Javascript lost context when assigned to other variable

Question

Why in javascript if you reference objects method to some variable it loses that objects context. Can\'t find any link with explanation what happens under the hood. Except t

Answer 1

From Douglas Crockford's book JavaScript: The Good Parts

The this parameter is very important in object oriented programming, and its value is determined by the invocation pattern. There are four patterns of invocation in JavaScript: the method invocation pattern, the function invocation pattern, the constructor invocation pattern, and the apply invocation pattern. The patterns differ in how the bonus parameter this is initialized

The Method Invocation Pattern

When a function is stored as a property of an object, we call it a method. When a method is invoked, this is bound to that object. If an invocation expression contains a refinement (that is, a . dot expression or[subscript] expression), it is invoked as a method

In your example method invocation pattern is

console.log(obj.method() === 1);

and this in this case is bound to the object "Class" and it works as you expected.

The Function Invocation Pattern

When a function is not the property of an object, then it is invoked as a function:

var sum = add(3, 4); // sum is 7

When a function is invoked with this pattern, this is bound to the global object. This was a mistake in the design of the language. Had the language been designed correctly, when the inner function is invoked, this would still be bound to the this variable of the outer function. A consequence of this error is that a method cannot employ an inner function to help it do its work because the inner function does not share the method’s access to the object as its this is bound to the wrong value

In your case

var refToMethod = obj.method; // why refToMethod 'this' is window
console.log(refToMethod() !== 1) // why this is true?

refToMethod is bound to the global object "window" in this case

You can find more information about this at JavaScript “this” keyword