New: Add events option

Author: c-vetter

README.md

@@ -96,6 +96,14 @@ Type: `Boolean`
 
 Default: `true`
 
+##### `options.events`
+
+An event name or array of event names to listen for. Useful if you only need to watch specific events.
+
+Type: `String | Array<String>`
+
+Default: `[ 'add', 'change', 'unlink' ]`
+
 ##### other
 
 Options are passed directly to [lodash.debounce][lodash-debounce] and [chokidar][chokidar], so all their options are supported. Any debounce-related options are documented in [lodash.debounce][lodash-debounce]. Any chokidar-related options are documented in [chokidar][chokidar].

index.js

@@ -10,8 +10,9 @@ function assignNullish(objValue, srcValue) {
 }
 
 var defaults = {
-  ignoreInitial: true,
   delay: 200,
+  events: ['add', 'change', 'unlink'],
+  ignoreInitial: true,
   queue: true,
 };
 
@@ -23,6 +24,10 @@ function watch(glob, options, cb) {
 
   var opt = assignWith({}, defaults, options, assignNullish);
 
+  if (!Array.isArray(opt.events)) {
+    opt.events = [opt.events];
+  }
+
   var queued = false;
   var running = false;
 
@@ -54,12 +59,17 @@ function watch(glob, options, cb) {
     asyncDone(cb, runComplete);
   }
 
+  var fn;
   if (typeof cb === 'function') {
-    var fn = debounce(onChange, opt.delay, opt);
-    watcher
-      .on('change', fn)
-      .on('unlink', fn)
-      .on('add', fn);
+    fn = debounce(onChange, opt.delay, opt);
+  }
+
+  function watchEvent(eventName) {
+    watcher.on(eventName, fn);
+  }
+
+  if (fn) {
+    opt.events.forEach(watchEvent);
   }
 
   return watcher;

test/index.js

@@ -42,6 +42,10 @@ describe('glob-watcher', function() {
     return del(outDir);
   });
 
+  after(function() {
+    return del(outDir);
+  });
+
   it('only requires a glob and returns watcher', function(done) {
     watcher = watch(outGlob);
 
@@ -248,4 +252,30 @@ describe('glob-watcher', function() {
     // So wait for `on('ready')`
     watcher.on('ready', changeFile);
   });
+
+  it('watches exactly the given event', function(done) {
+    var spy = expect.createSpy()
+    .andCall(function(cb) {
+      cb();
+      spy.andThrow(new Error('`Add` handler called for `change` event'));
+      setTimeout(done, 500);
+      changeFile();
+    });
+
+    watcher = watch(outGlob, { events: 'add' }, spy);
+
+    watcher.on('ready', addFile);
+  });
+
+  it('accepts multiple events to watch', function(done) {
+    var spy = expect.createSpy()
+    .andThrow(new Error('`Add`/`Unlink` handler called for `change` event'));
+
+    watcher = watch(outGlob, { events: ['add', 'unlink'] }, spy);
+
+    watcher.on('ready', function() {
+      changeFile();
+      setTimeout(done, 500);
+    });
+  });
 });