JSON Eval函数中的意外标识符

Unexpected identifier in JSON Eval function

本文关键字：意外 标识符 Eval 函数 JSON      更新时间：2023-09-26

这是我在某个地方复制的用于评级页面的代码。这段代码在我的本地主机上工作得很好，但当我把它上传到服务器上时，它返回语法错误。

 function rtgAjax(elm, ratev) {
   var cerere_http =  get_XmlHttp();        // get XMLHttpRequest object
 // define data to be send via POST to PHP (Array with name=value pairs)
  var datasend = Array();
  for(var i=0; i<elm.length; i++) datasend[i] = 'elm[]='+elm[i];
     // joins the array items into a string, separated by '&'
     datasend = datasend.join('&')+'&rate='+ratev;
     cerere_http.open("POST", 'ratingfiles/ratings.php', true);         
       //     crate the request
  cerere_http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");              // header for POST
  cerere_http.send(datasend);       
 //  make the ajax request, poassing the data
 // checks and receives the response
 cerere_http.onreadystatechange = function() {
if (cerere_http.readyState == 4) {
  // receives a JSON with one or more item:['totalrate', 'nrrates', renot]
  eval(' var jsonitems = ' + cerere_http.responseText);
  // if jsonitems is defined variable
  if (jsonitems) {
    // parse the jsonitems object
    for(var rtgitem in jsonitems) {
      var renot = jsonitems[rtgitem][2];        
  // determine if the user can rate or not
      // if renot=3 displaies alert that already voted, else, continue with the rating reactualization
       if(renot == 3) {
        alert("You already voted 'n You can rate again tomorrow");
        window.location.reload(true);       // Reload the page
      }
      else addRtgData(rtgitem, jsonitems[rtgitem][0], jsonitems[rtgitem][1], renot);    // calls function that shows rating
    }
  }
这条线

, 

 eval(' var jsonitems = ' + cerere_http.responseText);

返回语法错误:Unexpected Identifier

eval不应该这样使用。相反，试着这样做:

var jsonitems;
try {
    jsonitems = JSON.parse(cerere_http.responseText);
}
catch(e) {alert("Failed to parse JSON: "+e);}
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