如何从异步函数返回 [英] How to return from an async function

问题描述

我的代码如下:

myObject.myMethod('imageCheck', function () {
    var image = new Image();
    image.onerror = function() {
        return false;

    };  
    image.onload = function() {
        return true;
    };
    image.src = 'http://www.example.com/image.jpg';         
});

但是，它不起作用，可能是因为我的返回仅从匿名函数返回，而不是从名为imageCheck的函数返回.我该如何重写它，以使整个函数返回为true或false?

But, it doesn't work, assumedly because my returns only return from the anonymous function, not from the one called imageCheck. How can I rewrite this so that the whole function is returned as true or false?

推荐答案

您必须使用回调，例如:

you have to use callbacks, for example:

myObject.myMethod('imageCheck', function () {
    var image = new Image();
    image.onerror = function() {
        returnCallback(false);

    };  
    image.onload = function() {
        returnCallback(true);
    };
    image.src = 'http://www.example.com/image.jpg';         
});

function returnCallback(bool){
    //do something with bool
}

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