javascript – 为什么在_jax请求中将“_ = 1389258551926”作为查询字符串参数发送？

参见英文答案 > Who Add “_” Single Underscore Query Parameter?                                    4个
>            Preventing jQuery from cache busting resources loaded during AJAX callbacks that use the `html(…)` function                                    1个
我正在使用JQuery Ajax向我的动作类发送请求,其中包含数据：{campaignId：campaignId}但是_ = 1389258551926也作为数据发送.

我的ajax请求功能是：

$('#submit').click(function() {
    var campaignId = $('#campaign').val();
    alert("Ajax request ; Camp : " + campaignId);
    $.ajax({
        type: "get",
        url: "getCampData",
        data: {campaignId: campaignId},
        dataType: "json"
    }).done(function(data) {
        alert("Camp List : " + data.campList);
});

查询字符串参数：

campaignId=Test&_=1389258551927

为什么这个额外参数作为数据发送？

解决方法:

此参数是时间戳.你可以看到它与控制台中的内容完全相同

Date.Now()

这样做是为了确保URL更改并避免接收页面的缓存版本.

它在the documentation中描述：

cache (default: true, false for dataType ‘script’ and ‘jsonp’)

Type: Boolean If set to false, it will force requested pages not to be
cached by the browser. Note: Setting cache to false will only work
correctly with HEAD and GET requests. It works by appending
“_={timestamp}” to the GET parameters. The parameter is not needed for
other types of requests, except in IE8 when a POST is made to a URL
that has already been requested by a GET.