feat(difference): add amDifference pipe

README.md

@@ -115,6 +115,21 @@ import {DurationPipe} from 'angular2-moment';
 
 Prints `Uptime: 6 minutes`
 
+## amDifference pipe
+
+``` typescript
+import {DifferencePipe} from 'angular2-moment';
+
+@Component({
+  selector: 'app',
+  pipes: [DifferencePipe],
+  template: `
+    Expiration: <time>{{nextDay | amDifference: today :'days' : true}}</time> days
+  `
+})
+```
+Prints `Expiration: 1 day`
+
 Complete Example
 ----------------
 

src/DifferencePipe.spec.ts

@@ -0,0 +1,41 @@
+import {DifferencePipe} from './DifferencePipe';
+import * as moment from 'moment';
+
+describe('DifferencePipe', () => {
+  var pipe: DifferencePipe;
+
+  beforeEach(() => pipe = new DifferencePipe());
+
+  describe('#transform', () => {
+
+    it('should take the difference of two dates in milliseconds', () => {
+      let today = new Date(2012, 0, 22, 0, 0, 0);
+      let testDate = new Date(today.getFullYear(), today.getMonth(), today.getDate(), 13, 33, 33);
+      expect(pipe.transform(testDate, today)).toBe(48813000);
+    });
+
+    it('should support passing "years", "months", "days", etc as a units parameter', () => {
+      let test = new Date(2012, 0, 22, 4, 46, 54);
+      let testDate1 = new Date(2013, 0, 22, 4, 46, 54);
+      expect(pipe.transform(testDate1, test, 'years')).toBe(1);
+      let testDate2 = new Date(2012, 1, 22, 4, 46, 54);
+      expect(pipe.transform(testDate2, test, 'months')).toBe(1);
+      let testDate3 = new Date(2012, 0, 23, 4, 46, 54);
+      expect(pipe.transform(testDate3, test, 'days')).toBe(1);
+    });
+
+    it('should allow rounding to be disabled via parameter', () => {
+      let test = new Date(2012, 0, 22, 4, 46, 54);
+      let testDate1 = new Date(test.getFullYear() + 1, test.getMonth() + 6, test.getDate());
+      expect(pipe.transform(testDate1, test, 'years')).toBe(1);
+      expect(pipe.transform(testDate1, test, 'years', true)).toBeCloseTo(1.5, 1);
+    });
+
+    it('dates from the future should return negative values', () => {
+      let today = new Date(2012, 0, 22, 4, 46, 54);
+      let testDate = new Date(2013, 0, 22, 4, 46, 54);
+      expect(String(pipe.transform(today, testDate))).toContain('-');
+    });
+
+  });
+});

src/DifferencePipe.ts

@@ -0,0 +1,18 @@
+/* angular2-moment (c) 2015, 2016 Uri Shaked / MIT Licence */
+
+import {Pipe, ChangeDetectorRef, PipeTransform} from '@angular/core';
+import * as moment from 'moment';
+
+// under systemjs, moment is actually exported as the default export, so we account for that
+const momentConstructor: (value?: any) => moment.Moment = (<any>moment).default || moment;
+
+@Pipe({ name: 'amDifference', pure: false })
+export class DifferencePipe implements PipeTransform {
+  transform(value: Date | moment.Moment, otherValue: Date | moment.Moment, unit?: string, precision?: boolean): number {
+
+    let date = momentConstructor(value);
+    let date2 = (otherValue !== null) ? momentConstructor(otherValue) : momentConstructor();
+
+    return date.diff(date2, unit, precision);
+  }
+}

src/index.ts

@@ -3,3 +3,4 @@ export * from './DateFormatPipe';
 export * from './DurationPipe';
 export * from './FromUnixPipe';
 export * from './TimeAgoPipe';
+export * from './DifferencePipe';