简体   繁体   English

如何依次调用多个异步javascript函数?

[英]How can I call multiple asynchronous javascript functions in sequence?

I am trying to call the following functions sequentially, but they don't necessarily return in the correct order. 我试图依次调用以下函数,但它们不一定以正确的顺序返回。

I then learned about asynchronous functions which can be called sequentially using "callbacks". 然后,我了解了可以使用“回调”顺序调用的异步函数。

How can I make these functions execute in sequence using callbacks? 如何使用回调按顺序执行这些功能?

$.getJSON('http://localhost/search_data.php?title='+title+'&run=annotations&jsoncallback=?', function(r1){
    $.each(make_all_titles3(r1), function (i,v) {
        $vpl.append(v);     
    });
});

$.getJSON('http://localhost/search_data.php?title='+title+'&run=Link&jsoncallback=?', function(r2){
    $.each(make_all_titles3(r2), function (i,v) {
        $vpl.append(v);     
    });
});

$.getJSON('http://localhost/search_data.php?title='+title+'&user='+user+'&run=bookmarks&jsoncallback=?', function(r3){
    $.each(make_all_titles3(r3), function (i,v) {
        $vpl.append(v);     
    });
});

$vpl.append('<div>Related Terms</div>');

$.getJSON('http://localhost/context-search.php?title='+title+'&jsoncallback=?', function(r4){
    $.each(make_all_titles3(r4), function (i,v) {
        $vpl.append(v);     
    });
});

The easiest solution would be simply nesting the calls. 最简单的解决方案是简单地嵌套调用。 Scroll down for a clean and readable solution. 向下滚动以获取清晰易读的解决方案。

function _process(r) {
    $.each(make_all_titles3(r), function (i, v) {
        $vpl.append(v);
    });
}

$.getJSON('http://localhost/search_data.php?title=' + title + '&run=annotations&jsoncallback=?', function (r) {
    _process(r);
    $.getJSON('http://localhost/search_data.php?title=' + title + '&run=Link&jsoncallback=?', function (r) {
        _process(r);
        $.getJSON('http://localhost/search_data.php?title=' + title + '&user=' + user + '&run=bookmarks&jsoncallback=?', function (r) {
            _process(r);
            $vpl.append('<div>Related Terms</div>');
            $.getJSON('http://localhost/context-search.php?title=' + title + '&jsoncallback=?', function (r) {
                _process(r);
            });
        });
    });
});

Now the clean and readable one, using the async library: 现在使用async库,干净易读:

var load = [
    { url: 'http://localhost/search_data.php?title=' + title + '&run=annotations&jsoncallback=?', before: null },
    { url: 'http://localhost/search_data.php?title=' + title + '&run=Link&jsoncallback=?', before: null },
    { url: 'http://localhost/search_data.php?title=' + title + '&user=' + user + '&run=bookmarks&jsoncallback=?', before: null },
    { url: 'http://localhost/context-search.php?title=' + title + '&jsoncallback=?', before: function() { $vpl.append('<div>Related Terms</div>'); } }
];

async.forEachSeries(load, function(item, next) {
    if(item.before) {
        item.before();
    }
    $.getJSON(item.url, function(r) {
        $.each(make_all_titles3(r), function (i, v) {
            $vpl.append(v);
        });
        next();
    });
});

See my question here: About Node's code style 在这里看到我的问题: 关于Node的代码样式
And I provide a helper function for making embedded callbacks called in line. 而且,我提供了一个辅助函数,用于使嵌入式回调直接调用。
It works both for NodeJS and browser JS. 它适用于NodeJS和浏览器JS。

ajaxcall1(parameter, function() {
    ajaxcall2(parameter, function() {
        ajaxcall3(parameter, function() {
            alert("lol");
        };
    };
});

Explanation: call the 2nd ajax call when the first returns its result and the 3d when the 2nd returns. 说明:在第一个返回其结果时调用第二个ajax调用,在第二个返回时调用3d。

use ajax async false option 使用ajax异步false选项

$.ajaxSetup({ async: false });
    // put your three get methods here
$.ajaxSetup({ async: true });

NOTE: this will halts your dynamic page functionality until your total code block's execution completes 注意:这将停止动态页面功能,直到总代码块执行完毕

声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.

 
粤ICP备18138465号  © 2020-2024 STACKOOM.COM