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

IMHO - don't use for boolean type assignment. It can be confusing. As undefined !== false, ie false itself is a value.

E.g. If u want to copy a field value from an object if and only if that field is defined

var bar.value = false;
var foo = true;

var foo = bar.value || foo;  // ==> should be false as bar.value is defined

For boolean type assignment, u should really use

var foo = (bar.value !== undefined) ? bar.value : foo;