Recursion in Javascript

A recursive function is the ability to call itself and stop on matching the criteria.

For example, we could write a recursion to reverse a string from "ABC" to "CBA".

// Parameter: A string.
// Return: Last character of the string.

function reverseString(p_val){

  // Get the string's length
  var length = p_val.length;

  // Get the last character
  var lastchar = p_val.charAt(length - 1);

  if (length == 1) {

     // Return the last char
     return lastchar;

  } else {

    // Run the recursion
    return lastchar + reverseString(p_val.substring(0,length - 1))

  }

}

Let's say the parameter is "ABC". The process will be:

1. Return: C + reverseString("AB") 
2. Return: C + B + reverseString("A") 
3. Return: C + B + A