javascript 在另一个函数完成后调用一个函数
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call a function after another function is completed
提问by smtp
I am trying to call another function after load() is completed. I first tried to check with alert(), however, I see the alert before load() is done. I am able to successfully load content in load() function. However, alert() is empty.
我试图在 load() 完成后调用另一个函数。我首先尝试使用 alert() 进行检查，但是，我在 load() 完成之前看到了警报。我能够在 load() 函数中成功加载内容。但是，alert() 是空的。
$(document).ready(function(){
load();
$.when(load()).done(function(){
alert((document.getElementById('item').innerHTML));
});
function load()
{
$("#item").load("/somepage.aspx", function (response, status, xhr){
if ( status == "error" ) {
var msg = "error: ";
$( "#error" ).html( msg + xhr.status + " " + xhr.statusText );
}
});
};
});
采纳答案by Barmar
You need load()to return a promise, and then you pass this promise to $.when.
您需要load()返回一个承诺，然后将此承诺传递给$.when。
.load()doesn't return a promise, it returns the jQuery collection that it was called on (for chaining purposes). You can rewrite load()using $.get()instead, which returns a jQXHR, which implements Deferred(that's jQuery's promise class).
.load()不返回承诺，它返回调用它的 jQuery 集合（用于链接目的）。你可以改写load()using $.get()，它返回一个jQXHR，它实现了Deferred（这是jQuery的promise类）。
var p = load();
$.when(p).done(function() {
alert($("#item").html());
});
function load() {
return $.get("/somepage.aspx", function (response, status, xhr){
$("#item").html(response);
if ( status == "error" ) {
var msg = "error: ";
$( "#error" ).html( msg + xhr.status + " " + xhr.statusText );
}
});
}
You don't actually need to use $.when, you can just write:
你实际上并不需要使用$.when，你可以只写：
p.done(function() { ... });
回答by Nikhil Aggarwal
You can use callback functions and update your code to following
您可以使用回调函数并将代码更新为以下
$(document).ready(function(){
load(function(){
alert((document.getElementById('item').innerHTML));
});
function load(callback)
{
$("#item").load("/somepage.aspx", function (response, status, xhr){
if ( status == "error" ) {
var msg = "error: ";
$( "#error" ).html( msg + xhr.status + " " + xhr.statusText );
}
if(callback) {
callback();
}
});
};
});
回答by Sagi
You can use the new PromisesAPI which is already implemented in most major browsers.
您可以使用已在大多数主要浏览器中实现的新PromisesAPI。
var jsonPromise = new Promise(function(resolve, reject) {
// do a thing, possibly async, then…
if ( /* everything turned out fine */ ) {
resolve("Stuff worked!");
}
else {
reject(Error("It broke"));
}
});
jsonPromise.then(function(data) {
console.log(result); // "Stuff worked!"
}, function(err) {
console.log(err); // Error: "It broke"
});
