There are several types of javascript

JavaScript is a very popular scripting language that is widely used in web pages, web applications and mobile application development. In JavaScript, data types are very important concepts. They define what types of values ​​the data can store and what operations can be performed on those values. This article will introduce various data types and their characteristics in JavaScript.

1. Basic data types

1.Number

Numeric data types are used to store numerical values, including integers, floating point numbers, negative numbers, etc. In JavaScript, numeric data types use double-precision floating point to store values, and can also be represented using scientific notation.

Example: let age = 26; // Integer

let pi = 3.1415926; // Floating point number

let debt = -2000; // Negative number

2. String (String)

The string data type is a sequence of characters, usually used to store text information. In JavaScript, strings need to be enclosed in single quotes, double quotes, or backticks.

Example: let name = "Tom"; // Double quotes

let message = 'Hello, world'; // Single quotes

let template = My name is ${name}; // Backtick

3. Boolean

The Boolean data type has only two values, namely true and false. Boolean types are usually used to determine conditional expressions of statements or to control program flow.

Example: let isAdult = true; // Adults

let hasChildren = false; // No children

4. Null value(Null)

The null value data type represents a null value or a non-existent object. In JavaScript, the null value has only one value, null. null is used to represent a non-existent or invalid value.

Example: let empty = null; // Empty value

2. Reference data type

5. Object(Object)

The object data type is A composite data type that can store multiple key-value pairs. Objects in JavaScript can include functions, arrays, dates, etc. It is one of the most basic data types in JavaScript.

Example: let person = { name: "Tom", age: 26 };

let book = { name: "Advanced Programming with JavaScript", author: "Nicholas C. Zakas" };

6. Array

The array data type is an ordered collection that can store multiple values, and each value can be of any data type. In JavaScript, arrays are represented by square brackets [], with elements separated by commas.

Example: let list = [1, 2, 3, 4, 5];

let books = ["JavaScript Advanced Programming", "JavaScript Authoritative Guide", "In-depth explanation of Node. js"];

7. Function

The function data type is a reusable block of code that can accept parameters, perform logical operations, and return a value. In JavaScript, functions are a special type of object that can be stored in variables or passed as parameters to other functions.

Example: function add(a, b) {

return a b;

}

8. Date (Date)

The date data type is used to store date and time information. In JavaScript, dates are represented by Date objects, which are used to handle timestamps, date formatting, and calculating intervals between dates.

Example: let now = new Date();

let today = new Date("2021-05-01");

9. Regular expression (RegExp )

Regular expression data type is used to match patterns in text. In JavaScript, regular expressions are represented using RegExp objects and are used to examine and modify text in strings.

Example: let pattern = /JavaScript/;

let result = "JavaScript Advanced Programming".match(pattern);

The above are all data types in JavaScript . For different data types, we can choose different operations and methods to achieve different functions. Therefore, when writing JavaScript programs, it is very important to understand the characteristics and usage of data types.

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