feat(validate): expose validate function with boolean return value (#38)

README.md

@@ -78,6 +78,16 @@ compareVersions.compare('10.1.1', '10.2.2', '<='); // return true
 compareVersions.compare('10.1.1', '10.2.2', '>='); // return false
 ```
 
+### Validate version numbers
+
+Applies the same ruleset as used before comparing version numbers and returns a boolean:
+
+```javascript
+compareVersions.validate('1.0.0-rc.1'); // return true
+compareVersions.validate('1.0-rc.1'); // return false
+compareVersions.validate('foo'); // return false
+```
+
 ### Browser
 
 If included directly in the browser, `compareVersions()` is available on the global window:

index.d.ts

@@ -37,6 +37,23 @@ declare const compareVersions: {
     secondVersion: string, 
     operator: compareVersions.CompareOperator
   ): boolean;
+
+  /**
+   * Validate [semver](https://semver.org/) version strings.
+   * 
+   * @param version Version number to validate
+   * @returns `true` if the version number is a valid semver version number, `false` otherwise.
+   *
+   * @example
+   * ```
+   * compareVersions.validate('1.0.0-rc.1'); // return true
+   * compareVersions.validate('1.0-rc.1'); // return false
+   * compareVersions.validate('foo'); // return false
+   * ```
+   */
+	validate(
+    version: string
+  ): boolean;
 };
 
 export = compareVersions;

index.js

@@ -97,6 +97,10 @@
     }
   }
 
+  compareVersions.validate = function(version) {
+    return typeof version === 'string' && semver.test(version);
+  }
+
   compareVersions.compare = function (v1, v2, operator) {
     // Validate operator
     validateOperator(operator);

test/validate.js

@@ -0,0 +1,29 @@
+const assert = require('assert');
+const compare = require('..');
+
+describe('validate versions', () => {
+  [
+    [undefined, false],
+    [null, false],
+    [42, false],
+    [{}, false],
+    [[], false],
+    [() => undefined, false],
+    ['6.3.', false],
+    ['1.2.3a', false],
+    ['1.2.-3a', false],
+    ['v1.0.0', true],
+    ['01.0.0', true],
+    ['1.0.x', true],
+    ['1.0.0-rc.1', true],
+    ['1.0.0-alpha', true],
+    ['1.0.0-build.3928', true],
+    ['1.0.0+20130313144700', true],
+    ['1.2.3.100', true],
+    ['2020', true]
+  ].forEach(([v, expected]) => {
+    it(`${v}`, () => {
+      assert.equal(compare.validate(v), expected)
+    });
+  });
+});