JavaScript is a prototype-based language — an object's behaviors are specified by its own properties and its prototype's properties. However, with the addition of classes, the creation of hierarchies of objects and the inheritance of properties and their values are much more in line with other object-oriented languages such as Java. In this section, we will demonstrate how objects can be created from classes.

Whereas HTML defines a webpage's structure and content and CSS sets the formatting and appearance, JavaScript adds interactivity to a webpage and creates rich web applications.

Low-level languages like C, have manual memory management primitives such as malloc() and free(). In contrast, JavaScript automatically allocates memory when objects are created and frees it when they are not used anymore (garbage collection). This automaticity is a potential source of confusion: it can give developers the false impression that they don't need to worry about memory management.

This chapter documents all of JavaScript's standard, built-in objects, including their methods and properties.

Functions are one of the fundamental building blocks in JavaScript. A function in JavaScript is similar to a procedure—a set of statements that performs a task or calculates a value, but for a procedure to qualify as a function, it should take some input and return an output where there is some obvious relationship between the input and the output. To use a function, you must define it somewhere in the scope from which you wish to call it.

Boolean values can be one of two values: true or false, representing the truth value of a logical proposition.

Operator precedence determines how operators are parsed concerning each other. Operators with higher precedence become the operands of operators with lower precedence.

The parseInt() function parses a string argument and returns an integer of the specified radix (the base in mathematical numeral systems).

The unsigned right shift (>>>) operator returns a number whose binary representation is the first operand shifted by the specified number of bits to the right. Excess bits shifted off to the right are discarded, and zero bits are shifted in from the left. This operation is also called "zero-filling right shift", because the sign bit becomes 0, so the resulting number is always positive. Unsigned right shift does not accept BigInt values.

The if...else statement executes a statement if a specified condition is truthy. If the condition is falsy, another statement in the optional else clause will be executed.