If you are a beginner in Javascript, understanding conditional statements is very important.
Why if conditional statements considered as one of the fundamental concepts of Javascript or any other programming language? It is mainly because if/else statements help in directing the flow of your code based on specific conditions.
It will provide the ability to dictate which code should run under certain circumstances.

Here are some site's where you can understand or learn more about conditional statements.

IT Beginner Series: JavaScript IF/ELSE Exercises

JavaScript conditional statements and loops - Exercises, Practice, Solution

If Else Statements