semver(1) -- The semantic versioner for npm


$ 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'1.2.3', '9.8.7') // false'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.


A "version" is described by the v2.0.0 specification found at

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


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.
  • ^1.2.3 := >=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 := >=0.1.3-0 <0.2.0-0 "Compatible with 0.1.3". 0.x.x versions are special: the first non-zero component indicates potentially breaking changes, meaning the caret operator matches any version with the same first non-zero component starting at the specified version.
  • ^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 := >=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"

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


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.


  • 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().


  • 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.