Why don't logical operators (&& and ||) always return a boolean result?

Question

Why do these logical operators return an object and not a boolean?

var _ = (obj.fn && obj.fn() ) || obj._ || ( obj._ = {} );

var _ = obj &&          


        

Answer 1

We can refer to the spec(11.11) of JS here of:

Semantics

The production LogicalANDExpression :LogicalANDExpression &&BitwiseORExpression is evaluated as follows:

1. Evaluate LogicalANDExpression.

2.Call GetValue(Result(1)).

3.Call ToBoolean(Result(2)).

4.If Result(3) is false, return Result(2).

5.Evaluate BitwiseORExpression.

6.Call GetValue(Result(5)).

7.Return Result(6).

see here for the spec