How to Check If a Value Exists in an Array in JavaScript

Topic: JavaScript / jQueryPrev|Next

Answer: Use the indexOf() Method

You can use the indexOf() method to check whether a given value or element exists in an array or not. The indexOf() method returns the index of the element inside the array if it is found, and returns -1 if it not found. Let's take a look at the following example:

  • <script>    
  •     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!")
  •     }
  • </script>

ES6 has introduced the includes() method to perform this task very easily. But, this method returns only true or false instead of index number, as you can see here:

  • <script>    
  •     var fruits = ["Apple", "Banana", "Mango", "Orange", "Papaya"];
  •     alert(fruits.includes("Banana")); // Outputs: true
  •     alert(fruits.includes("Coconut")); // Outputs: false
  •     alert(fruits.includes("Orange")); // Outputs: true
  •     alert(fruits.includes("Cherry")); // Outputs: false
  • </script>

All modern browsers supports the includes() method and it is preferred for modern applications.

Please check out the tutorial on JavaScript Arrays to learn more about the arrays.

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