Make Fraction's booleanish methods work with NaN

ref #11
xenharmonic-devs · Dec 9, 2023 · 7c850ba · 7c850ba
1 parent fb0e7fa
commit 7c850ba
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diff --git a/src/__tests__/fraction.spec.ts b/src/__tests__/fraction.spec.ts
@@ -191,4 +191,34 @@ describe('Fraction', () => {
     const fraction = new Fraction(5, 11);
     expect(fraction.toString()).toBe("0.'45'");
   });
+
+  it('is not equal to NaN', () => {
+    const fraction = new Fraction(3, 2);
+    expect(fraction.equals(NaN)).toBe(false);
+  });
+
+  it('is not equal to garbage', () => {
+    const fraction = new Fraction(3, 2);
+    expect(fraction.equals('asdf')).toBe(false);
+  });
+
+  it("doesn't compare to NaN", () => {
+    const fraction = new Fraction(7, 3);
+    expect(fraction.compare(NaN)).toBeNaN();
+  });
+
+  it("doesn't compare to garbage", () => {
+    const fraction = new Fraction(7, 3);
+    expect(fraction.compare('garbage')).toBeNaN();
+  });
+
+  it('is not divisible by NaN', () => {
+    const fraction = new Fraction(13, 11);
+    expect(fraction.divisible(NaN)).toBe(false);
+  });
+
+  it('is not divisible by garbage', () => {
+    const fraction = new Fraction(13, 11);
+    expect(fraction.divisible('conquer')).toBe(false);
+  });
 });
diff --git a/src/fraction.ts b/src/fraction.ts
@@ -629,8 +629,12 @@ export class Fraction {
    * Ex: new Fraction("19.6").equals("98/5");
    **/
   compare(other: FractionValue) {
-    const {s, n, d} = new Fraction(other);
-    return this.s * this.n * d - s * n * this.d;
+    try {
+      const {s, n, d} = new Fraction(other);
+      return this.s * this.n * d - s * n * this.d;
+    } catch {
+      return NaN;
+    }
   }
 
   /**
@@ -639,8 +643,12 @@ export class Fraction {
    * Ex: new Fraction("19.6").equals("98/5");
    **/
   equals(other: FractionValue) {
-    const {s, n, d} = new Fraction(other);
-    return this.s === s && this.n === n && this.d === d;
+    try {
+      const {s, n, d} = new Fraction(other);
+      return this.s === s && this.n === n && this.d === d;
+    } catch {
+      return false;
+    }
   }
 
   /**
@@ -649,8 +657,12 @@ export class Fraction {
    * Ex: new Fraction("19.6").divisible("1.5");
    */
   divisible(other: FractionValue) {
-    other = new Fraction(other);
-    return !(!(other.n * this.d) || (this.n * other.d) % (other.n * this.d));
+    try {
+      other = new Fraction(other);
+      return !(!(other.n * this.d) || (this.n * other.d) % (other.n * this.d));
+    } catch {
+      return false;
+    }
   }
 
   /**