How to check if a variable is loaded in JavaScript?

Question

How do I see if a certain object has been loaded, and if not, how can it be loaded, like the following?

if (!isObjectLoaded(someVar)) {
    someVar= loadObject()         


        

Answer 1

If by loaded you mean defined, you can check the type of the variable with the typeof function. HOWEVER typeof has a few quirks, and will identify an Object, an Array, and a null as an object

alert(typeof(null));

Identifying a null as a defined object would probably cause your program to fail, so check with something like

if(null !== x && 'object' == typeof(x)){
    alert("Hey, It's an object or an array; good enough!");
}