JavaScript object add item

Introduction. Objects in JavaScript are collections of key/value pairs . The values can consist of properties and methods, and may contain all other JavaScript data types, such as strings, numbers, and Booleans. All objects in JavaScript descend from the parent Object constructor.

A class defines object properties including a valid range of values, and a default value. A class also describes object behavior. An object is a member or an “instance” of a class. An object has a state in which all of its properties have values that you either explicitly define or that are defined by default settings.

In JavaScript, an object is a standalone entity, with properties and type . Compare it with a cup, for example. A cup is an object, with properties. A cup has a color, a design, weight, a material it is made of, etc.

Classes are a template for creating objects . They encapsulate data with code to work on that data. Classes in JS are built on prototypes but also have some syntax and semantics that are not shared with ES5 class-like semantics.18 Şub 2022