Right and wrong way to "Confirm the Ending"

JavaScript
#1

Apologize if this is in the wrong category. Was unsure if it fit under the help or javascript section. Appreciate anyone who replies.

The context:
So this is not so much a question for help as it is a question about function.
When finishing every task I usually take a look at the Get a Hint section to find out how the task was intended to be solved. The hint page says to use the str.slice() function, and my question is this:

  1. Are there any notible differences in efficiency between the slice() and substring() methods?
  2. Is there a right and wrong way to solve it?

My thought process and code is added below.

My code

function confirmEnding(str, target) {
  // since the target can be an arbritrary length we first need to find out how long the target is
  // then we need to find out how long the str is 
  // subtract the target length from the string length to find where the substring should start.
  // we must then compare the ending of the substring with the target and return true or false.

  return (str.substring((str.length-target.length)) === target);
}

confirmEnding("Bastian", "n");

Link to the challenge:
Confirm the Ending task
Hint Page for Confirm the Ending

#2

First I think the slice use for array and substring method use for string. So you should be used substring.

  1. Base on syntax substring: str.substring(indexStart[, indexEnd]).

If you have a string is: var str = ‘Mozilla’ (Length of the string is 7);

  • str.substring(0,3) => Method 1 will get string form indexOf 0 to indexOf 3 => Result is ‘Moz’

  • str.substring(5) => Method 2 will get string form indexOf 5 to indexOf 7(str.length) => Result is ‘la’

So if you want to find the string end:

  1. You find length of the target.

  2. Base on length of target you can you method 2 to find the indexOf start by (str.length-target.length)

  3. You have the substring of string

  4. Compare with target.

Example:
var str = ‘Mozilla’
confirmEnding(“Mozilla”, “a”);
Solution:
Length of string ‘Mozilla’ = 7 and length of ‘a’ = 1.
Next i want to get character end of the string with length = 1.
I get the character by str.substring(str.length - target.length) = str.substring(7 -1) = str.substring(6)
In the string get chracter from indexOf 6 -> end(indexOf7).
We has chracter a then we compare with target

#3

Thank you for the reply
I understood how it works, I was just not sure when it was apropriate to use slice() or substring().
You solved that as well.:smiley:

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#4