javascript - 智能轮询功能

Question

您好，我想制作一个智能轮询功能，其中每 4 个空响应后，间隔应加倍。但如果间隔达到最大间隔，则应仅保留该值。应该为它编写什么函数。

这是从 php 代码获取响应的代码。

function updateChat() {
    console.log("inside updatechat");

    setInterval(function()

        $.ajax({
            //type: "POST",
            url: "file.php",
            //data: id,
            //dataType: JSON,

            success: function(response) {
                var result = JSON.parse(response);
                //console.log("Result is " +result);

                for (var i in result) {

                    $(".message_box").append('<p class = "shout_msg">' + result[i] + '</p>');
                    $(".message_box").scrollTop($(".message_box")[0].scrollHeight);
                }

            }


        }), interval);

}

我的投票功能是什么？

Answer 1

setInterval 每个固定时间间隔调用回调...您需要的是 setTimeout:

var INITIAL_INTERVAL = 500; // 0.5 sec
var MAX_INTERVAL = 120000; // two minutes
var interval = INITIAL_INTERVAL;

var pollingFunction = function() {
    $.ajax({
        //type: "POST",
        url: "file.php",
        //data: id,
        //dataType: JSON,

        success: function(response) {
            var result = JSON.parse(response);
            if (result.length == 0) { // or whatever condition to check return of empty result
                 // empty result - poll server at slower pace
                 interval *= 2;
                 if (interval > MAX_INTERVAL) {
                     interval = MAX_INTERVAL;
                 }
            }
            else { 
                 // reset interval to initial quick value
                 interval = INITIAL_INTERVAL;
            }
            //console.log("Result is " +result);

            for (var i in result) {

                $(".message_box").append('<p class = "shout_msg">' + result[i] + '</p>');
                $(".message_box").scrollTop($(".message_box")[0].scrollHeight);
            }

            // activate the pollingFunction again after 'interval' ms
            // important - set the timeout again of the polling function
            setTimeout(pollingFunction, interval);
        }


    })
 }

 // activate the polling function the first time after interval ms
 // important - set the timeout once (or call the polling function once) from outer scope.
 setTimeout(pollingFunction, interval);