我将如何简化这个严格的平等表达

Question

Is there any way to shorthand the if expression without introducing a new variable?

if ((c2 === 'RED') || (c2 === 'GREEN') || (c2 === 'BLUE')) {
 return true;
} else {
 return false
}

I figured it would be something like: if ((c2 === ('RED'|| 'GREEN' ||'BLUE')))

Answer 1

Array.indexOf does strict checking, so you could do

if ( ['RED','GREEN','BLUE'].indexOf(c2) !== -1 ) {...

and as it already returns a boolean, you could just return it directly without the condition

Answer 2

You can shorten it by taking advantage of the fact that the comparisons give you boolean results, so you don't need an explicit return with the boolean value:

return ((c2 === 'RED') || (c2 === 'GREEN') || (c2 === 'BLUE'));

You can also make an object:

var targets = { RED: 1, GREEN: 1, BLUE: 1 };
return !!targets[c2]; // !! turns the 1 into true

(You could use true in the object to avoid the !! .)