feat(tokey): adding util to convert value to a string key

src/toKey.test.ts

@@ -0,0 +1,12 @@
+import { toKey } from './toKey';
+
+describe('toKey', () => {
+  describe('when converting value to a string key', () => {
+    it('should get true', () => {
+      const symbol = Symbol(1);
+      expect(toKey(1)).toEqual('1');
+      expect(toKey(symbol)).toEqual(symbol);
+      expect(toKey(-0)).toEqual('-0');
+    });
+  });
+});

src/toKey.ts

@@ -0,0 +1,19 @@
+import { isSymbol } from './isSymbol';
+
+/** Used as references for various `Number` constants. */
+const INFINITY = 1 / 0;
+
+/**
+ * Converts `value` to a string key if it's not a string or symbol.
+ *
+ * @private
+ * @param {*} value The value to inspect.
+ * @returns {string|symbol} Returns the key.
+ */
+export function toKey(value: any): string | symbol {
+  if (typeof value === 'string' || isSymbol(value)) {
+    return value;
+  }
+  const result = `${value}`;
+  return result === '0' && 1 / value === -INFINITY ? '-0' : result;
+}