semver

What is semver?

The semver package is a module for semantic versioning (semver) parsing and comparison. It provides utilities for working with semantic version numbers, allowing users to parse, compare, increment, and manipulate version numbers according to the semantic versioning specification.

What are semver's main functionalities?

Parsing and Validating Versions

This feature allows you to parse a version string and check if it is a valid semantic version.

"const semver = require('semver');
const version = '1.2.3';
const valid = semver.valid(version); // '1.2.3'"

Comparing Versions

This feature enables you to compare two semantic version numbers to determine their order.

"const semver = require('semver');
const v1 = '1.2.3';
const v2 = '4.5.6';
const comparison = semver.compare(v1, v2); // -1"

Incrementing Versions

This feature allows you to increment a version number by the major, minor, or patch version.

"const semver = require('semver');
const version = '1.2.3';
const incremented = semver.inc(version, 'patch'); // '1.2.4'"

Ranges and Satisfaction

This feature checks if a version satisfies a given range.

"const semver = require('semver');
const version = '1.2.3';
const range = '^1.0.0';
const satisfied = semver.satisfies(version, range); // true"

Coercion

This feature coerces a string to a semantic version if possible.

"const semver = require('semver');
const version = 'v1';
const coerced = semver.coerce(version); // '1.0.0'"

Other packages similar to semver

compare-versions

This package provides a simple way to compare version numbers. While semver offers a full suite of semantic versioning features, compare-versions focuses solely on the comparison aspect, making it a lighter alternative for this specific use case.

node-semver

This is an alternative package that also implements the semantic versioning specification. It is similar to semver but may have different APIs or additional features.

validate-version

This package is used to validate version numbers against the semantic versioning specification. Unlike semver, which offers a broad range of versioning utilities, validate-version is specifically tailored for validation.

README

semver(1) -- The semantic versioner for npm

Usage

$ npm install semver

semver.valid('1.2.3') // '1.2.3'
semver.valid('a.b.c') // null
semver.clean('  =v1.2.3   ') // '1.2.3'
semver.satisfies('1.2.3', '1.x || >=2.5.0 || 5.0.0 - 7.2.3') // true
semver.gt('1.2.3', '9.8.7') // false
semver.lt('1.2.3', '9.8.7') // true

As a command-line utility:

$ semver -h

Usage: semver <version> [<version> [...]] [-r <range> | -i <inc> | -d <dec>]
Test if version(s) satisfy the supplied range(s), and sort them.

Multiple versions or ranges may be supplied, unless increment
or decrement options are specified.  In that case, only a single
version may be used, and it is incremented by the specified level

Program exits successfully if any valid version satisfies
all supplied ranges, and prints all satisfying versions.

If no versions are valid, or ranges are not satisfied,
then exits failure.

Versions are printed in ascending order, so supplying
multiple versions to the utility will just sort them.

Versions

A "version" is described by the v2.0.0 specification found at http://semver.org/.

A leading "=" or "v" character is stripped off and ignored.

Ranges

The following range styles are supported:

• 1.2.3 A specific version. When nothing else will do. Must be a full version number, with major, minor, and patch versions specified. Note that build metadata is still ignored, so 1.2.3+build2012 will satisfy this range.
• >1.2.3 Greater than a specific version.
• <1.2.3 Less than a specific version. If there is no prerelease tag on the version range, then no prerelease version will be allowed either, even though these are technically "less than".
• >=1.2.3 Greater than or equal to. Note that prerelease versions are NOT equal to their "normal" equivalents, so 1.2.3-beta will not satisfy this range, but 2.3.0-beta will.
• <=1.2.3 Less than or equal to. In this case, prerelease versions ARE allowed, so 1.2.3-beta would satisfy.
• 1.2.3 - 2.3.4 := >=1.2.3 <=2.3.4
• ~1.2.3 := >=1.2.3-0 <1.3.0-0 "Reasonably close to 1.2.3". When using tilde operators, prerelease versions are supported as well, but a prerelease of the next significant digit will NOT be satisfactory, so 1.3.0-beta will not satisfy ~1.2.3.
• ^1.2.3 := >=1.2.3-0 <2.0.0-0 "Compatible with 1.2.3". When using caret operators, anything from the specified version (including prerelease) will be supported up to, but not including, the next major version (or its prereleases). 1.5.1 will satisfy ^1.2.3, while 1.2.2 and 2.0.0-beta will not.
• ^0.1.3 := 0.1.3 "Compatible with 0.1.3". 0.x.x versions are special: since the semver spec specifies that 0.x.x versions make no stability guarantees, only the version specified is considered valid.
• ^0.0.2 := 0.0.2 "Only the version 0.0.2 is considered compatible"
• ~1.2 := >=1.2.0-0 <1.3.0-0 "Any version starting with 1.2"
• ^1.2 := >=1.2.0-0 <2.0.0-0 "Any version compatible with 1.2"
• 1.2.x := >=1.2.0-0 <1.3.0-0 "Any version starting with 1.2"
• 1.2.* Same as 1.2.x.
• 1.2 Same as 1.2.x.
• ~1 := >=1.0.0-0 <2.0.0-0 "Any version starting with 1"
• ^1 := >=1.0.0-0 <2.0.0-0 "Any version compatible with 1"
• 1.x := >=1.0.0-0 <2.0.0-0 "Any version starting with 1"
• 1.* Same as 1.x.
• 1 Same as 1.x.
• * Any version whatsoever.
• x Same as *.
• "" (just an empty string) Same as *.

Ranges can be joined with either a space (which implies "and") or a || (which implies "or").

Functions

All methods and classes take a final loose boolean argument that, if true, will be more forgiving about not-quite-valid semver strings. The resulting output will always be 100% strict, of course.

Strict-mode Comparators and Ranges will be strict about the SemVer strings that they parse.

• valid(v): Return the parsed version, or null if it's not valid.
• inc(v, release): Return the version incremented by the release type (major, premajor, minor, preminor, patch, prepatch, or prerelease), or null if it's not valid
  • premajor in one call will bump the version up to the next major version and down to a prerelease of that major version. preminor, and prepatch work the same way.
  • If called from a non-prerelease version, the prerelease will work the same as prepatch. It increments the patch version, then makes a prerelease. If the input version is already a prerelease it simply increments it.

Comparison

• gt(v1, v2): v1 > v2
• gte(v1, v2): v1 >= v2
• lt(v1, v2): v1 < v2
• lte(v1, v2): v1 <= v2
• eq(v1, v2): v1 == v2 This is true if they're logically equivalent, even if they're not the exact same string. You already know how to compare strings.
• neq(v1, v2): v1 != v2 The opposite of eq.
• cmp(v1, comparator, v2): Pass in a comparison string, and it'll call the corresponding function above. "===" and "!==" do simple string comparison, but are included for completeness. Throws if an invalid comparison string is provided.
• compare(v1, v2): Return 0 if v1 == v2, or 1 if v1 is greater, or -1 if v2 is greater. Sorts in ascending order if passed to Array.sort().
• rcompare(v1, v2): The reverse of compare. Sorts an array of versions in descending order when passed to Array.sort().

Ranges

• validRange(range): Return the valid range or null if it's not valid
• satisfies(version, range): Return true if the version satisfies the range.
• maxSatisfying(versions, range): Return the highest version in the list that satisfies the range, or null if none of them do.
• gtr(version, range): Return true if version is greater than all the versions possible in the range.
• ltr(version, range): Return true if version is less than all the versions possible in the range.
• outside(version, range, hilo): Return true if the version is outside the bounds of the range in either the high or low direction. The hilo argument must be either the string '>' or '<'. (This is the function called by gtr and ltr.)

Note that, since ranges may be non-contiguous, a version might not be greater than a range, less than a range, or satisfy a range! For example, the range 1.2 <1.2.9 || >2.0.0 would have a hole from 1.2.9 until 2.0.0, so the version 1.2.10 would not be greater than the range (because 2.0.1 satisfies, which is higher), nor less than the range (since 1.2.8 satisfies, which is lower), and it also does not satisfy the range.

If you want to know if a version satisfies or does not satisfy a range, use the satisfies(version, range) function.