javascript - 在 window.onload 中使用回调

Question

我认为有一个简单的解决方案，但由于某种原因我没有得到预期的结果。我的函数如下所示:

var functionA = function(callback) {
    loadData(fromURL1); // takes some time
    loadData(fromURL2); // takes some time
    callback();         // Should be called AFTER the loadData() functions are finished
}

var myCallBackFunction = function() {
  // this function is called AFTER functionA() is finished
  alert("All my loaded data from URL1 and URL2");
}

window.onload = function() {
   functionA(myCallBackFunction);
}

不幸的是，上面的 callback() 函数不会等待 loadData() 完成，然后仅使用空数据调用警报。

我阅读了很多在线示例，但我认为我仍然缺少一些明显的东西。

Answer 1

如果loadData()是异步操作，您可以做两件事:

使用$.ajaxComplete():

var functionA = function(callback) {
    loadData(fromURL1); // takes some time
    loadData(fromURL2); // takes some time
    $.ajaxComplete(function () {
        callback();         // Should be called AFTER the loadData() functions are finished
    });
}

或者链接函数:

var functionA = function(callback) {
    loadData(fromURL1, function () {
       loadData(fromURL2, function () {
           callback();         // Should be called AFTER the loadData() functions are finished
       }); // takes some time
    }); // takes some time
}