Generator.prototype.throw()

¥Syntax

generatorInstance.throw(exception)

¥Parameters

exception

要抛出的异常。出于调试目的，将其设置为 instanceof Error 很有用。

¥Return value

如果抛出的异常被 try...catch 捕获并且生成器恢复生成更多值，它将返回具有两个属性的 Object：

¥If the thrown exception is caught by a try...catch and the generator resumes to yield more values, it will return an Object with two properties:

done

布尔值：

• 如果生成器函数的控制流已到达末尾，则为 true。
• false 如果生成器函数能够产生更多值。

value

从下一个 yield 表达式产生的值。

¥Exceptions

如果抛出的异常没有被 try...catch 捕获，则传递给 throw() 的 exception 将从生成器函数中抛出。

¥If the thrown exception is not caught by a try...catch, the exception passed to throw() will be thrown out from the generator function.

¥Description

调用 throw() 方法时，可以将其视为在生成器主体的当前挂起位置处插入了 throw exception; 语句，其中 exception 是传递给 throw() 方法的异常。因此，在典型的流程中，调用 throw(exception) 将导致生成器抛出异常。但是，如果 yield 表达式包含在 try...catch 块中，则可能会捕获错误，并且控制流可以在错误处理后恢复，或者正常退出。

¥The throw() method, when called, can be seen as if a throw exception; statement is inserted in the generator's body at the current suspended position, where exception is the exception passed to the throw() method. Therefore, in a typical flow, calling throw(exception) will cause the generator to throw. However, if the yield expression is wrapped in a try...catch block, the error may be caught and control flow can either resume after error handling, or exit gracefully.

¥Examples

¥Using throw()

以下示例显示了一个简单的生成器以及使用 throw 方法引发的错误。像往常一样，错误可以被 try...catch 块捕获。

¥The following example shows a simple generator and an error that is thrown using the throw method. An error can be caught by a try...catch block as usual.

function* gen() {
  while (true) {
    try {
      yield 42;
    } catch (e) {
      console.log("Error caught!");
    }
  }
}

const g = gen();
g.next();
// { value: 42, done: false }
g.throw(new Error("Something went wrong"));
// "Error caught!"
// { value: 42, done: false }

¥See also

• function*