what does “object || {} ” means in javascript?

Question

I found below line of code in javascript application.

var auth = parent.auth = parent.auth || {};

I know there is existing Object parent wh

Answer 1

parent.auth || {} means if parent.auth is undefined, null or false in boolean case then new empty object will be initialized and assigned.

or you can understand it like:

var auth;
if(parent.auth){       
    auth=parent.auth;   
} else {
    auth={};   
}