When would you use document.write()? — When document.write() is executed after page load, it replaces the entire header and body tag with the given parameter value in string. An invocation could look like this: document.write(‘<h1>hello world</h1>’); When working with web application, it is uncommon task to overwrite an entire page, hence why using document.write() is bad…

Explain Function.prototype.bind — It took me awhile to understand how ‘this’ keyword works, but after reading about bind method, its starting to make sense regarding the context of an object set explicitly and being able to access with ‘this’ keyword. A common issue that arise when we use functions is dealing with a…

What’s the difference between .call and .apply? — Recalling the basics Remember, in JavaScript, everything are objects, even Functions, and every objects has their properties and methods. Both .apply and .call are methods of Function object. How do .apply or .call work? Invoking a function with .apply and .call allows us to point an object to the invoked function…

Difference between: function Person(){}, var person = Person(), and var person = new Person()? — There are different ways (not to be exact) we can use functions in JavaScript, but with the given code below highlights important differences on how functions work. function Person() {} Function Declaration Code above declares a function statement (statements perform an action) but does not execute, however, it does get registered…

What’s the difference between host objects and native objects? — From what I understand, objects are divided from which environment and language they are supplied: Host Objects and Native Objects. Host Objects are objects supplied by a certain environment. They are not always the same because each environment differs and contains host objects that accommodates execution of ECMAScript. Example, browser…

How do you organize your code? (module pattern, classical inheritance?) — There are several options in implementing Module Pattern. An option I mostly use is Object Literal Notation for encapsulating and organizing my code, but upon further readings, Module Pattern using Anonymous Closures, Global Import, and Module Export have sparked my interest as it provides more features for private and public…

What’s a typical use case for anonymous functions? — Since Anonymous Functions are function expressions rather than the regular function declaration which are statements. Function expressions are more flexible. We can assign functions to variables, object properties, pass them as arguments to other functions, and even write a simple one line code enclosed in an anonymous functions. Example: var…

What is a closure, and how/why would you use one? — Closures are inner functions inside of an outer function. They have their own local scope and has access to outer function’s scope, parameters (but NOT arguments object), and they also have access to global variables. From what I understand, Closures is a neat way to deal with scope issues. Reasons…

What’s the difference between a variable that is: null, undefined or undeclared? How would you go about checking for any of these states? — From what I understand, in Javascript, undefined and null are somewhat related on what value a variable contains. The case for undeclared differs. It tackles on how a variable is defined and how javascript treats these variables. So I am going to discuss undefined and null first since both are…