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JavaScript - Array includes() Method

The JavaScript Array includes() method is used with the arrays to check if a particular element is present in the array. It returns a boolean value as a result: “true” if thr element is found in the array, and “false” if it is not present. This method is case sensitive for strings and checks for object references.

If we provide a negative "fromIndex" to this method, the search starts from backwards. For instance, -1 represents the last element.

Syntax

Following is the syntax of JavaScript Array includes() Method −

array.includes(searchElement, fromIndex);

Parameters

This method accepts two parameters. The same is described below.

  • searchElement − The element that you are searching for in the array.
  • fromIndex − The index in the array from which to start searching. If not specified, the search starts from the beginning of the array.

Return value

This method returns "true" if the search element is found in the array, else, "false".

Examples

Example 1

In the following example, we are using the JavaScript Array includes() method to search for the element "Dinosaur" in the specified array.

<html>
<body>
   <p id="demo"></p>
   <script>
      const animals = ["Lion", "Cheetah", "Tiger", "Elephant", "Dinosaur"]
      let result = animals.includes("Dinosaur");
      document.getElementById("demo").innerHTML = result;
   </script>
</body>
</html>

Output

After executing the program, the includes() method returns "true" as the element “Dinosaur” is present in the specified array.

true

Example 2

In the following example, we are searching for the element "Wolf" in the specified array −

<html>
<body>
   <p id="demo"></p>
   <script>
      const animals = ["Lion", "Cheetah", "Tiger", "Elephant", "Dinosaur"]
      let result = animals.includes("Wolf");
      document.getElementById("demo").innerHTML = result;
   </script>
</body>
</html>

Output

After executing the program, the includes() method returns "false" as the element "Dinosaur" is not present in the specified array.

false

Example 3

Here, we are checking if the specified array contains the element “Elephant”, starting from the index postion 2 −

<html>
<body>
   <p id="demo"></p>
   <script>
      const animals = ["Lion", "Cheetah", "Tiger", "Elephant", "Dinosaur"]
      let result = animals.includes("Elephant", 2);
      document.getElementById("demo").innerHTML = result;
   </script>
</body>
</html>

Output

The program returns “true” because the element "Elephant" is present after the index postion 2.

true

Example 4

Here, we are checking if the specified array contains the element "Cheetah", starting from the index postion 3 −

<html>
<body>
   <p id="demo"></p>
   <script>
      const animals = ["Lion", "Cheetah", "Tiger", "Elephant", "Dinosaur"]
      let result = animals.includes("Cheetah", 3);
      document.getElementById("demo").innerHTML = result;
   </script>
</body>
</html>

Output

The program returns "false" because the element "Cheetah" is present after the index postion 3.

false
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