Question

我正在调用一个函数，使用jQuery ajax函数以毫秒为间隔调用webservice。如果第一个请求之一较慢，则它们会重叠，成功函数将使用旧的请求响应。

这是我的ajax调用函数：

function runRequest(url, request, token, handleSuccess, handleError) {
    $.ajax({
        url: url,
        type: "POST",
        data: JSON.stringify(request),
        headers: {
            "Authorization": "Basic " + btoa(/* ... */),
            "Content-Type": "application/json"
        },
        success: function (data, status, xhr) {
            handleSuccess(data);
        },
        error: function (xhr, status, error) {
            handleError(xhr);
        }
    });
}

如何预防？我试图节省创建请求的时间，管理那个时间到成功和错误函数，检查它是否响应，但它不会工作..

同步的ajax请求不是选项..：/

Answer 1

解决此问题的快捷方法是为您的请求添加时间戳或计数器，并在handleSuccess时更新。

handleSuccess = (function () {
    // closure scope this variable so only handleSuccess sees it.
    var latest = 0;
    return function handleSuccess(timestamp, data) {
        if (timestamp < latest) { return; }
        latest = timestamp;
        // the normal body of handleSuccess goes here
    };
})();
function runRequest(url, request, token, handleSuccess, handleError) {
    var timestamp = (new Date()).valueOf();
    $.ajax({
        url: url,
        type: "POST",
        data: JSON.stringify(request),
        headers: {
            "Authorization": "Basic " + btoa(/* ... */),
            "Content-Type": "application/json"
        },
        success: function (data, status, xhr) {
            handleSuccess(timestamp, data);
        },
        error: function (xhr, status, error) {
            handleError(xhr);
        }
    });
}

您可以在此演示中看到handleSuccess包装器的工作方式：https://jsfiddle.net/n6j1psut/

Answer 2

正如我评论的那样：

var count = 0;
function runRequest(url, request, token, handleSuccess, handleError, index) {
    count = index;
    $.ajax({
        url: url,
        type: "POST",
        data: JSON.stringify(request),
        headers: {
            "Authorization": "Basic " + btoa(/* ... */),
            "Content-Type": "application/json"
        },
        success: function (data, status, xhr) {
            if(index == count){
                handleSuccess(data);
            }
        },
        error: function (xhr, status, error) {
            if(index == count){
                handleError(xhr);
            }
        }
    });
}

runRequest(..., count++);

Answer 3

你需要检查一下你是否已经在进行中并等到它完成了例如：

var isRunning = false;

function call()
{
     if(isRunning)
      return; // still working... please wait.
     isRunning = true;

    $.ajax({
            url: url,
            type: "POST",
            data: JSON.stringify(request),
            headers: {
                "Authorization": "Basic " + btoa(/* ... */),
                "Content-Type": "application/json"
            },
            success: function (data, status, xhr) {
                handleSuccess(data);
                isRunning = false;
            },
            error: function (xhr, status, error) {
                handleError(xhr);
                isRunning = false;
            }
        });
  }

jQuery ajax请求 - 防止重叠

3 个答案: