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npm Basics

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Semantic Versioning

4:42 with Reggie Williams

Semantic Version is a system for communicating changes in versions of projects.

Further Reading

Semantic Versioning

  • MAJOR.MINOR.PATCH
  • ^ before a version number means install up to the latest MINOR release.
    • e.g. ^1.1 can install 1.3 if available but not 2.0
  • ~ before a version number means install up to the latest PATCH release.
    • e.g. ~2.0.1 can install 2.0.9 if available but not 2.1.0

Terminal Commands

  • Clear the screen
    • clear

npm Command Line Usage

  • See list of commands

    • npm

  • Installing a packages from package.json

    • npm install

  • Check for outdated packages

    • npm outdated

  • Update packages in your project

    • For local packages npm update
    • For global packages npm update <package name> -g
      • e.g. npm update http-server -g

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    You may begin to notice that NPM packages are often referred to by 0:00
    a combination of the name of the package followed by a version number. 0:04
    An individual package can have hundreds of versions and 0:10
    between these versions there may be small or large changes. 0:15
    Some versions may be fixes of bugs from previous versions. 0:19
    Some newer versions would break projects that rely on previous versions. 0:24
    We can gather all of this information from the version number. 0:30
    [SOUND] Package version numbers, consist of three numbers, separated by periods. 0:35
    This style of numbering is called semantic versioning or SemVer for short. 0:43
    NPM relies on semantic versioning to communicate differences in updates, 0:48
    determine which packages to install, and more. 0:53
    The first number is the major version number. 0:57
    This changes for example, when a project goes from version one to version two, 1:01
    it means there are breaking changes. 1:07
    Breaking changes mean that an app using v1 might break when the package 1:09
    is updated to v2. 1:14
    The second number is for minor or patch changes. 1:15
    From version 1.1 to 1.2, there may be small changes that 1:20
    shouldn't affect apps relying on previous versions. 1:25
    Finally, the last number represents bug fixes. 1:30
    These are normally small fixes of bugs from previous versions that 1:35
    shouldn't have any other effects. 1:39
    Along with version numbers, semantic versioning uses symbols to 1:41
    indicate ranges of acceptable versions of a package. 1:46
    We'll learn more about installing packages in the next video. 1:50
    But let's first turn our attention to these symbols and how we use them. 1:54
    The caret symbol is used to refer to all greater versions in the same major range. 2:01
    With the caret, there can be minor differences in versions, but 2:08
    nothing should break. 2:11
    The tilde refers to all versions greater 2:13
    than a given version in the same minor range. 2:16
    This means all versions greater than the given version that have 2:20
    the same middle digit. 2:24
    We can also define ranges using greater than, less than and 2:28
    other comparison operators. 2:32
    We can use a tool called semver calculator to visualize all of this. 2:35
    We give semver calculator a package name and a version number. 2:39
    Here it has a popular JavaScript utility library lodash. 2:44
    We'll borrow the rain from the example below. 2:52
    When we enter a range using a caret in the number 2.2.1, 3:02
    all of the minor updates after 2.2.1 are highlighted. 3:07
    Changing this to a tilde highlights the single bug update for version 2.2. 3:18
    The greater than or equal sign gives us a range of everything beyond and 3:23
    including 2.21. 3:29
    Notice if we type 0.0, 3:35
    most of the packages are highlighted, but some are not. 3:38
    This is because by default, pre release versions are not included. 3:45
    These versions may have experimental features that aren't added for 3:50
    the long term. 3:54
    Because of this, 3:56
    you'll generally want to avoid using these versions in production code. 3:57
    To review, [SOUND] major changes are the most important to watch out for 4:03
    and may require refactoring. 4:08
    Minor changes typically won't affect your apps. 4:10
    Bug fixes are usually beneficial and 4:13
    shouldn't have any other effects on your apps. 4:15
    Knowing more about versioning we can better decide which package and 4:19
    version to include in our projects. 4:23
    In the upcoming videos, where we learn more about working with packages, 4:26
    we'll also learn how we can install or update to a specific version of a package. 4:30
    This will give you more control over exactly which code you're using 4:36
    in your apps. 4:40

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