Allow removing the zeroes of durations

src/duration.js

@@ -488,21 +488,25 @@ export default class Duration {
    * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat/NumberFormat#options
    * @param {Object} opts - Formatting options. Accepts the same keys as the options parameter of the native `Intl.NumberFormat` constructor, as well as `listStyle`.
    * @param {string} [opts.listStyle='narrow'] - How to format the merged list. Corresponds to the `style` property of the options parameter of the native `Intl.ListFormat` constructor.
+   * @param {boolean} [opts.showZeros=true] - Show all units previously used by the duration even if they are zero
    * @example
    * ```js
-   * var dur = Duration.fromObject({ days: 1, hours: 5, minutes: 6 })
-   * dur.toHuman() //=> '1 day, 5 hours, 6 minutes'
-   * dur.toHuman({ listStyle: "long" }) //=> '1 day, 5 hours, and 6 minutes'
-   * dur.toHuman({ unitDisplay: "short" }) //=> '1 day, 5 hr, 6 min'
+   * var dur = Duration.fromObject({ months: 1, weeks: 0, hours: 5, minutes: 6 })
+   * dur.toHuman() //=> '1 month, 0 weeks, 5 hours, 6 minutes'
+   * dur.toHuman({ listStyle: "long" }) //=> '1 month, 0 weeks, 5 hours, and 6 minutes'
+   * dur.toHuman({ unitDisplay: "short" }) //=> '1 mth, 0 wks, 5 hr, 6 min'
+   * dur.toHuman({ showZeros: false }) //=> '1 month, 5 hours, 6 minutes'
    * ```
    */
   toHuman(opts = {}) {
     if (!this.isValid) return INVALID;
 
+    const showZeros = opts.showZeros !== false;
+
     const l = orderedUnits
       .map((unit) => {
         const val = this.values[unit];
-        if (isUndefined(val)) {
+        if (isUndefined(val) || (val === 0 && !showZeros)) {
           return null;
         }
         return this.loc
@@ -862,6 +866,17 @@ export default class Duration {
     return clone(this, { values: negated }, true);
   }
 
+  /**
+   * Removes all units with values equal to 0 from this Duration.
+   * @example Duration.fromObject({ years: 2, days: 0, hours: 0, minutes: 0 }).removeZeros().toObject() //=> { years: 2 }
+   * @return {Duration}
+   */
+  removeZeros() {
+    if (!this.isValid) return this;
+    const vals = removeZeroes(this.values);
+    return clone(this, { values: vals }, true);
+  }
+
   /**
    * Get the years.
    * @type {number}

test/duration/format.test.js

@@ -309,6 +309,36 @@ test("Duration#toHuman accepts number format opts", () => {
   );
 });
 
+test("Duration#toHuman accepts hiding of zero values", () => {
+  expect(
+    Duration.fromObject({
+      years: 1,
+      months: 0,
+      weeks: 1,
+      days: 0,
+      hours: 4,
+      minutes: 0,
+      seconds: 6,
+      milliseconds: 0,
+    }).toHuman({ showZeros: false })
+  ).toEqual("1 year, 1 week, 4 hours, 6 seconds");
+});
+
+test("Duration#toHuman handles undefined showZeros", () => {
+  expect(
+    Duration.fromObject({
+      years: 1,
+      months: 0,
+      weeks: 1,
+      days: 0,
+      hours: 4,
+      minutes: 0,
+      seconds: 6,
+      milliseconds: 0,
+    }).toHuman({ showZeros: undefined })
+  ).toEqual("1 year, 0 months, 1 week, 0 days, 4 hours, 0 minutes, 6 seconds, 0 milliseconds");
+});
+
 test("Duration#toHuman works in differt languages", () => {
   expect(dur().reconfigure({ locale: "fr" }).toHuman()).toEqual(
     "1 an, 2 mois, 1 semaine, 3 jours, 4 heures, 5 minutes, 6 secondes, 7 millisecondes"

test/duration/units.test.js

@@ -359,3 +359,53 @@ test("Duration#valueOf value of the duration with lower and higher order units",
   const dur = Duration.fromObject({ days: 2, seconds: 1 });
   expect(dur.valueOf()).toBe(172801000);
 });
+
+//------
+// #removeZeroes()
+//-------
+
+test("Duration#removeZeros leaves empty object if everything was zero", () => {
+  expect(Duration.fromObject({ years: 0, days: 0, hours: 0 }).removeZeros().toObject()).toEqual({});
+});
+
+test("Duration#removeZeros removes units with zero value", () => {
+  expect(
+    Duration.fromObject({
+      years: 1,
+      months: 0,
+      weeks: 1,
+      days: 0,
+      hours: 4,
+      minutes: 0,
+      seconds: 6,
+      milliseconds: 0,
+    })
+      .removeZeros()
+      .toObject()
+  ).toEqual({
+    years: 1,
+    weeks: 1,
+    hours: 4,
+    seconds: 6,
+  });
+});
+
+test("Duration#removeZeros removes nothing if no value is zero", () => {
+  const dur = {
+    years: 1,
+    months: 2,
+    weeks: 1,
+    days: 3,
+    hours: 4,
+    minutes: 5,
+    seconds: 6,
+    milliseconds: 7,
+  };
+  expect(Duration.fromObject(dur).removeZeros().toObject()).toEqual(dur);
+});
+
+test("Duration#removeZeros maintains invalidity", () => {
+  const dur = Duration.invalid("because").removeZeros();
+  expect(dur.isValid).toBe(false);
+  expect(dur.invalidReason).toBe("because");
+});