feat(eq): Add eq (#642)

Co-authored-by: Sojin Park <[email protected]>

benchmarks/performance/eq.bench.ts

@@ -0,0 +1,32 @@
+import { bench, describe } from 'vitest';
+import { eq as eqToolkitCompat_ } from 'es-toolkit/compat';
+import { eq as eqLodash_ } from 'lodash';
+
+const eqToolkitCompat = eqToolkitCompat_;
+const eqLodash = eqLodash_;
+
+describe('eq', () => {
+  bench(
+    'es-toolkit/compat/eq',
+    () => {
+      eqToolkitCompat(NaN, NaN);
+      eqToolkitCompat(NaN, 0);
+      eqToolkitCompat(0, NaN);
+      eqToolkitCompat(0, -0);
+      eqToolkitCompat('abc', 'abc');
+    },
+    { time: 100 } // We need to decrease the time. because vitest throws an error if the time is too long and tested function is too fast.
+  );
+
+  bench(
+    'lodash/eq',
+    () => {
+      eqLodash(NaN, NaN);
+      eqLodash(NaN, 0);
+      eqLodash(0, NaN);
+      eqLodash(0, -0);
+      eqLodash('abc', 'abc');
+    },
+    { time: 100 }
+  );
+});

src/compat/index.ts

@@ -143,3 +143,4 @@ export { toString } from './util/toString.ts';
 export { toNumber } from './util/toNumber.ts';
 export { toInteger } from './util/toInteger.ts';
 export { toFinite } from './util/toFinite.ts';
+export { eq } from './util/eq.ts';

src/compat/util/eq.spec.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from 'vitest';
+import { eq } from './eq';
+
+describe('eq', () => {
+  it('should perform a `SameValueZero` comparison of two values', () => {
+    expect(eq()).toBe(true);
+    expect(eq(undefined)).toBe(true);
+    expect(eq(0, -0)).toBe(true);
+    expect(eq(NaN, NaN)).toBe(true);
+    expect(eq(1, 1)).toBe(true);
+
+    expect(eq(null, undefined)).toBe(false);
+    expect(eq(1, Object(1))).toBe(false);
+    expect(eq(1, '1')).toBe(false);
+    expect(eq(1, '1')).toBe(false);
+
+    const object = { a: 1 };
+    expect(eq(object, object)).toBe(true);
+    expect(eq(object, { a: 1 })).toBe(false);
+  });
+});

src/compat/util/eq.ts

@@ -0,0 +1,16 @@
+/**
+ * Performs a `SameValueZero` comparison between two values to determine if they are equivalent.
+ *
+ * @param {unknown} value - The value to compare.
+ * @param {unknown} other - The other value to compare.
+ * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
+ *
+ * @example
+ * eq(1, 1); // true
+ * eq(0, -0); // true
+ * eq(NaN, NaN); // true
+ * eq('a', Object('a')); // false
+ */
+export function eq(value?: unknown, other?: unknown): boolean {
+  return value === other || (Number.isNaN(value) && Number.isNaN(other));
+}