javascript - setInterval 每 n 秒调用一个函数

Question

我遇到了每 1 秒调用一个函数的障碍。该代码在页面加载时运行一次，如果我手动刷新页面，它会再次运行。提前致谢!

这是代码:

//query the function S1M1StatusInt every second

setInterval(function () {S1M1StatusInt()}, 1000);

下面的 Test_tag 是一个范围为 0-4 的 int :="Skid 1"。Test_tag:是寻址 PLC 变量的语法。

// Change the Skid 1 Meter 1 block from grey to red or green based on "Skid 1".Test_tag

function S1M1StatusInt() {
    var dim1= :="Skid 1".Test_tag:;

    switch (dim1)
    {
    case 1:
        document.getElementById("S1M1Status").className ="";
        document.getElementById("S1M1Status").className = "RedBlock";
        break;
    case 2:
        document.getElementById("S1M1Status").className ="";
        document.getElementById("S1M1Status").className = "RedBlock";
        break;
    case 3: 
        document.getElementById("S1M1Status").className ="";
        document.getElementById("S1M1Status").className = "GreenBlock";
        break;
    }}

-----编辑 epascarello-----

function CheckS1M1StatusInt(){
    $.ajax({
        Type: "Get",
        url: "Meter_Status/S1M1_Status.htm",
        data: {*** what goes in here if I am retreving data***},
        success: successCheck,
        error: errorcheck
    });
}

function successCheck(data){
    switch (data)
                {
                case 1:
                    document.getElementById("S1M1Status").className ="";
                    document.getElementById("S1M1Status").className = "RedBlock";
                    break;
                case 2:
                    document.getElementById("S1M1Status").className ="";
                    document.getElementById("S1M1Status").className = "RedBlock";
                    break;
                case 3: 
                    document.getElementById("S1M1Status").className ="";
                    document.getElementById("S1M1Status").className = "GreenBlock";
                    break;
                };
    Console.log(data);
    window.setTimeout(checkServer,1000);
}

function errorCheck(){
    console.log(arguments);
}

Answer 1

问题是浏览器不会不断更新服务器端代码。 PLC 标签[无论是什么]被渲染一次，它不会不断从服务器获取新值。这就是为什么它永远不会改变。

您需要做的是向服务器发出 Ajax 调用并检查状态。

function checkServer() {
  $.ajax({
    type: "POST",
    url: "URLToPageToCheck/foo.php",
    data: { "itemX" : "whatYouWantToSendUp"},
    success: successCheck,
    error: errorCheck
  });
}

function successCheck(data){
   //Logic Check Here
   console.log(data);
   //Call checkServer again with a delay
   window.setTimeout(checkServer,1000);   
}
function errorCheck(){
    console.log(arguments);
}