if array exists, then continue

Question

Hi,

I have an array that might be present in my .aspx page, if it is, I want to fire a javascript function.

I tried:

if(someArray)
       blah(someArray);

but I get an error when I havent' defined someArray.

Answer 1

if(typeof someArray !== 'undefined') {
    blah(someArray);
}

Answer 2

You should probably be pre-defining the array as null and check to see if it resolves, rather than sometimes available.

Array someArray = null;

// this is where you'll populate or replace someArray
// if you don't, someArray simply remains empty

if (someArray)
{
    ...
}

Answer 3

var a = [];
var b = new Array();
alert(typeof a === "object" && a instanceof Array);
alert(typeof b === "object" && b instanceof Array);
alert(typeof c === "object" && c instanceof Array);