Javascript在回调函数中破坏for循环 [英] Javascript breaking a for loop inside a callback function

问题描述

我有如下代码:

function test(obj) {

    if(//some conditon) {
        obj.onload();
    }else{
        obj.onerror();
    }
}


for(var i=0;i<4;i++){   

    test({
        onload:function(e){          
            //some code to run
        },
        onerror:function(e){
            break;
        }


    });
}

要点是 test() 函数是一个发出 XHR 请求的函数(它实际上是 Appcelerator Titanium 平台的 API，所以我无法控制它)并且我正在循环调用测试函数.我需要中断 onerror 函数上的循环，但我收到一条错误消息，指出中断不在循环或 switch 语句中.我该如何重写?

The gist is the test() function is a function to make an XHR request (it is actually an API of the Appcelerator Titanium platform so I have no control over it) and I'm looping something to call the test function. I need to break the loop on the onerror function, but I get an error saying the break is not inside a loop or switch statement. How can I rewrite this?

推荐答案

如果您的代码示例确实代表了一些实际代码(即所有处理都在同一个事件循环滴答中完成)，您可以执行以下操作:

If your code sample does represent some actual code (i.e. all the processing is done in the same event loop tick), you may do the following:

function test(obj) {

    if (some_condition) {
        return obj.onload();
    } else {
        return obj.onerror();
    }
}

var result;
for(var i=0; i<4; i++){   

    result = test({
        onload:function(e){          
            //some code to run
            return true;
        },
        onerror:function(e){
            return false;
        }


    });

    if (!result) {
        break;
    }
}

否则，如果有一些异步完成，你必须顺序调用test，而不是并行调用.例如，

Otherwise, if there is something asynchronous done, you have to call test sequentially, and not in parallel. For example,

function test(obj) {
    doSomeAjaxRequest(arguments, function (err, result) {
        if (some_condition) {
            obj.onload();
        } else {
            obj.onerror();
        }
    });
}

var f = function (i) {
    if (i >= 4) return;
    test({
        onload:function(e){          
            //some code to run
            f(i+1);
        },
        onerror:function(e){
            break;
        }
    });
}

f(0);

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