Define Property In The Object Prototype And Get The Object's Type

I have created a property on the Object's prototype that is an object with some functions: Object.defineProperty(Object.prototype, 'json', { value: function() { re

Solution 1:

What you are looking for is instanceof operator:

("simple string".json()._value) instanceofString  ===  true

Solution 2:

For not getting the this value casted to an object, you can use strict mode:

Object.defineProperty(Object.prototype, "json", {
    value: function() {
        "use strict";
        return {
            _value: this,
            parse: function() {
            }
        };
    }
});
typeof"simple string".json()._value// "string"typeofnewString("simple string").json()._value// "object"