Why use "!!!"?

Question

following codes:

var a = {};
if(!!!a[tabType]){
   a[tabType] = [];
   a[tabType].push([self,boxObj]);
}else{
   a[tabType].push([self,boxObj]);
}

I think!!! [tabType] equals! a [tabType] why use "!!!" not "!"

Thank you!

+3

Koerr Jun 11 '10 at 4:15

3 answers

There is no point. This is exactly equivalent to use !.

+2

Tim down Jun 11 '10 at 8:17

. :

if( ! a[tabType]){

, .

-9

Jeremy Ruten 11 . '10 4:18

x1a4 · Accepted Answer · 2010-06-11T04:16:57+0000

The design !!forcibly converts to a boolean value. I do not see the point here.