Package What is the function of JSON file? What do the inside ^ angle brackets and ~ tilde mean?

1、package.json What is the function of documents ？

package.json It is the description file of the package , There are mainly the following 3 A role ：

（1） It is equivalent to a document description of your local project .
（2） Allows you to specify the node The version of the package .
（3） It's easier to build your project , Easy to share with others .

2、package.json In file ^ Angle brackets and ~ What does the wave sign mean ？

according to package The second rule about the role of documents is ： This file specifies the node The version of the package , stay package.json Inside dependencies There are two symbols in front of the version number of the dependent package , One is ~, One is ^.

（1）^ Express ： Match the latest large version, such as 1.0.2 Will match to 1.x.x, But does not include 2.x.x
（2）~ Express ： Match the latest small version, such as ~1.0.2 Will match 1.0.x edition , But don't match 1.1.0

PS： Software version number x.y.z The meaning of ：
z ： It means some small ones bugfix, change z Of ,
y ： Indicates some major version changes , For example, some API The change of
x ： It indicates some design changes and module reconfiguration , It will be upgraded x Version number