What is the best way to check if an object is an array or not in Javascript?

Question

Say I have a function like so:

function foo(bar) {
    if (bar > 1) {
       return [1,2,3];
    } else {
       return 1;
    }
}

And s

Answer 1

Here is one very reliable way, take from Javascript: the good parts, published by O'Reilly:

if (my_value && typeof my_value === 'object' &&  typeof my_value.length === 'number' &&
!(my_value.propertyIsEnumerable('length')) { // my_value is truly an array! }

I would suggest wrapping it in your own function:

function isarray(my_value) {

    if (my_value && typeof my_value === 'object' &&  typeof my_value.length === 'number' &&
        !(my_value.propertyIsEnumerable('length')) 
         { return true; }
    else { return false; }
}