How to get the index of the function in an array of functions which executed the fastest in JavaScript ?

In this example, we will learn how to get the index of the function in an array of functions that is executed the fastest in JavaScript.

Example:

Input: fun[] = [ hello, hello1, hello2 ]
Output: index of fastest is 0.

Explanation: Function hello execute fastest in all functions.

Input: fun[] = [ while1, while2, while3 ]
Output: index of fastest function is 2 

Approach: The below steps have to be followed to solve the problem:

• We will first Iterate over the given array.
• We will find the time taken by each function and store it in a different array with the same index value as the function index. The time taken can be found by getting the difference in time using the performance.now() method.
• Finally, we print the minimum index by getting the minimum value of the array using the Math.min() method.

Example 1: In this example, we will calculate the time taken by each function to execute. We will then print the index of the fastest function. using the above-mentioned approach

Javascript

<script>
    // 1st function
    function hello() {
      var s = "";
      var ans = ["The", " hello function ", "takes "];
      for (var i = 0; i < 3; i++) s += ans[i];
      console.log(s);
    }

    // 2nd function
    function hello1() {
      var s = "";
      var ans = ["The hello1 function", " takes "];
      for (var i = 0; i < 2; i++) s += ans[i];
      console.log(s);
    }

    // 3rd function
    function hello2() {
      var ans = "The hello2 function takes ";
      for (var i = 0; i < 1; i++) console.log(ans);
    }

    // Function to check time required by each function
    function findTime(f) {

      // Storing initial time in start
      var start = performance.now();

      // Calling the function
      f();

      // Storing time after running the function
      var end = performance.now();

      // Return time taken by function
      return end - start;
    }

    function findMinTime() {

      // Initializing array of functions
      var fun = [hello, hello1, hello2];

      // Initialising array of time taken by function
      var ans = [];

      // Iterating over all the functions and
      // storing time taken by them
      for (var i = 0; i < 3; i++) {
        var n = findTime(fun[i]);
        ans[i] = n;
        console.log(ans[i]);
      }

      // Finding the minimum time in array
      var answer = Math.min.apply(null, ans);
      c = ans.indexOf(answer);

      // Return index of fastest array
      return c;
    }

    var minTime = findMinTime();
    console.log("Index of fastest function:", minTime);
</script>

Output:

"The hello function takes "
0.10000000009313226
"The hello1 function takes "
0
"The hello2 function takes "
0
"Index of fastest function:"
1

Example 2: In this example, we will calculate the time taken by functions to perform some mathematical operations. We will then print the index of the fastest function.

Javascript

<script>
    // 1st function
    function fac(n) {
        let fact = 1;
        for (let i = 1; i <= 4; i++)
        fact *= i;
        console.log("Factorial of 4 is:", fact);
    }

    // 2nd function
    function fibo() {
        let fab = 0;
        let j = 1;
        for (let i = 2; i <= 6; i++) {
        let temp = fab;
        fab += j;
        j = temp;
        }
        console.log("6th fibonacci no is:", fab);
    }

    // 3rd function
    function binpow() {
        let j = 2;
        let k = 22;
        for (let i = 0; i < k; i++)
        j = ((j * j) % 1e9) + 7;
        console.log(
        "Power 2 to 22 mod 1e9+7 is:", j
        );
    }

    // Function to check time required
    // by each function
    function findTime(f) {

        // Storing initial time in start
        var start = performance.now();

        // Calling the function
        f();

        // Storing time after running the function
        var end = performance.now();

        // Return time taken by function
        return end - start;
    }

    function findMinTime() {

        // Initializing array of functions
        var fun = [fac, fibo, binpow];

        // Initialising array of time
        // taken by function
        var ans = [];

        // Iterating over all the functions
        // and storing time taken by them
        for (var i = 0; i < 3; i++) {
        var n = findTime(fun[i]);
        ans[i] = n;
        console.log(ans[i]);
        }

        // Finding the minimum time in array
        var answer = Math.min.apply(null, ans);
        c = ans.indexOf(answer);

        // Return index of fastest array
        return c;
    }

    var minTime = findMinTime();
    console.log("Index of fastest function:",
                minTime);
</script>

Output:

Factorial of 4 is: 24
0.30000001192092896
6th fibonacci no is: 5
0.20000001788139343
Power 2 to 22 mod 1e9+7 is: 221047735
0.30000001192092896
Index of fastest function: 1