globalPreload()

加载器 API 正在重新设计。 这个钩子可能会消失，或者它的签名可能会改变。 不要依赖下面描述的 API。

在此 API 的先前版本中，此钩子被命名为 getGlobalPreloadCode。

• 返回: <string>

有时可能需要在应用程序运行所在的同一全局范围内运行一些代码。 此钩子允许返回在启动时作为宽松模式脚本运行的字符串。

类似于 CommonJS 封装器的工作方式，代码在隐式函数范围内运行。 唯一的参数是类似 require 的函数，可用于加载内置函数，如 "fs"：getBuiltin(request: string)。

如果代码需要更高级的 require 特性，则必须使用 module.createRequire() 构建自己的 require。

/**
 * @param {{
     port: MessagePort,
   }} utilities Things that preload code might find useful
 * @returns {string} 在应用程序启动之前运行的代码
 */
export function globalPreload(utilities) {
  return `\
globalThis.someInjectedProperty = 42;
console.log('I just set some globals!');

const { createRequire } = getBuiltin('module');
const { cwd } = getBuiltin('process');

const require = createRequire(cwd() + '/<preload>');
// [...]
`;
}

为了允许应用程序和加载程序之间进行通信，预加载代码中提供了另一个参数：port。 这可以作为加载器钩子的参数和钩子返回的源文本内部。 必须注意正确调用 port.ref() 和 port.unref() 以防止进程处于无法正常关闭的状态。

/**
 * This example has the application context send a message to the loader
 * and sends the message back to the application context
 * @param {{
     port: MessagePort,
   }} utilities Things that preload code might find useful
 * @returns {string} 在应用程序启动之前运行的代码
 */
export function globalPreload({ port }) {
  port.onmessage = (evt) => {
    port.postMessage(evt.data);
  };
  return `\
    port.postMessage('console.log("I went to the Loader and back");');
    port.onmessage = (evt) => {
      eval(evt.data);
    };
  `;
}

The loaders API is being redesigned. This hook may disappear or its signature may change. Do not rely on the API described below.

In a previous version of this API, this hook was named getGlobalPreloadCode.

• Returns: <string>

Sometimes it might be necessary to run some code inside of the same global scope that the application runs in. This hook allows the return of a string that is run as a sloppy-mode script on startup.

Similar to how CommonJS wrappers work, the code runs in an implicit function scope. The only argument is a require-like function that can be used to load builtins like "fs": getBuiltin(request: string).

If the code needs more advanced require features, it has to construct its own require using module.createRequire().

/**
 * @param {{
     port: MessagePort,
   }} utilities Things that preload code might find useful
 * @returns {string} Code to run before application startup
 */
export function globalPreload(utilities) {
  return `\
globalThis.someInjectedProperty = 42;
console.log('I just set some globals!');

const { createRequire } = getBuiltin('module');
const { cwd } = getBuiltin('process');

const require = createRequire(cwd() + '/<preload>');
// [...]
`;
}

In order to allow communication between the application and the loader, another argument is provided to the preload code: port. This is available as a parameter to the loader hook and inside of the source text returned by the hook. Some care must be taken in order to properly call port.ref() and port.unref() to prevent a process from being in a state where it won't close normally.

/**
 * This example has the application context send a message to the loader
 * and sends the message back to the application context
 * @param {{
     port: MessagePort,
   }} utilities Things that preload code might find useful
 * @returns {string} Code to run before application startup
 */
export function globalPreload({ port }) {
  port.onmessage = (evt) => {
    port.postMessage(evt.data);
  };
  return `\
    port.postMessage('console.log("I went to the Loader and back");');
    port.onmessage = (evt) => {
      eval(evt.data);
    };
  `;
}