feat: add jsonReviver option for parsing

CLOSES #35

index.d.ts

@@ -41,6 +41,8 @@ declare module 'gulp-merge-json' {
     mergeArrays?: boolean;
     /** Custom merge function for use with mergeWith */
     customizer?: (objValue: obj, srcValue: obj, key?: string, object?: obj, source?: obj, stack?: any) => any;
+    /** Custom JSON reviver function passed to parse */
+    jsonReviver?: (key: string, value: any) => any;
     /** Custom JSON replacer function passed to stringify */
     jsonReplacer?: (key: string, value: any) => any;
     /**

index.js

@@ -51,6 +51,7 @@ module.exports = function mergeJson(opts) {
     mergeArrays: true,
     customizer: null,
     jsonReplacer: null,
+    jsonReviver: null,
     jsonSpace: '\t',
     json5: false,
     ...opts,
@@ -81,7 +82,7 @@ module.exports = function mergeJson(opts) {
     }
 
     try {
-      parsed = jsonLib.parse(file.contents.toString('utf8'));
+      parsed = jsonLib.parse(file.contents.toString('utf8'), options.jsonReviver);
     } catch (err) {
       err.message = `Error while parsing ${file.path}: ${err.message}`;
       return this.emit('error', new PluginError(PLUGIN_NAME, err));

test/index.test.js

@@ -289,6 +289,25 @@ describe('gulp-merge-json', () => {
     stream.end();
   });
 
+  test('uses jsonReviver when parsing if supplied in options', (done) => {
+    const stream = gulp.src(['test/json/test1.json', 'test/json/test2.json']).pipe(merge({
+      jsonReviver: (key, value) => {
+        if (key === 'pet') {
+          return undefined;
+        }
+
+        return value;
+      },
+    }));
+
+    stream.on('data', (file) => {
+      const expected = ['{', '\t"name": "Josh",', '\t"tags": [', '\t\t"awesome",', '\t\t"fun"', '\t],', '\t"place": "San Francisco",', '\t"settings": {', '\t\t"likesSleep": true', '\t}', '}'].join('\n');
+
+      expect(file.contents.toString()).toBe(expected);
+      done();
+    });
+  });
+
   test('uses jsonReplacer when stringifying if supplied in options', (done) => {
     const stream = gulp.src(['test/json/test1.json', 'test/json/test2.json']).pipe(merge({
       jsonReplacer: (key, value) => {