Add full support for negative numbers (#104)

index.js

@@ -111,16 +111,17 @@ function parse(str) {
  */
 
 function fmtShort(ms) {
-  if (ms >= d) {
+  var msAbs = Math.abs(ms);
+  if (msAbs >= d) {
     return Math.round(ms / d) + 'd';
   }
-  if (ms >= h) {
+  if (msAbs >= h) {
     return Math.round(ms / h) + 'h';
   }
-  if (ms >= m) {
+  if (msAbs >= m) {
     return Math.round(ms / m) + 'm';
   }
-  if (ms >= s) {
+  if (msAbs >= s) {
     return Math.round(ms / s) + 's';
   }
   return ms + 'ms';
@@ -135,25 +136,27 @@ function fmtShort(ms) {
  */
 
 function fmtLong(ms) {
-  return (
-    plural(ms, d, 'day') ||
-    plural(ms, h, 'hour') ||
-    plural(ms, m, 'minute') ||
-    plural(ms, s, 'second') ||
-    ms + ' ms'
-  );
+  var msAbs = Math.abs(ms);
+  if (msAbs >= d) {
+    return plural(ms, msAbs, d, 'day');
+  }
+  if (msAbs >= h) {
+    return plural(ms, msAbs, h, 'hour');
+  }
+  if (msAbs >= m) {
+    return plural(ms, msAbs, m, 'minute');
+  }
+  if (msAbs >= s) {
+    return plural(ms, msAbs, s, 'second');
+  }
+  return ms + ' ms';
 }
 
 /**
  * Pluralization helper.
  */
 
-function plural(ms, n, name) {
-  if (ms < n) {
-    return;
-  }
-  if (ms < n * 1.5) {
-    return Math.floor(ms / n) + ' ' + name;
-  }
-  return Math.ceil(ms / n) + ' ' + name + 's';
+function plural(ms, msAbs, n, name) {
+  var isPlural = msAbs >= n * 1.5;
+  return Math.round(ms / n) + ' ' + name + (isPlural ? 's' : '');
 }

readme.md

@@ -17,13 +17,17 @@ ms('1m')      // 60000
 ms('5s')      // 5000
 ms('1y')      // 31557600000
 ms('100')     // 100
+ms('-3 days') // -259200000
+ms('-1h')     // -3600000
+ms('-200')    // -200
 ```
 
 ### Convert from Milliseconds
 
 ```js
 ms(60000)             // "1m"
 ms(2 * 60000)         // "2m"
+ms(-3 * 60000)        // "-3m"
 ms(ms('10 hours'))    // "10h"
 ```
 
@@ -32,6 +36,7 @@ ms(ms('10 hours'))    // "10h"
 ```js
 ms(60000, { long: true })             // "1 minute"
 ms(2 * 60000, { long: true })         // "2 minutes"
+ms(-3 * 60000, { long: true })        // "-3 minutes"
 ms(ms('10 hours'), { long: true })    // "10 hours"
 ```
 

tests.js

@@ -65,10 +65,16 @@ describe('ms(string)', function() {
     expect(ms('.5ms')).to.be(0.5);
   });
 
-  it('should work with numbers starting with -', function() {
-    expect(ms('-5')).to.be(-5);
-    expect(ms('-.5ms')).to.be(-0.5);
-    expect(ms('-0.5ms')).to.be(-0.5);
+  it('should work with negative integers', function() {
+    expect(ms('-100ms')).to.be(-100);
+  });
+
+  it('should work with negative decimals', function() {
+    expect(ms('-1.5h')).to.be(-5400000);
+  });
+
+  it('should work with negative decimals starting with "."', function() {
+    expect(ms('-.5h')).to.be(-1800000);
   });
 });
 
@@ -108,6 +114,18 @@ describe('ms(long string)', function() {
   it('should work with decimals', function() {
     expect(ms('1.5 hours')).to.be(5400000);
   });
+
+  it('should work with negative integers', function() {
+    expect(ms('-100 milliseconds')).to.be(-100);
+  });
+
+  it('should work with negative decimals', function() {
+    expect(ms('-1.5 hours')).to.be(-5400000);
+  });
+
+  it('should work with negative decimals starting with "."', function() {
+    expect(ms('-.5 hr')).to.be(-1800000);
+  });
 });
 
 // numbers
@@ -121,34 +139,54 @@ describe('ms(number, { long: true })', function() {
 
   it('should support milliseconds', function() {
     expect(ms(500, { long: true })).to.be('500 ms');
+
+    expect(ms(-500, { long: true })).to.be('-500 ms');
   });
 
   it('should support seconds', function() {
     expect(ms(1000, { long: true })).to.be('1 second');
     expect(ms(1200, { long: true })).to.be('1 second');
     expect(ms(10000, { long: true })).to.be('10 seconds');
+
+    expect(ms(-1000, { long: true })).to.be('-1 second');
+    expect(ms(-1200, { long: true })).to.be('-1 second');
+    expect(ms(-10000, { long: true })).to.be('-10 seconds');
   });
 
   it('should support minutes', function() {
     expect(ms(60 * 1000, { long: true })).to.be('1 minute');
     expect(ms(60 * 1200, { long: true })).to.be('1 minute');
     expect(ms(60 * 10000, { long: true })).to.be('10 minutes');
+
+    expect(ms(-1 * 60 * 1000, { long: true })).to.be('-1 minute');
+    expect(ms(-1 * 60 * 1200, { long: true })).to.be('-1 minute');
+    expect(ms(-1 * 60 * 10000, { long: true })).to.be('-10 minutes');
   });
 
   it('should support hours', function() {
     expect(ms(60 * 60 * 1000, { long: true })).to.be('1 hour');
     expect(ms(60 * 60 * 1200, { long: true })).to.be('1 hour');
     expect(ms(60 * 60 * 10000, { long: true })).to.be('10 hours');
+
+    expect(ms(-1 * 60 * 60 * 1000, { long: true })).to.be('-1 hour');
+    expect(ms(-1 * 60 * 60 * 1200, { long: true })).to.be('-1 hour');
+    expect(ms(-1 * 60 * 60 * 10000, { long: true })).to.be('-10 hours');
   });
 
   it('should support days', function() {
     expect(ms(24 * 60 * 60 * 1000, { long: true })).to.be('1 day');
     expect(ms(24 * 60 * 60 * 1200, { long: true })).to.be('1 day');
     expect(ms(24 * 60 * 60 * 10000, { long: true })).to.be('10 days');
+
+    expect(ms(-1 * 24 * 60 * 60 * 1000, { long: true })).to.be('-1 day');
+    expect(ms(-1 * 24 * 60 * 60 * 1200, { long: true })).to.be('-1 day');
+    expect(ms(-1 * 24 * 60 * 60 * 10000, { long: true })).to.be('-10 days');
   });
 
   it('should round', function() {
     expect(ms(234234234, { long: true })).to.be('3 days');
+
+    expect(ms(-234234234, { long: true })).to.be('-3 days');
   });
 });
 
@@ -163,30 +201,46 @@ describe('ms(number)', function() {
 
   it('should support milliseconds', function() {
     expect(ms(500)).to.be('500ms');
+
+    expect(ms(-500)).to.be('-500ms');
   });
 
   it('should support seconds', function() {
     expect(ms(1000)).to.be('1s');
     expect(ms(10000)).to.be('10s');
+
+    expect(ms(-1000)).to.be('-1s');
+    expect(ms(-10000)).to.be('-10s');
   });
 
   it('should support minutes', function() {
     expect(ms(60 * 1000)).to.be('1m');
     expect(ms(60 * 10000)).to.be('10m');
+
+    expect(ms(-1 * 60 * 1000)).to.be('-1m');
+    expect(ms(-1 * 60 * 10000)).to.be('-10m');
   });
 
   it('should support hours', function() {
     expect(ms(60 * 60 * 1000)).to.be('1h');
     expect(ms(60 * 60 * 10000)).to.be('10h');
+
+    expect(ms(-1 * 60 * 60 * 1000)).to.be('-1h');
+    expect(ms(-1 * 60 * 60 * 10000)).to.be('-10h');
   });
 
   it('should support days', function() {
     expect(ms(24 * 60 * 60 * 1000)).to.be('1d');
     expect(ms(24 * 60 * 60 * 10000)).to.be('10d');
+
+    expect(ms(-1 * 24 * 60 * 60 * 1000)).to.be('-1d');
+    expect(ms(-1 * 24 * 60 * 60 * 10000)).to.be('-10d');
   });
 
   it('should round', function() {
     expect(ms(234234234)).to.be('3d');
+
+    expect(ms(-234234234)).to.be('-3d');
   });
 });