refactor: use const, let

BREAKING CHANGES: `const`, `let` not supported in node < 6

Author: fent

README.md

@@ -11,8 +11,8 @@ A simple way to keep track of the speed of your readable streams.
 ```js
 const StreamSpeed = require('streamspeed');
 
-var rs = fs.createReadStream('somefile.avi');
-var ss = new StreamSpeed();
+let rs = fs.createReadStream('somefile.avi');
+let ss = new StreamSpeed();
 ss.add(rs);
 
 // Listen for events emitted by streamspeed on the given stream.
@@ -24,7 +24,7 @@ ss.on('speed', (speed, avgSpeed) => {
 Keep track of even a group of streams easily.
 
 ```js
-var group = new Streamspeed();
+let group = new Streamspeed();
 group.add(stream1);
 group.add(stream2);
 group.add(stream3);
@@ -65,8 +65,8 @@ StreamSpeed.toHuman(1024 * 1024 * 20.5, 's') => 20.5MB/s
 ```
 
 ### Event: 'speed'
-* `Number` - Speed at which streams in the group are being read.
-* `Number` - Average speed.
+* `number` - Speed at which streams in the group are being read.
+* `number` - Average speed.
 
 Will be emitted after the second time a stream is read and only if there is a change in speed.
 

lib/index.js

@@ -9,7 +9,7 @@ module.exports = class StreamSpeed extends EventEmitter {
    *
    * @constructor
    * @extends {EventEmitter}
-   * @param {Number} per The time unit speed will be measured in.
+   * @param {number} per The time unit speed will be measured in.
    */
   constructor(per) {
     super();
@@ -24,8 +24,8 @@ module.exports = class StreamSpeed extends EventEmitter {
    * Updates the group with the latest change in speed.
    *
    * @param {Object} meta
-   * @param {Number} speed
-   * @param {Number} avg
+   * @param {number} speed
+   * @param {number} avg
    */
   _update(meta, speed, avg) {
     meta.speed = speed;
@@ -62,38 +62,38 @@ module.exports = class StreamSpeed extends EventEmitter {
   /**
    * Add stream to group.
    *
-   * @param {Stream} stream
+   * @param {Readable} stream
    */
   add(origstream) {
     // Check if stream is already in group.
     if (this._streams.some(m => m.stream === origstream)) {
       throw Error('Stream already in group');
     }
-    
-    var onReadable = () => {
-      var data = stream.read();
+
+    const onReadable = () => {
+      const data = stream.read();
       if (data) {
         reader.update(data, onUpdate);
       }
     };
 
-    var cleanup = () => {
+    const cleanup = () => {
       stream.removeListener('readable', onReadable);
       stream.removeListener('end', cleanup);
       origstream.removeListener('error', cleanup);
       this._streams.splice(this._streams.indexOf(meta), 1);
     };
 
-    var meta = {
+    const meta = {
       stream  : origstream,
       speed   : 0,
       avg     : 0,
       cleanup,
     };
     this._streams.push(meta);
-    var reader = new Speedometer(this.per);
-    var stream = origstream.pipe(new PassThrough());
-    var onUpdate = this._update.bind(this, meta);
+    const reader = new Speedometer(this.per);
+    const stream = origstream.pipe(new PassThrough());
+    const onUpdate = this._update.bind(this, meta);
 
     stream.on('readable', onReadable);
     stream.on('end', cleanup);
@@ -108,14 +108,10 @@ module.exports = class StreamSpeed extends EventEmitter {
    */
   remove(stream) {
     // Check if stream is in group.
-    var meta;
-    if (!this._streams.some(function(m) {
-      meta = m;
-      return m.stream === stream;
-    })) {
+    const meta = this._streams.find(m => m.stream === stream);
+    if (!meta) {
       throw Error('Stream not found in group');
     }
-
     meta.cleanup();
   }
 
@@ -124,14 +120,14 @@ module.exports = class StreamSpeed extends EventEmitter {
    * Converts bytes to human readable unit.
    * Thank you Amir from StackOverflow.
    *
-   * @param {Number} bytes
-   * @return {String}
+   * @param {number} bytes
+   * @return {string}
    */
   static toHuman(bytes, timeUnit) {
-    var units = ' KMGTPEZYXWVU';
+    const units = ' KMGTPEZYXWVU';
     if (bytes <= 0) { return '0'; }
     timeUnit = timeUnit ? '/' + timeUnit : '';
-    var t2 = Math.min(Math.floor(Math.log(bytes) / Math.log(1024)), 12);
+    const t2 = Math.min(Math.floor(Math.log(bytes) / Math.log(1024)), 12);
     return (Math.round(bytes * 100 / Math.pow(1024, t2)) / 100) +
             units.charAt(t2).replace(' ', '') + 'B' + timeUnit;
   }

lib/speedometer.js

@@ -2,8 +2,8 @@ module.exports = class Speedometer {
   /**
    * Helps count the number of bytes per data event in streams.
    *
-   * @param {Number} per
    * @constructor
+   * @param {number} per
    */
   constructor(per) {
     this.per = per;
@@ -18,11 +18,11 @@ module.exports = class Speedometer {
   /**
    * Called when new data arrives.
    *
-   * @param {Buffer|String} data
+   * @param {Buffer|string} data
    * @param {Function} callback
    */
   update(data, callback) {
-    var now = Date.now();
+    const now = Date.now();
 
     // Check if this is the first data event.
     if (this.lasttime === null) {
@@ -31,15 +31,15 @@ module.exports = class Speedometer {
     }
 
     // Compare now to last time.
-    var speed = Math.round((data.length / (now - this.lasttime)) *
+    const speed = Math.round((data.length / (now - this.lasttime)) *
                          this.per);
     this.lasttime = now;
 
     // Get average speed.
     this.total += speed;
-    var avg = Math.round(this.total / ++this.iteration);
+    const avg = Math.round(this.total / ++this.iteration);
 
-    var change = this.speed !== speed || this.avg !== avg;
+    const change = this.speed !== speed || this.avg !== avg;
     this.speed = speed;
     this.avg = avg;
 

package.json

@@ -27,7 +27,7 @@
     "sinon": "^6.0.0"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=6"
   },
   "license": "MIT"
 }

test/group-test.js

@@ -5,16 +5,16 @@ const sinon       = require('sinon');
 
 
 describe('Create a group and write to it', () => {
-  var group = new StreamSpeed();
-  var s1 = new MockStream();
-  var s2 = new MockStream();
-  var s3 = new MockStream();
+  const group = new StreamSpeed();
+  const s1 = new MockStream();
+  const s2 = new MockStream();
+  const s3 = new MockStream();
 
   group.add(s1);
   group.add(s2);
   group.add(s3);
 
-  var spy = sinon.spy();
+  const spy = sinon.spy();
   group.on('speed', spy);
 
   it('All streams added show up', () => {
@@ -30,11 +30,9 @@ describe('Create a group and write to it', () => {
   });
 
   it('Should emit `speed` event once for each stream', (done) => {
-    // read at 500 B/s on 2 streams, so 1000 B/s.
+    // Read at 500 B/s on 2 streams, 1000 B/s in total.
     s1.interval(100, 6, 200, true, true);
     s2.interval(100, 6, 200, true);
-    setTimeout(() => {
-    }, 1200);
     s2.on('finish', () => {
       assert.ok(spy.firstCall.calledWith(500, 500));
       assert.ok(spy.secondCall.calledWith(1000, 1000));

test/mockstream.js

@@ -1,7 +1,7 @@
 const PassThrough = require('stream').PassThrough;
 const sinon       = require('sinon');
 
-var clock;
+let clock;
 before(() => { clock = sinon.useFakeTimers(); });
 after(() => { clock.restore(); });
 
@@ -21,17 +21,17 @@ module.exports = class Mock extends PassThrough {
   /**
    * Runs the function run n times every interval.
    *
-   * @param {Number} length
-   * @param {Number} n
-   * @param {Number} interval
-   * @param {Boolean} end
-   * @param {Boolean} skipTick
+   * @param {number} length
+   * @param {number} n
+   * @param {number} interval
+   * @param {boolean} end
+   * @param {boolean} skipTick
    */
   interval(length, n, interval, end, skipTick) {
-    var callback = this.end.bind(this);
-    var i = 0;
+    const callback = this.end.bind(this);
+    let i = 0;
 
-    var iid = setInterval(() => {
+    const iid = setInterval(() => {
       this.write(Buffer.alloc(length));
       if (++i === n) {
         clearInterval(iid);

test/remove-test.js

@@ -6,13 +6,13 @@ const sinon       = require('sinon');
 
 
 describe('Immediately remove a stream', () => {
-  var ss = new StreamSpeed();
-  var s = new PassThrough();
+  const ss = new StreamSpeed();
+  const s = new PassThrough();
   ss.add(s);
   ss.remove(s);
 
   // Listen for things.
-  var spy = sinon.spy();
+  const spy = sinon.spy();
   s.on('speed', spy);
 
   it('Does not emit any events', (done) => {
@@ -31,17 +31,16 @@ describe('Immediately remove a stream', () => {
 
 
 describe('Unwatch after several writes', () => {
-  var ss = new StreamSpeed(1);
-  var s = new MockStream();
+  const ss = new StreamSpeed(1);
+  const s = new MockStream();
   ss.add(s);
 
-  var spy = sinon.spy();
+  const spy = sinon.spy();
   ss.on('speed', spy);
 
   it('Emits no events after calling remove', (done) => {
     // Write at 1 bps for 0.5 seconds.
     s.interval(100, 5, 100, true);
-
     s.on('finish', done);
   });
 

test/single-test.js

@@ -7,11 +7,11 @@ const sinon       = require('sinon');
 
 describe('Read from a stream', () => {
   describe('with a unit', () => {
-    var ss = new StreamSpeed(1);
-    var rs = new MockStream();
+    const ss = new StreamSpeed(1);
+    const rs = new MockStream();
     ss.add(rs);
 
-    var spy = sinon.spy();
+    const spy = sinon.spy();
     ss.on('speed', spy);
 
     it('Emitted one speed event', (done) => {
@@ -32,11 +32,11 @@ describe('Read from a stream', () => {
   });
 
   describe('with no unit', () => {
-    var ss = new StreamSpeed();
-    var rs = new MockStream();
+    const ss = new StreamSpeed();
+    const rs = new MockStream();
     ss.add(rs);
 
-    var spy = sinon.spy();
+    const spy = sinon.spy();
     ss.on('speed', spy);
 
     it('Emited one speed event', (done) => {
@@ -55,11 +55,11 @@ describe('Read from a stream', () => {
   });
 
   describe('Written to at the rate of the unit', () => {
-    var ss = new StreamSpeed(100);
-    var rs = new MockStream();
+    const ss = new StreamSpeed(100);
+    const rs = new MockStream();
     ss.add(rs);
 
-    var spy = sinon.spy();
+    const spy = sinon.spy();
     ss.on('speed', spy);
 
     it('Speed and avg speed are constant', (done) => {
@@ -74,11 +74,11 @@ describe('Read from a stream', () => {
 });
 
 describe('Read when stream speed is sporadic', () => {
-  var ss = new StreamSpeed();
-  var rs = new MockStream();
+  const ss = new StreamSpeed();
+  const rs = new MockStream();
   ss.add(rs);
 
-  var spy = sinon.spy();
+  const spy = sinon.spy();
   ss.on('speed', spy);
 
   it('Speed and avg speed changes', () => {
@@ -95,11 +95,11 @@ describe('Read when stream speed is sporadic', () => {
 
 describe('Stream being monitored has an error', () => {
   it('Stream gets removed', () => {
-    var ss = new StreamSpeed();
-    var rs = new PassThrough();
+    const ss = new StreamSpeed();
+    const rs = new PassThrough();
     rs.on('error', () => {});
     ss.add(rs);
-    rs.emit('error', new Error('my error'));
+    rs.emit('error', Error('my error'));
     assert.equal(ss.getStreams().length, 0);
   });
 });