javascript - 我设置ajax异步: false but not working

Question

我正在尝试从其他域获取json，我的代码如下:

var token = '';
function getData(){
  console.log("get data suc");
  for (var i=0; i < urls.length; i++){
     var code = 'http://example.com/api/'+ urls[i];
     $.ajax({
       async: false,
       url: code,
       type: 'GET',
       dataType: 'jsonp',
       success: function(data) { showData(data); },
       error: function() { console.log('ajax Failed!'); },
       beforeSend: setHeader,
     });
  }
}
function showData(data){
  $("<tr></tr>").append("<td>" + data + "</td>")
    .appendTo("#results");
  console.log(data);
}
function setHeader(xhr) {
  xhr.setRequestHeader('Authorization', token);
}

这个结果应该按照我从数组 url 给出的键的顺序显示。例如:urls = [1,2,3,4]→应该得到[一，二，三，四]但我总是得到错误的顺序!(例如:[二，一，三，四]或[三，四，二，一])发生了什么？“async: false”不起作用吗？为什么？

Answer 1

您使用的 jsonp 请求不支持 async:false。

By default, all requests are sent asynchronously (i.e. this is set to true by default). If you need synchronous requests, set this option to false. Cross-domain requests and dataType: "jsonp" requests do not support synchronous operation. Note that synchronous requests may temporarily lock the browser, disabling any actions while the request is active.

所以尝试一下

function getData() {
    function request(urls, i) {
        var code = 'http://example.com/api/' + urls[i];
        $.ajax({
            async: false,
            url: code,
            type: 'GET',
            dataType: 'jsonp',
            success: function (data) {
                showData(data);
            },
            error: function () {
                console.log('ajax Failed!');
            },
            beforeSend: setHeader,
        }).always(function () {
            i++;
            if (i < urls.length) {
                request(urls, i);
            }
        });
    }
    console.log("get data suc");
    request(urls, 0);
}