# Weeks In Year (ISO)

URL: https://caijiao.org/dayjs/get-set/iso-weeks-in-year
Source: docs/dayjs/get-set/iso-weeks-in-year.md
Description: 获取当前年份的周数，根据 ISO weeks的定义。这依赖 IsoWeeksInYear 插件，才能正常运行

获取当前年份的周数，根据 [ISO weeks](https://en.wikipedia.org/wiki/ISO_week_date)的定义。
::: tip
这依赖 [IsoWeeksInYear](/dayjs/plugin/iso-weeks-in-year) 插件，才能正常运行
:::

```javascript
dayjs.extend(isoWeeksInYear);
dayjs.extend(isLeapYear);

dayjs("2004-01-01").isoWeeksInYear(); // 53
dayjs("2005-01-01").isoWeeksInYear(); // 52
```