does not exists");
      }