fix: Buffer.from(<string>) requires nodejs 4.5+ (#2)

Add version detection and use deprecated `new Buffer(<string>)`, if the
new Buffer API isn't supported by runtime.

See nodejs/node#7562.

index.js

@@ -5,8 +5,11 @@ var crypto = require('crypto');
 var path = require('path');
 var through = require('through2');
 var cheerio = require('cheerio');
+var semver = require('semver');
 var PluginError = require('gulp-util').PluginError;
 
+var NODE_VERSION_WITH_NEW_BUFFER_API = '4.5.0';
+var useDeprecatedBufferApi = semver.lt(process.version, NODE_VERSION_WITH_NEW_BUFFER_API);
 var PLUGIN_NAME = 'gulp-sri-hash';
 var DEFAULT_ALGO = 'sha384';
 var DEFAULT_SELECTOR = 'link[href][rel=stylesheet]:not([integrity]), script[src]:not([integrity])';
@@ -16,6 +19,14 @@ var cache;
 module.exports = gulpSriHashPlugin;
 module.exports.PLUGIN_NAME = PLUGIN_NAME;
 
+function makeBufferFromString(string) {
+ if (useDeprecatedBufferApi) {
+ return new Buffer(string);
+ }
+
+ return Buffer.from(string);
+}
+
 function normalizePath(node, config) {
  var src = node.name == 'script' ? node.attribs.src : node.attribs.href;
 
@@ -51,9 +62,8 @@ function resolveAbsolutePath(file, localPath) {
 
 function calculateSri(fullPath, algorithm) {
  var file = fs.readFileSync(fullPath);
- var digest = crypto.createHash(algorithm).update(file).digest();
 
- return Buffer.from(digest).toString('base64');
+ return crypto.createHash(algorithm).update(file).digest('base64');
 }
 
 function getFileHash(fullPath, algorithm) {
@@ -73,7 +83,7 @@ function updateDOM(file, config) {
 
  if ($candidates.length > 0) {
  $candidates.each(addIntegrityAttribute);
- file.contents = Buffer.from($.html());
+ file.contents = makeBufferFromString($.html());
  }
 
  return file;

package.json

@@ -29,6 +29,7 @@
  "cheerio": "^0.22.0",
  "gulp": "^3.9.1",
  "gulp-util": "^3.0.7",
+ "semver": "^5.3.0",
  "through2": "^2.0.1"
  },
  "engines": {