CODEWITHSUNDEEP
javascript
Florian Margaine
Florian Margaine

Reputation: 60767

Why doesn't `{}.toString.apply(array)` work?

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.

Upvotes: 7

Views: 392

Answers (1)

Ray Toal
Ray Toal

Reputation: 88378

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

Upvotes: 16

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