validate-npm-package-license

Give me a string and I'll tell you if it's a valid npm package license string.

1var valid = require('validate-npm-package-license');

SPDX license identifiers are valid license strings:

1
2var assert = require('assert');
3var validSPDXExpression = {
4  validForNewPackages: true,
5  validForOldPackages: true,
6  spdx: true
7};
8
9assert.deepEqual(valid('MIT'), validSPDXExpression);
10assert.deepEqual(valid('BSD-2-Clause'), validSPDXExpression);
11assert.deepEqual(valid('Apache-2.0'), validSPDXExpression);
12assert.deepEqual(valid('ISC'), validSPDXExpression);

The function will return a warning and suggestion for nearly-correct license identifiers:

1assert.deepEqual(
2  valid('Apache 2.0'),
3  {
4    validForOldPackages: false,
5    validForNewPackages: false,
6    warnings: [
7      'license should be ' +
8      'a valid SPDX license expression (without "LicenseRef"), ' +
9      '"UNLICENSED", or ' +
10      '"SEE LICENSE IN <filename>"',
11      'license is similar to the valid expression "Apache-2.0"'
12    ]
13  }
14);

SPDX expressions are valid, too ...

1// Simple SPDX license expression for dual licensing
2assert.deepEqual(
3  valid('(GPL-3.0-only OR BSD-2-Clause)'),
4  validSPDXExpression
5);

... except if they contain LicenseRef:

1var warningAboutLicenseRef = {
2  validForOldPackages: false,
3  validForNewPackages: false,
4  spdx: true,
5  warnings: [
6    'license should be ' +
7    'a valid SPDX license expression (without "LicenseRef"), ' +
8    '"UNLICENSED", or ' +
9    '"SEE LICENSE IN <filename>"',
10  ]
11};
12
13assert.deepEqual(
14  valid('LicenseRef-Made-Up'),
15  warningAboutLicenseRef
16);
17
18assert.deepEqual(
19  valid('(MIT OR LicenseRef-Made-Up)'),
20  warningAboutLicenseRef
21);

If you can't describe your licensing terms with standardized SPDX identifiers, put the terms in a file in the package and point users there:

1assert.deepEqual(
2  valid('SEE LICENSE IN LICENSE.txt'),
3  {
4    validForNewPackages: true,
5    validForOldPackages: true,
6    inFile: 'LICENSE.txt'
7  }
8);
9
10assert.deepEqual(
11  valid('SEE LICENSE IN license.md'),
12  {
13    validForNewPackages: true,
14    validForOldPackages: true,
15    inFile: 'license.md'
16  }
17);

If there aren't any licensing terms, use UNLICENSED:

1var unlicensed = {
2  validForNewPackages: true,
3  validForOldPackages: true,
4  unlicensed: true
5};
6assert.deepEqual(valid('UNLICENSED'), unlicensed);
7assert.deepEqual(valid('UNLICENCED'), unlicensed);