链接模块依赖项。 此方法必须在求值前调用,并且每个模块只能调用一次。

        • linker <Function>
          • specifier <string> The specifier of the requested module:

            import foo from 'foo';
            //              ^^^^^ the module specifier
          • referencingModule <vm.Module> The Module object link() is called on.

          • extra <Object>

            • assert <Object> The data from the assertion:
              import foo from 'foo' assert { name: 'value' };
              //                           ^^^^^^^^^^^^^^^^^ the assertion
              Per ECMA-262, hosts are expected to ignore assertions that they do not support, as opposed to, for example, triggering an error if an unsupported assertion is present.
          • Returns: <vm.Module> | <Promise>

        • Returns: <Promise>

        Link module dependencies. This method must be called before evaluation, and can only be called once per module.

        The function is expected to return a Module object or a Promise that eventually resolves to a Module object. The returned Module must satisfy the following two invariants:

        • It must belong to the same context as the parent Module.
        • Its status must not be 'errored'.

        If the returned Module's status is 'unlinked', this method will be recursively called on the returned Module with the same provided linker function.

        link() returns a Promise that will either get resolved when all linking instances resolve to a valid Module, or rejected if the linker function either throws an exception or returns an invalid Module.

        The linker function roughly corresponds to the implementation-defined HostResolveImportedModule abstract operation in the ECMAScript specification, with a few key differences:

        The actual HostResolveImportedModule implementation used during module linking is one that returns the modules linked during linking. Since at that point all modules would have been fully linked already, the HostResolveImportedModule implementation is fully synchronous per specification.

        Corresponds to the Link() concrete method field of Cyclic Module Records in the ECMAScript specification.