Add Number.isSafeInteger (#667)

microsoft · Dec 4, 2023 · 0885713 · 0885713
1 parent 9b3a698
commit 0885713
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Showing 3 changed files with 31 additions and 1 deletion.
diff --git a/jacdac-ts b/jacdac-ts
diff --git a/packages/runtime/src/main.ts b/packages/runtime/src/main.ts
@@ -273,4 +273,22 @@ describe("number", () => {
         checkNot(false)
         checkNot([NaN])
     })
+    test("isSafeInteger", () => {
+        const check = (v: unknown) => expect(Number.isSafeInteger(v)).toBe(true)
+        const checkNot = (v: unknown) =>
+            expect(Number.isSafeInteger(v)).toBe(false)
+
+        check(3)
+        check(3.0)
+        check(2 ** 53 - 1)
+        check(-(2 ** 53 - 1))
+
+        checkNot(2 ** 53)
+        checkNot(-(2 ** 53))
+        checkNot(NaN)
+        checkNot(Infinity)
+        checkNot(-Infinity)
+        checkNot("3")
+        checkNot(3.1)
+    })
 })
diff --git a/packages/runtime/src/number.ts b/packages/runtime/src/number.ts
@@ -20,4 +20,16 @@ export class Number {
     static isNaN(number: unknown): boolean {
         return isNaN(number as number)
     }
+    /**
+     * The boolean value true if the given value is a number that is a safe integer. Otherwise false.
+     * @param The value to be tested for being a safe integer.
+     */
+    static isSafeInteger(number: unknown): boolean {
+        return (
+            number >= -(2 ** 53 - 1) &&
+            number <= 2 ** 53 - 1 &&
+            typeof number === "number" &&
+            number === Math.round(number)
+        )
+    }
 }