动态创建异步功能 [英] Dynamically create async function

问题描述

我想知道是否可以动态创建这样的异步函数:

I am wondering if it is possible to dynamically create an async function like this:

new Function('await Promise.resolve()');

预计，上一个代码将抛出:

Expectedly, the previous code throw:

Uncaught SyntaxError: await is only valid in async function

推荐答案

是的，您可以使用(非全局)

Yes, you can use the (non-global) AsyncFunction constructor to dynamically create async functions in a similar way to how new Function(...) works.

这是一个简单的例子:

const AsyncFunction = Object.getPrototypeOf(async function(){}).constructor;

function createAsync(){
    return new AsyncFunction('a', `return new Promise((resolve) => {
        setTimeout(() => {resolve(a)}, 1000)
    });`);
}

let asyncFn = createAsync();


asyncFn(1).then(/* chain the promise */);

// or inside some async function
async function myFunction(){
    await asyncFn(1);
}

请记住，您可以在动态创建的异步函数中使用await:)

And remember that you can use await inside the dynamically created async function :)

注意:AsyncFunction构造函数不是不是全局变量(例如Function是)，唯一引用它的方法是通过async function(){}实例的原型，例如在MDN文档中提到.

NOTE: The AsyncFunction contructor is not a global (like Function is), the only way to get a reference to it is via the prototype of an async function(){} instance, as mentioned in the MDN docs.

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