Implicit type coercion with objects

Question

var a = {};
a + 1 // return "[object Object]1"

I know why this happened. Object toPrimitive happened and after a.toString return [object Object] and merge with number But why when I type code like this

{} + 1 // return 1

Object not converted string?

Also why object toPrimitive hint Number return 0 When object convert to number this is look valueOf function and why valueOf return 0?

Answer 1

First one is an object and you're adding object with number

var a = {};
a + 1 // return "[object Object]1"

Where as second one is just block statement not object

{} + 1 // return 1