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JavaScript - TypedArray find() Method

The JavaScript TypeArray find() method returns the value of the first element in the current typed array that satisfies the provided testing function. If no values are satisfied or no value is passed to the testing function, undefined is returned.

Here's the some additional points about find() method −

  • The find() method operates on a TypedArray (such as Uint8Array, Int16Array, etc.).

  • It accepts a testing function as a parameter.

  • The testing function is executed for each element in the TypedArray.

  • If an element satisfies the condition specified by the testing function (returns a true value), that element is returned as the result.

  • If no elements pass to the testing function, undefined is returned.

Syntax

Following is the syntax of JavaScript TypedArray find() method −

find(callbackFn, thisArg)

Parameters

This method accepts two parameters named 'callbackFn' and 'thisArg', which are described below −

callbackFn − This parameter is a testing function that will be executed for each element in the TypedArray.

This function takes three parameters named 'element', 'index', and 'array'. Here's the description for each parameter −

  • element − Represents the current element being processed in the TypedArray.

  • index − Indicates the index (position) of the current element within the TypedArray.

  • array − Refers to the entire TypedArray.

thisArg (optional) − This is an optional parameter that allows you to specify the value of this within the callbackFn.

Return value

This method returns the first element is TypedArray that satisfied the provided test function, 'undefined' otherwise.

Examples

Example 1

In the following example, we use the JavaScript TypedArray find() method to search for the first even number in the original TypedArray [1, 2, 3, 4, 5, 6, 7, 8]. We create a testing function named isEven() that checks if a number is even, and then pass this function as an argument to the find() method.

<html>
<head>
   <title>JavaScript TypedArray find() Method</title>
</head>
<body>
   <script>
      function isEven(element, index, array){
         return element %2 == 0;
      }
      const T_array = new Int8Array([1, 2, 3, 4, 5, 6, 7, 8]);
      document.write("Orizinal TypedArray: ", T_array);
      document.write("<br>First even number in TypedArray is: ");
      document.write(T_array.find(isEven));
   </script>    
</body>
</html>

Output

The above program returns the first even number as '2' in the TypedArray [1, 2, 3, ,4 ,5 ,6 ,7, 8]

Orizinal TypedArray: 1,2,3,4,5,6,7,8
First even number in TypedArray is: 2

Example 2

The following is another example of the JavaScript TypedArray find(). We use this method to search for the first negative number in this typed array [1, 2, -1, 0, 1, 2, -2, -3]. We create a testing function named isNegative() that checks if a number is negative and then pass this function as an argument to the find() method.

<html>
<head>
   <title>JavaScript TypedArray find() Method</title>
</head>
<body>
   <script>
      function isNegative(element, index, array){
         return element < 0;
      }
      const T_array = new Int8Array([1, 2, -1, 0, 1, 2, -2, -3]);
      document.write("Orizinal TypedArray: ", T_array);
      document.write("<br>First negative number in TypedArray is: ");
      document.write(T_array.find(isNegative));
   </script>    
</body>
</html>

Output

After executing the above program, it returns first negative number as -1 in the TypedArray [1, 2, -1, 0, 1, 2, -2, -3].

Orizinal TypedArray: 1,2,-1,0,1,2,-2,-3
First negative number in TypedArray is: -1

Example 3

If no value satisfies the testing function, it will return 'undefined'.

In this program, we create a function called isPrime() that checks whether a number is prime. We use this function as an argument to the find() function to retrieve the first prime number in the TypedArray [4, 6, 8, 9]. However, since no value satisfies the isPrime() function, the find() method returns undefined.

<html>
<head>
   <title>JavaScript TypedArray find() Method</title>
</head>
<body>
   <script>
      function isPrime(element, index, array){
         let begin = 2;
         while(begin <= Math.sqrt(element)){
            if(element % begin++ < 1){
               return false;
            }
         }
         return element > 1;
      }
      const T_array = new Int8Array([4, 6, 8, 9]);
      document.write("Orizinal TypedArray: ", T_array);
      document.write("<br>First negative number in TypedArray is: ");
      document.write(T_array.find(isPrime));
   </script>    
</body>
</html>

Output

Once the above program is executed, it will return 'undefined'.

Orizinal TypedArray: 4,6,8,9
First negative number in TypedArray is: undefined
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