JavaScript Data Types

Every programming language is designed around storing information for your application or website. When storing this information, there is always a need to specify what kind of information is being stored. It could be numerical information or textual data. Sometimes it could be a logical state and sometimes it is a collection or list of information. Hence, every programming language ships with built-in data types also known as primitive data types.

JavaScript as a language provides the following eight basic data types:

• Number
• String
• Boolean
• Null
• Undefined
• BigInt
• Symbol
• Object

Here is a brief description of each of the eight basic JavaScript data types:

Number in JavaScript represents integer numbers or a floating-point number. A number type could also be +Infinity, -Infinity, and NaN (not a number).

The string type is used to represent textual data.

The boolean data type represents logical entities. Boolean values represent truth values: true or false.

Null in JavaScript represents an unknown or empty value.

The undefined data type represents a variable that has not been assigned a value.

BigInt can represent integers with arbitrary precision, allowing you to store and operate on larger numbers beyond the integer limit.

If a value has the symbol data type, it is an immutable and unique primitive value.

The non-primitive, complex data type object allows you to store multiple data collections. Arrays are a type of object whose keys are integers. Arrays are a key building block for complex data structures.

It is important to note that JavaScript is a dynamic and weakly typed language, so the same variable can be used to hold a variety of different data types. JavaScript variables assigned a value of a certain type can be re-assigned a value of a different type because they are dynamically used by the JavaScript engine.

Considering JavaScript is a weakly-typed, dynamic language, it also provides Developers with typeof operator that helps to understand the data type being stored in a certain variable at any given point in time.

const grade = 100;
console.log(typeof grade); // prints number

const greeting = ‘Merry Christmas’;
console.log(typeof greeting); // prints string

const hasGraduated = true;
console.log(typeof hasGraduated); // prints boolean

Sometimes while using strings in JavaScript, there is a need to know the length of the string or textual information stored in a JavaScript variable. JavaScript provides length property for the same. length property is commonly used when there is a need to find the length of a string or many other data types in JavaScript.