# semver

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. 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` := `>=1.2.0-0 <1.3.0-0` "Any version starting with 1.2"
- `1.2.x` := `>=1.2.0-0 <1.3.0-0` "Any version starting with 1.2"
- `~1` := `>=1.0.0-0 <2.0.0-0` "Any version starting with 1"
- `1.x` := `>=1.0.0-0 <2.0.0-0` "Any version starting with 1"

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, minor, patch, or prerelease), or null if it's not valid.

### 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.