Shorthand if/else statement Javascript

Question

I'm wondering if there's a shorter way to write this:

var x = 1; if(y != undefined) x = y; 

I initially tried x = y || 1, but that didn't work. What's the correct way to go about this?

Answer 1

var x = y !== undefined ? y : 1; 

Note that var x = y || 1; would assign 1 for any case where y is falsy (e.g. false, 0, ""), which may be why it "didn't work" for you. Also, if y is a global variable, if it's truly not defined you may run into an error unless you access it as window.y.

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As vol7ron suggests in the comments, you can also use typeof to avoid the need to refer to global vars as window.<name>:

var x = typeof y != "undefined" ? y : 1; 

Answer 2

Another way to write it shortly

bePlanVar = !!((bePlanVar == false));  // is equivalent to  bePlanVar = (bePlanVar == false) ? true : false;  // and   if (bePlanVar == false) {     bePlanVar = true; } else {     bePlanVar = false; }