在Javascript中，为什么要返回； 什么时候什么都不返回？

Question

I thought, if return nothing in a function, then the function returns null itself.

but sometimes, I can see like this code,

function test() {
  // do something
  return;
}

var test = function() { 
  // do something
  return;

}

is the return; is necessary? then why?

Answer 1

• return; does not return null but undefined

• When you see return; in a code, it's to stop the execution of the function before reaching its end. For example:

   function test(a) { if (a === 0) return; console.log(a); }

Here if the value of a is 0 , the console will not log. In other words, test will log anything given to it except the number 0.