In my particular case:  callback instanceof Function   or   typeof callback == "function"   does it even matter, what's the difference?  Additional Resource:  JavaScript-Garden typeof vs instanceof...

I'm trying to use some of the more advanced OO features of Javascript, following Doug Crawford's "super constructor" pattern. However, I don't know how to set and get types from my objects using Javascript's native type system...

I'm reading through the code of the class-validator library and it has the following isInstance method in it:  /**  * Checks if the value is an instance of the specified object.  */ isInstance(object: any, targetTypeConstructor: new (...args: any...

In Stoyan Stefanov's book Object-Oriented javascript, on page 103 he has the following.  However when I try this, I get a different result with h instanceof Object. Am I missing something, has something in JS changed since or is this an error in...

What is the best way to determine a JavaScript object's prototype?  I am aware of the following two methods, but I'm not sure which is the "best" way (or if there's a better preferred way) in terms of cross-browser support.  if (o...

How do you detect if a function is a method for a jQuery element?  For example, $.fn.fadeIn is a function:        typeof $.fn.fadeIn === 'function'  //true  However, I need a way to distinguish it from a regular non-jQuery method.  The goa...

I am very new to JavaScript and could not understand the code below (code source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof)  // defining constructors function C(){} function D(){}  var o = new C();  // tr...

In JavaScript there's a pattern to achieve inheritance called "Functional inheritance" described in chapter 5 of Crockfords "JavaScript: the good parts".  One of the disadvantages of the pattern -- as compared to using the pseudo-...

var Person = function(name, age){     return Object.create(Object.prototype, {         name: {             value: name | "",             writable: true,             enumerable: true,             configurable: true         },         age: {...

I have the following javascript code:  function testClass() {     this.SaveValue = function (value) {         var isInstance = value instanceof TestEnum;          if (!isInstance) {             return;         }      } }  TestEnum = {     VALUE_0: 0,...