Why I can do if else shorthand inside .push() function ? like

var arr = [];
arr.push(test||null);
// nothing

But

var arr = [];
var test = test||null;
arr.push(test);
// [null]

I need to insert null if variable is undefined.

Why I cant use test||null inside .push() function ?

Why I can do if else shorthand inside .push() function ? like

var arr = [];
arr.push(test||null);
// nothing

But

var arr = [];
var test = test||null;
arr.push(test);
// [null]

I need to insert null if variable is undefined.

Why I cant use test||null inside .push() function ?

• javascript
• arrays
• if-statement
• push
• array-push

• Your first example causes an error, that's why nothing happens. Please take a look at the console. – Teemu Commented Oct 15, 2013 at 8:04

2 Answers 2

arr.push(typeof(test) == "undefined" ? null: test);

Yes. You can use

arr.push(test||null);

if you define test. Why your second code is working ?

var arr = [];
var test = test||null;
arr.push(test);
// [null]

It's working because you have defined test.

So, this works

var test;
var arr = [];
arr.push(test||null);