JavaScript返回this.key = variable;

Question

Sorry if this questions been asked I have been searching for the past couple of hours and I couldn't phrase what my sitution was in a question.

simply put I want my script to be as small as and with the specified method below can this be achieved without fault.

Basically if i have the below:

function myFunction(val){
   this.key = val;
}
myFunction.prototype.changeKey = function(newVal){
   this.key = newVal;
   return this.key; 
}

that's basically an over-simplification of my script.

But is it just as okay to do this.

myFunction.prototype.changeKey = function(newVal){
   return this.key = newVal; 
}

I am using google chrome it seems to works fine but are there any bugs/issues with this or is it 100% fine to do this. I have never come across it before!!

Answer 1

Assignment "returns" the assigned value, so it is absolutely okay to write the code you have.

Readability may suffer, however. This is the kind of step that should be taken by a minifier, not manually.

Answer 2

It's the same as

this.key = newVal;
return newVal;

because the expression a = b evaluates to the value of b , which is b .

It's similar to the idea behind

if(a++ < 10)

The value of a changes, but it also evaluates to a before the expression, so the side-effect is used.