docs: add i18n doc

README.md

@@ -57,6 +57,43 @@ $ npm install vue2-datepicker --save
 </template>
 ```
 
+## Internationalization
+
+The default language of v3.x is English. If you need other locales.
+You can import locale file.
+Once you import a locale, it becomes the active locale.
+
+```js
+import DatePicker from 'vue2-datepicker';
+import 'vue2-datepicker/index.css';
+
+import 'vue2-datepicker/locale/zh-cn';
+```
+
+You can override the default locale by `lang`.
+[Full config](https://github.com/mengxiong10/vue2-datepicker/blob/master/locale.md)
+
+```html
+<script>
+  export default {
+    data() {
+      return {
+        lang: {
+          formatLocale: {
+            firstDayOfWeek: 1,
+          },
+          monthBeforeYear: false,
+        },
+      };
+    },
+  };
+</script>
+
+<template>
+  <date-picker :lang="lang"></date-picker>
+</template>
+```
+
 ### Props
 
 | Prop                | Description                                    | Type                                        | Default        |

README.zh-CN.md

@@ -57,6 +57,41 @@ $ npm install vue2-datepicker --save
 </template>
 ```
 
+## 国际化
+
+v3.x 默认语言是英文. 可以引入语言包切换到中文.
+
+```js
+import DatePicker from 'vue2-datepicker';
+import 'vue2-datepicker/index.css';
+
+import 'vue2-datepicker/locale/zh-cn';
+```
+
+还可以通过`lang`去覆盖默认语言选项.
+[完整配置](https://github.com/mengxiong10/vue2-datepicker/blob/master/locale.md)
+
+```html
+<script>
+  export default {
+    data() {
+      return {
+        lang: {
+          formatLocale: {
+            firstDayOfWeek: 1,
+          },
+          monthBeforeYear: false,
+        },
+      };
+    },
+  };
+</script>
+
+<template>
+  <date-picker :lang="lang"></date-picker>
+</template>
+```
+
 ### Props
 
 | 属性                | 描述                                             | 类型                                        | 默认值         |

locale.md

@@ -0,0 +1,42 @@
+```js
+{
+  // the locale of formatting and parsing function
+  formatLocale: {
+    // MMMM
+    months: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
+    // MMM
+    monthsShort: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
+    // dddd
+    weekdays: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
+    // ddd
+    weekdaysShort: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
+    // dd
+    weekdaysMin: ['Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa'],
+    // first day of week
+    firstDayOfWeek: 0,
+    // first week contains January 1st.
+    firstWeekContainsDate: 1,
+    // format 'a', 'A'
+    meridiem: (h: number, _: number, isLowercase: boolean) {
+      const word = h < 12 ? 'AM' : 'PM';
+      return isLowercase ? word.toLocaleLowerCase() : word;
+    },
+    // parse ampm
+    meridiemParse: /[ap]\.?m?\.?/i;
+    // parse ampm
+    isPM: (input: string) {
+      return `${input}`.toLowerCase().charAt(0) === 'p';
+    }
+  },
+  // the calendar header, default formatLocale.weekdaysMin
+  days: [],
+  // the calendar months, default formatLocale.monthsShort
+  months: [],
+  // the calendar title of year
+  yearFormat: 'YYYY 年',
+  // the calendar title of month
+  monthFormat: 'MMM',
+  // the calendar title of month before year
+  monthBeforeYear: false,
+}
+```