Implement Timestamp.valueOf().

This enables comparison of Timestamp objects using the arithmetic comparison operators, such as < and >. #2632
firebase · Feb 21, 2020 · 53894ae · 53894ae
1 parent fbe0543
commit 53894ae
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diff --git a/packages/firestore/src/api/timestamp.ts b/packages/firestore/src/api/timestamp.ts
@@ -89,4 +89,31 @@ export class Timestamp {
       ')'
     );
   }
+
+  // Overriding valueOf() allows Timestamp objects to be compared in JavaScript using the
+  // arithmetic comparison operators, such as < and >.
+  // https://github.com/firebase/firebase-js-sdk/issues/2632
+  valueOf(): string {
+    const formattedSeconds = Timestamp.normalizeAndPad(
+      this.seconds,
+      Timestamp.MIN_SECONDS,
+      Timestamp.MAX_SECONDS
+    );
+    const formattedNanoseconds = Timestamp.normalizeAndPad(
+      this.nanoseconds,
+      Timestamp.MIN_NANOSECONDS,
+      Timestamp.MAX_NANOSECONDS
+    );
+    return formattedSeconds + '.' + formattedNanoseconds;
+  }
+
+  private static normalizeAndPad(
+    value: number,
+    minValue: number,
+    maxValue: number
+  ): string {
+    const padLength = Math.ceil(Math.log10(maxValue - minValue));
+    const normalizedValue = value - minValue;
+    return normalizedValue.toString().padStart(padLength, '0');
+  }
 }
diff --git a/packages/firestore/test/unit/api/timestamp.test.ts b/packages/firestore/test/unit/api/timestamp.test.ts
@@ -76,4 +76,16 @@ describe('Timestamp', () => {
       nanoseconds: 750000000
     });
   });
+
+  it('valueOf', () => {
+    expect(new Timestamp(-62135596677, 456).valueOf()).to.equal(
+      '000000000123.000000456'
+    );
+    expect(new Timestamp(-62135596800, 0).valueOf()).to.equal(
+      '000000000000.000000000'
+    );
+    expect(new Timestamp(253402300799, 1e9 - 1).valueOf()).to.equal(
+      '315537897599.999999999'
+    );
+  });
 });