Understanding JavaScript: New Keyword

One specific part of the JavaScript language that brings a lot of misunderstanding with it is the keyword. If JS is not your first programming language and you have done some OOP, you are undoubtedly used to seeing the keyword used whenever a class is instantiated. new new Thanks to all the features that came to JavaScript with ES6 the code snippet above works exactly as you would expect. The typical behavior in languages that have classes is pretty straight forward. The arguments are passed to the constructor function of the class and it gives you a new object. While the JavaScript syntax is visually the same it is only syntactic sugar to what happens under the hood. There are no constructors The first thing we need to get out of the way is that we don’t need to have a class in order to use . In JavaScript we can use a function instead of a class to achieve the same result. In fact, we can technically call any function with before it. new new Functions that are called with the keyword are usually called constructor functions. However, we could argue that there are no constructor functions, only constructor calls since any function can be used as a constructor. new Here will be assigned an empty object as a value since no bindings were made inside the function. It doesn't matter what the function's return value is - if we make a constructor call we will always receive an object. variable getName Constructor calls There are a few things that happen whenever we call a function with : new A new object is created is bound to the new object this The new object is returned, the function returns its own object unless The newly created object is assigned as value to the variable In other words, we tell JavaScript to execute a function and return an object. Any bindings in the function are made on the object being returned. this Even though a name is added to , since the function returns an object it will be used rather than the regular binding. this ES6 From ES6 forward we can use the class syntax and the constructor like in typical object oriented languages. I find this to be a great addition since it makes the language more accessible to people comming from an OO language. Still, it’s important to note that classes are just syntactic sugar on top of JavaScript’s existing functionality. If you’re interested in more JS related content you can subscribe to my newsletter from or you can take a look at the other articles from the same series: here _Due to the amazing quantity of libraries, tools and all kinds of things that make your development easier, a lot of…_hackernoon.com Understanding JavaScript: Scope _Due to the amazing quantity of libraries, tools and all kinds of things that make your development easier, a lot of…_hackernoon.com Understanding JavaScript: Prototype and Inheritance _Due to the amazing quantity of libraries, tools and all kinds of things that make your development easier, a lot of…_hackernoon.com Understanding JavaScript: This Keyword _Due to the amazing quantity of libraries, tools and all kinds of things that make your development easier, a lot of…_hackernoon.com Understanding JavaScript: New Keyword _Due to the amazing quantity of libraries, tools and all kinds of things that make your development easier, a lot of…_hackernoon.com Understanding JS: Coercion _Due to the amazing quantity of libraries, tools and all kinds of things that make your development easier, a lot of…_hackernoon.com Understanding JS: The Event Loop