ctx.requireAsync()

Asynchronously loads UMD/AMD or globally mounted scripts via URL, as well as CSS. It is suitable for RunJS scenarios that require UMD/AMD libraries such as ECharts, Chart.js, FullCalendar (UMD version), or jQuery plugins. If a library also provides an ESM version, prioritize using ctx.importAsync().

Use Cases

Can be used in any RunJS scenario where UMD/AMD/global scripts or CSS need to be loaded on demand, such as JSBlock, JSField, JSItem, JSColumn, Workflow, JSAction, etc. Typical uses: ECharts, Chart.js, FullCalendar (UMD), dayjs (UMD), jQuery plugins, etc.

Type Definition

requireAsync<T = any>(url: string): Promise<T>;

Parameters

Return Value

• The loaded library object (the first module value of the UMD/AMD callback). Many UMD libraries attach themselves to window (e.g., window.echarts), so the return value might be undefined. In such cases, access the global variable as per the library's documentation.
• Returns the result of loadCSS when a .css file is passed.

URL Format Description

• Shorthand path: e.g., echarts@5/dist/echarts.min.js. Under the default ESM CDN (esm.sh), it requests https://esm.sh/echarts@5/dist/echarts.min.js?raw. The ?raw parameter is used to fetch the original UMD file instead of an ESM wrapper.
• Full URL: Any CDN address can be used directly, such as https://cdn.jsdelivr.net/npm/dayjs@1/dayjs.min.js.
• CSS: A URL ending in .css will be loaded and injected into the page.

Difference from ctx.importAsync()

• ctx.requireAsync(): Loads UMD/AMD/global scripts. Suitable for ECharts, Chart.js, FullCalendar (UMD), jQuery plugins, etc. Libraries often attach to window after loading; the return value may be the library object or undefined.
• ctx.importAsync(): Loads ESM modules and returns the module namespace. If a library provides ESM, use ctx.importAsync() for better module semantics and Tree-shaking.

Examples

Basic Usage

// Shorthand path (resolved via ESM CDN as ...?raw)
const echarts = await ctx.requireAsync('echarts@5/dist/echarts.min.js');

// Full URL
const dayjs = await ctx.requireAsync('https://cdn.jsdelivr.net/npm/dayjs@1/dayjs.min.js');

// Load CSS and inject into the page
await ctx.requireAsync('https://cdn.example.com/theme.css');

ECharts Chart

const container = document.createElement('div');
container.style.height = '400px';
container.style.width = '100%';
ctx.render(container);

const echarts = await ctx.requireAsync('echarts@5/dist/echarts.min.js');
if (!echarts) throw new Error('ECharts library not loaded');

const chart = echarts.init(container);
chart.setOption({
  title: { text: ctx.t('Sales Overview') },
  series: [{ type: 'pie', data: [{ value: 1, name: ctx.t('A') }] }],
});
chart.resize();

Chart.js Bar Chart

async function renderChart() {
  const loaded = await ctx.requireAsync('[email protected]/dist/chart.umd.min.js');
  const Chart = loaded?.Chart || loaded?.default?.Chart || loaded?.default;
  if (!Chart) throw new Error('Chart.js not loaded');

  const container = document.createElement('canvas');
  ctx.render(container);

  new Chart(container, {
    type: 'bar',
    data: {
      labels: ['A', 'B', 'C'],
      datasets: [{ label: ctx.t('Quantity'), data: [12, 19, 3] }],
    },
  });
}
await renderChart();

dayjs (UMD)

const dayjs = await ctx.requireAsync('dayjs@1/dayjs.min.js');
console.log(dayjs?.default || dayjs);

Notes

• Return value format: UMD export methods vary; the return value may be the library object or undefined. If undefined, access it via window according to the library's documentation.
• Network dependency: Requires CDN access. In internal network environments, you can point to a self-hosted service via ESM_CDN_BASE_URL.
• Choosing between importAsync: If a library provides both ESM and UMD, prioritize ctx.importAsync().

Related

• ctx.importAsync() - Loads ESM modules, suitable for Vue, dayjs (ESM), etc.
• ctx.render() - Renders charts and other components into a container.
• ctx.libs - Built-in React, antd, dayjs, etc., no asynchronous loading required.