Question

what exactly is going on with this javascript statement:

var loadPrevious = (loadPrevious || function() {});

From my understanding, the variable loadPrevious is either going to be an anonymous function or the value loadPrevious

EDIT:

ok great thanks for the answers and comments. But why then would there be a statement like this:

var app;
loadPrevious(app = launchApplication($("#target"),0));

what does loadPrevious do here? And why do it this way?

Answer 1

it checks to see if loadPrevious has already been assigned a value. if not, it assigns it an empty function.

this syntax is the javascript equivalent of the C++ or C# ternary syntax

var loadPrevious = loadPrevious != null ? loadPrevious : () => {}; 

in C#, for example.