How does javascript logical assignment work?

Question

In javascript, if we have some code such as

var a = \"one\";
var b = q || a;
alert (b);

The logical OR operator will assign a\'s value to b

Answer 1

The way || works in Javascript is:

1. If the left operand evaluates as true, return the left operand
2. Otherwise, return the right operand

&& works similarly.

You can make use of this for in-line existence checks, for example:

var foo = (obj && obj.property)

will set foo to obj.property if obj is defined and "truthy".