resolve(specifier, context, defaultResolve)

注意：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。

• specifier <string>
• context <Object>
  • conditions <string[]>
  • importAssertions <Object>
  • parentURL <string> | <undefined>
• defaultResolve <Function> Node.js 默认解析器。
• 返回: <Object>
  • format <string> | <null> | <undefined> 'builtin' | 'commonjs' | 'json' | 'module' | 'wasm'
  • url <string> 导入目标的绝对网址（例如 file://…）

resolve 钩子返回给定模块说明符和父 URL 的解析文件 URL，以及可选的格式（例如 'module'）作为对 load 钩子的提示。 如果指定了格式，则 load 钩子最终负责提供最终的 format 值（可以随意忽略 resolve 提供的提示）；如果 resolve 提供了 format，则需要自定义 load 钩子，即使只是通过 Node.js 默认 load 钩子的值。

模块说明符是 import 语句或 import() 表达式中的字符串，父 URL 是导入此模块的 URL，如果这是应用程序的主要入口点，则为 undefined

context 中的 conditions 属性是适用于此解析请求的包导出条件的条件数组。 它们可用于在别处查找条件映射或在调用默认解析逻辑时修改列表。

当前的包导出条件始终在传入钩子的 context.conditions 数组中。 为了在调用 defaultResolve 时保证默认的 Node.js 模块说明符解析行为，传给它的 context.conditions 数组必须包含最初传到 resolve 钩子的 context.conditions 数组的所有元素。

/**
 * @param {string} specifier
 * @param {{
 *   conditions: string[],
 *   parentURL: string | undefined,
 * }} context
 * @param {Function} defaultResolve
 * @returns {Promise<{ url: string }>}
 */
export async function resolve(specifier, context, defaultResolve) {
  const { parentURL = null } = context;
  if (Math.random() > 0.5) { // 一些条件。
    // 对于部分或全部说明符，做一些自定义逻辑来解决。
    // 总是返回 {url: <string>} 形式的对象。
    return {
      url: parentURL ?
        new URL(specifier, parentURL).href :
        new URL(specifier).href,
    };
  }
  if (Math.random() < 0.5) { // 另一个条件。
    // 当调用 `defaultResolve` 时，可以修改参数。
    // 在这种情况下，它为匹配条件导出添加了另一个值。
    return defaultResolve(specifier, {
      ...context,
      conditions: [...context.conditions, 'another-condition'],
    });
  }
  // 对于所有其他说明符，请遵循 Node.js。
  return defaultResolve(specifier, context, defaultResolve);
}

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

• specifier <string>
• context <Object>
  • conditions <string[]>
  • importAssertions <Object>
  • parentURL <string> | <undefined>
• defaultResolve <Function> The Node.js default resolver.
• Returns: <Object>
  • format <string> | <null> | <undefined> 'builtin' | 'commonjs' | 'json' | 'module' | 'wasm'
  • url <string> The absolute url to the import target (such as file://…)

The resolve hook returns the resolved file URL for a given module specifier and parent URL, and optionally its format (such as 'module') as a hint to the load hook. If a format is specified, the load hook is ultimately responsible for providing the final format value (and it is free to ignore the hint provided by resolve); if resolve provides a format, a custom load hook is required even if only to pass the value to the Node.js default load hook.

The module specifier is the string in an import statement or import() expression, and the parent URL is the URL of the module that imported this one, or undefined if this is the main entry point for the application.

The conditions property in context is an array of conditions for package exports conditions that apply to this resolution request. They can be used for looking up conditional mappings elsewhere or to modify the list when calling the default resolution logic.

The current package exports conditions are always in the context.conditions array passed into the hook. To guarantee default Node.js module specifier resolution behavior when calling defaultResolve, the context.conditions array passed to it must include all elements of the context.conditions array originally passed into the resolve hook.

/**
 * @param {string} specifier
 * @param {{
 *   conditions: string[],
 *   parentURL: string | undefined,
 * }} context
 * @param {Function} defaultResolve
 * @returns {Promise<{ url: string }>}
 */
export async function resolve(specifier, context, defaultResolve) {
  const { parentURL = null } = context;
  if (Math.random() > 0.5) { // Some condition.
    // For some or all specifiers, do some custom logic for resolving.
    // Always return an object of the form {url: <string>}.
    return {
      url: parentURL ?
        new URL(specifier, parentURL).href :
        new URL(specifier).href,
    };
  }
  if (Math.random() < 0.5) { // Another condition.
    // When calling `defaultResolve`, the arguments can be modified. In this
    // case it's adding another value for matching conditional exports.
    return defaultResolve(specifier, {
      ...context,
      conditions: [...context.conditions, 'another-condition'],
    });
  }
  // Defer to Node.js for all other specifiers.
  return defaultResolve(specifier, context, defaultResolve);
}