fix: optimize isJsonString function

Author: chandq

src/tooltip.ts

@@ -7,7 +7,7 @@
  * 		onmouseenter="handleMouseEnter({'#root', title: 'title content', event: event})">title content </span>
  */
 
-import { getStrWidthPx } from './string';
+import { getStrWidthPx } from './dom';
 
 interface ITooltipParams {
   rootElId: string;

src/type.ts

@@ -54,14 +54,14 @@ export const isDate = (any: unknown): any is Date => typeIs(any) === 'Date';
 export const isError = (any: unknown): any is Error => typeIs(any) === 'Error';
 export const isRegExp = (any: unknown): any is RegExp => typeIs(any) === 'RegExp';
 /**
- * 判断一个字符串是否为有效的 JSON
+ * 判断一个字符串是否为有效的 JSON, 若有效则返回有效的JSON对象，否则false
  * @param {string} str
- * @return {boolean}
+ * @return {Object | boolean}
  */
-export function isJsonString(str: string): boolean {
+export function isJsonString(str: string): Object | boolean {
   try {
     const parsed = JSON.parse(str);
-    return typeof parsed === 'object' && parsed !== null;
+    return typeof parsed === 'object' && parsed !== null ? parsed : false;
   } catch (e) {
     return false;
   }

test/type.test.ts

@@ -95,6 +95,9 @@ test('isRegExp', () => {
 test('isJsonString', () => {
   const jsonString = '{"name": "John", "age": 30}';
   const invalidJsonString = '{"name": "John", "age": 30';
-  expect(isJsonString(jsonString)).toBe(true);
+  expect(isJsonString(jsonString)).toEqual({
+    name: 'John',
+    age: 30
+  });
   expect(isJsonString(invalidJsonString)).toBe(false);
 });