Usually, when I want to check the type of an object (whether it's an array, a NodeList, or whatever), I use the following:

var arr = [] // I don't do this, but it's for the sake of the example
var obj = {}
obj.toString.apply(arr) // This works

The question is: why can I not do the following?

var arr = []
{}.toString.apply(arr) // Syntax error: Unexpected token .

I don't get where the syntax error is.

I can do something approaching with [] though, the following works:

var nodeList = document.getElementsByClassName('foo')
[].forEach.call(nodeList, function(bar) { console.log(bar) }) // Works

So... I'm confused.

Usually, when I want to check the type of an object (whether it's an array, a NodeList, or whatever), I use the following:

var arr = [] // I don't do this, but it's for the sake of the example
var obj = {}
obj.toString.apply(arr) // This works

The question is: why can I not do the following?

var arr = []
{}.toString.apply(arr) // Syntax error: Unexpected token .

I don't get where the syntax error is.

I can do something approaching with [] though, the following works:

var nodeList = document.getElementsByClassName('foo')
[].forEach.call(nodeList, function(bar) { console.log(bar) }) // Works

So... I'm confused.

• javascript

• you forgot () in toString() ? – kappa Commented Apr 4, 2012 at 7:02
• Nope, see @Ray Toal's answer. Adding the parenthesis would lead to a syntax error (Object has no method 'apply'). – Florian Margaine Commented Apr 4, 2012 at 7:13
• Ahh.. i didn't thought that, it's correct – kappa Commented Apr 4, 2012 at 7:19

1 Answer 1

When you begin a line with { JavaScript thinks it starts a block statement, not an object literal. Parenthesize it and you will be okay.