Recursion for Coding Interviews in JavaScript/

...

/

Count all Occurrences of a Number

Count all Occurrences of a Number

In this lesson, we will learn how to count all occurrences of a key in a given array.

We'll cover the following...

What does “Count all Occurrences of a Number” mean?

Our task is to find the number of times a key occurs in an array.

For example:

Number of occurrences of a key.
Number of occurrences of a key.

Implementation

Press + to interact
function count(myArray, key) {
  // Base case
  if (myArray.length == 0) {
    return 0;
  }
  // Recursive case1
  if (myArray[0] == key) {
    return 1 + count(myArray.slice(1), key);
  }
  // Recursive case2
  else {
    return 0 + count(myArray.slice(1), key);
  }
}
// Driver Code
myArray = [1, 2, 1, 4, 5, 1];
key  = 1;
console.log(count(myArray, key));

Explanation

We need to count the number of times key occurs in an array. ...