How to distinguish JavaScript Built-in Object

Question

I'm currently learning JavaScript from ECMA Manual, and I'm confused with the concept of built-in object. I know that object like Function, Object, Math are built-in objects, and you can use them directly, e.g, Math.PI. But how about var obj = new Function('return a'), Can I call obj a built-in object? Or is it just a plain native object (but not built-in)? Thanks!

Edit: Definition from ECMA

What is the difference between native and built-in for you? Either way, since you created obj, it's probably not a built-in object. It doesn't exist in another JS system. — Felix Kling
– Felix Kling, Commented Feb 19, 2015 at 16:16
Easy way to tell if its built in is if you log it and it returns "[native code]" in the function body, eg String returns function String() { [native code] } — user2033671
– user2033671, Commented Feb 19, 2015 at 16:26

Oriol · Accepted Answer · 2015-02-19 16:24:46Z

3

4.3.7 built-in object

object supplied by an ECMAScript implementation, independent of the host environment, that is present at the start of the execution of an ECMAScript program

You create the object obj. That means it wasn't present at the start of the execution of the ECMAScript program. Therefore, it isn't a built-in object.

answered Feb 19, 2015 at 16:24

Oriol

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