Extracting Components

Relevant source files

The following files were used as context for generating this wiki page:

• functions/major.js
• functions/minor.js
• functions/patch.js
• functions/prerelease.js
• classes/semver.js
• semver.js
• functions/parse.js
• internal/re.js

Extracting components is a core capability of the node-semver library, allowing developers to isolate specific parts of a Semantic Versioning string, such as the major, minor, or patch versions, as well as prerelease identifiers and build metadata. This process relies on a robust parsing engine that validates input strings against the SemVer 2.0.0 specification before decomposition.

The system utilizes specialized functions and a central SemVer class to provide both functional and object-oriented interfaces for data extraction. These operations are critical for version comparison logic, range satisfaction checks, and automated version bumping. Sources: semver.js:24, index.js:12-16

Core Extraction Functions

The library provides several top-level functions designed for quick extraction of specific version segments. Most of these functions serve as wrappers that instantiate a SemVer object and return the requested property.

Primary Extraction API

Function	Extracted Component	Return Type	Description
major(v, options)	Major Version	Number	Returns the first numeric identifier (X.0.0).
minor(v, options)	Minor Version	Number	Returns the second numeric identifier (0.X.0).
patch(v, options)	Patch Version	Number	Returns the third numeric identifier (0.0.X).
prerelease(v, options)	Prerelease Tags	Array	Returns an array of dot-separated prerelease identifiers, or null.

Sources: functions/major.js:5, functions/minor.js:5, functions/patch.js:5, functions/prerelease.js:12

Extraction Logic Flow

The following diagram illustrates the typical flow when calling an extraction function like major().

The SemVer Class Extraction Architecture

The SemVer class serves as the primary data structure for held version information. When a string is parsed into a SemVer instance, the constructor decomposes the string into several internal properties.

Component Properties

Upon successful instantiation, the following properties are made available:

• major: The major version number. Sources: classes/semver.js:51
• minor: The minor version number. Sources: classes/semver.js:52
• patch: The patch version number. Sources: classes/semver.js:53
• prerelease: An array of prerelease identifiers, with numeric segments converted to actual numbers for proper comparison. Sources: classes/semver.js:68-79
• build: An array of build metadata identifiers. Sources: classes/semver.js:82
• version: A formatted string containing major.minor.patch (and prerelease if applicable). Sources: classes/semver.js:86-91

Data Extraction Sequence

This sequence diagram shows how the SemVer constructor extracts components using internal regex tokens.

Technical Implementation Details

Numeric Boundaries

During extraction, the library enforces safety limits defined in internal/constants.js. Components are validated against MAX_SAFE_INTEGER (9007199254740991). If an extracted component exceeds this value, the constructor throws a TypeError. Sources: internal/constants.js:7, classes/semver.js:55-65

Prerelease and Build Splitting

Prerelease and build identifiers are extracted by splitting the captured strings from the regular expression by the dot (.) character.

this.prerelease = m[4].split('.').map((id) => {
  if (/^[0-9]+$/.test(id)) {
    const num = +id
    if (num >= 0 && num < MAX_SAFE_INTEGER) {
      return num
    }
  }
  return id
})
this.build = m[5] ? m[5].split('.') : []

Sources: classes/semver.js:69-82

Regex Capturing Groups

The extraction mechanism relies on specific capturing groups within the FULL and LOOSE regular expressions defined in internal/re.js:

1. Group 1: Major version Sources: internal/re.js:74
2. Group 2: Minor version Sources: internal/re.js:75
3. Group 3: Patch version Sources: internal/re.js:76
4. Group 4: Prerelease string (everything after the first -) Sources: internal/re.js:101
5. Group 5: Build string (everything after the +) Sources: internal/re.js:111

Conclusion

Extracting components in node-semver is a multi-step process involving normalization, regex pattern matching, and type conversion. By centralizing this logic within the SemVer class, the library ensures that all derived information—whether a single integer via major() or a complex array via prerelease()—is consistent and compliant with the Semantic Versioning specification.