feat: add upperCaseFirst

src/index.ts

@@ -1,4 +1,3 @@
-export { default as Disposer } from './Disposer'
 export { default as base64Decode } from './base64Decode'
 export { default as base64Encode } from './base64Encode'
 export { default as base64UrlDecode } from './base64UrlDecode'
@@ -7,6 +6,7 @@ export { default as bindEvent } from './bindEvent'
 export { default as castArray } from './castArray'
 export { default as clamp } from './clamp'
 export { default as cssTransform } from './cssTransform'
+export { default as Disposer } from './Disposer'
 export { default as fill } from './fill'
 export { default as forOwn } from './forOwn'
 export { default as getType } from './getType'
@@ -41,4 +41,5 @@ export { default as repeat } from './repeat'
 export { default as shuffle } from './shuffle'
 export { default as stopEventPropagation } from './stopEventPropagation'
 export { default as supportPassiveEventListener } from './supportPassiveEventListener'
+export { default as upperCaseFirst } from './upperCaseFirst'
 export { default as values } from './values'

src/upperCaseFirst.ts

@@ -0,0 +1,17 @@
+const cache: { [key: string]: string } = Object.create(null)
+
+/**
+ * 转换 str 的首字母为大写。
+ *
+ * @param str 要转换的字符串
+ * @returns 转换后的字符串
+ */
+export default function upperCaseFirst(str: string): string {
+  if (!str || typeof str !== 'string') {
+    return str
+  }
+  if (!(str in cache)) {
+    cache[str] = str.charAt(0).toUpperCase() + str.slice(1)
+  }
+  return cache[str]
+}

test/index.test.ts

@@ -725,3 +725,20 @@ describe('omit', () => {
     expect(vtils.omit(obj, ['x', 'y', 'z'])).toEqual({})
   })
 })
+
+describe('upperCaseFirst', () => {
+  test('非字符串原样返回', () => {
+    [null, undefined, 0, false, true, NaN, {}, [], /ff/, () => {}].forEach(value => {
+      expect(vtils.upperCaseFirst(value as any)).toBe(value)
+    })
+  })
+  test('字符串首字母大写后返回', () => {
+    expect(vtils.upperCaseFirst('ok')).toBe('Ok')
+    expect(vtils.upperCaseFirst('Ok')).toBe('Ok')
+    expect(vtils.upperCaseFirst('OK')).toBe('OK')
+    expect(vtils.upperCaseFirst('ok no')).toBe('Ok no')
+    expect(vtils.upperCaseFirst('1ok')).toBe('1ok')
+    expect(vtils.upperCaseFirst('_ok')).toBe('_ok')
+    expect(vtils.upperCaseFirst('')).toBe('')
+  })
+})