Shulou(Shulou.com)06/01 Report--

In this article Xiaobian for you to introduce in detail "what are the variables and data types of JavaScript", the content is detailed, the steps are clear, and the details are handled properly. I hope that this article "what are the variables and data types of JavaScript" can help you solve your doubts.

Variable

1. Declare a variable before assigning a value

Var width;width = 9

Var: is the keyword used to declare variables

Width: assign a value to a variable name

2. declare and assign variables at the same time

Var catName= "Xiaoming"; var x, y, z = 10

3. Do not declare direct assignment (rarely used)

Width = 5

Here the variable can be used directly without declaration, but it is easy to make mistakes, it is not easy to find and troubleshoot, and it is not recommended to use it.

Data type

1 、 undefined

Example: var width

Variable width has no initial value and will be assigned undefined

2 、 null

Represents a null value equal to undefined

3 、 number

Var num=23 / / is an integer at this time

Var num=23.0 / / floating point number at this time

4 、 Boolean

True and false, but JS resolves to 1 or 0

5 、 String

Text enclosed in single or double quotation marks

Var string = "This is a string"

After reading this, the article "what are the variables and data types of JavaScript" has been introduced. If you want to master the knowledge of this article, you still need to practice and use it yourself to understand it. If you want to know more about related articles, you are welcome to follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.