What are the data types in javascript

There are six data types in JavaScript, which are string, number, boolean, null, undefined and object

JavaScript is a literal scripting language widely used on the client. It is a dynamically typed, weakly typed and prototype-based language. Its main function is to add dynamic functions to HTML web pages. Today I will introduce the types of data types in JavaScript, which has a certain reference effect and I hope it will be helpful to everyone.

[Recommended course: JavaScript Tutorial]

Every value in JavaScript belongs to a certain data type. There are six data types in JavaScript. They are undefined, null, boolean, number, string, object

They are divided into two categories, namely:

Basic types: String, number (Number), Boolean, Null, Undefined

Reference type: Object, Array, Function

String type

Strings can be represented by single quotes (') or double quotes (") to represent zero or more The character sequence composed of 16-bit Unicode characters is the string

var name="John"

Number type

JavaScript has only one number type. Numbers can have decimal points or Without

var X1=12.00;//使用小数点来写
var X2=12; //不使用小数点来写
//通过科学计数法来书写
var X=123e5;      // 12300000
var X=123e-5;     // 0.00123

Boolean type

It has two values: true and false, but it should be noted that true is not necessarily equal to 1, and false is not necessarily equal to 0.

And pay attention to case sensitivity when writing. True or False are not Boolean values, just identifiers. In JavaScript, the value can be converted into a Boolean value by calling the conversion function Boolean()

var x=true;
var y=false;

Undefined and Null

Undefined types. Executing the typeof operator on uninitialized and undeclared variables will return undefined

The Null type is the second data type with only one value, which is null. The null value represents a null pointer object, so the typeof operator returns "object" when detecting the null value

Object data type

Also known as an object, it is a collection of data and functions (functions). It can be created using the new operator followed by the name of the object type to be created. It can also be created using a literal Quantity notation is created. Add attributes with different names (any string including empty string).

var person={firstname:"John", lastname:"Doe", id:5566};

Summary: The above is the entire content of this article. I hope that this article can Help everyone understand and understand the data types in JavaScript

Note: This article refers to in JavaScript Tutorial JavaScript Data TypesSection

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