Javascript无法控制方法

Question

我在下面的代码中遇到的问题很少。任何人都可以帮忙吗？

1. getStatusUsingAjax methid中的if（currentStatus！=“undefined”）块无效。
2. 无法控制getStatusUsingAjax方法

 $(document).ready(
   loadStatus()

 );

 function loadStatus(x) {

     $('.a-IRR-table tr').each(function(i) {
           var val = $(this).find("td").eq(0).text();
           link = $(this).find("td").eq(0).find("a").attr("href");
           linkTag = $(this).find("td").eq(0).find("a");

           `if ((val !== "-") && (val !== "")) {
          console.log("val is" + val);
          if (verifyrequestArray(val)) {
           console.log("inside second if");

          } else {
            console.log("inside else");
            sleep(1.5 * 1000);
            var updatedStatus2 = getStatusUsingAjax(val, link);
            console.log("UpdatedStatus2 is " + updatedStatus2);
            setTooltip(linkTag, updatedStatus2);
          }



        }
      });

    }

        function verifyrequestArray(id) {

      var newArray = requestArray.toString().split('-');
      console.log("NewArray is :" + newArray);
      for (i = 0; i < newArray.length; i++) {
        // I'm looking for the index i, when the condition is true
        if (newArray[i] === id) {
          console.log("request id found" + newArray[i]);
          break;
        } else {
          console.log("request id not found" + newArray[i]);
          return false;
        }
      }
    }



        function getStatusUsingAjax(requestValue, currentlink) {

      console.log("patch req: " + requestValue);
      console.log("Link is " + currentlink);
      var currentStatus;
      GM_xmlhttpRequest({
        method: "GET",
        url: currentlink,
        onload: function(response) {

          if ($(response.responseText).find("#P16_STATUS2").size() === 1) {
            currentStatus = $(response.responseText).find("#P16_STATUS2").text();
            console.log("Current Status from #P16_STATUS2 is :" + currentStatus);
            console.log("Final URL is " + response.finalUrl);
          }


        }

      });
      // console.log("Final URL is " +response.finalUrl);

      if (currentStatus != "undefined") {

        var pusharr = [requestValue + "-" + currentStatus];
        requestArray.push(pusharr);
        console.log("Updated Array is " + requestArray);
        return currentStatus;
      }
    }

       function setTooltip(currentTag, status2) {
        console.log("in settooltip" + currentTag);
        currentTag.attr("title", status2); //setting status a tooltip
    }

错误出现的任何线索？

Answer 1

fn getStatusUsingAjax是异步的，您无法使用以下方式获取返回值：

var updatedStatus2 = getStatusUsingAjax(val, link);

你sholud创建回调：

function getStatusUsingAjax(val, link, callback){
//...
// do not use return currentStatus, call calback fn instead
callback(currentStatus)
}

并使用：

调用它

getStatusUsingAjax(val, link, function(updatedStatus2){ 
  console.log("UpdatedStatus2 is " + updatedStatus2);
  setTooltip(linkTag, updatedStatus2); 
});