Question

我创建了一个简单的XHR长轮询类，它接受初始化的http请求，然后解析流并在数据片段到达时自动调用函数。

要真正理解我的所作所为，请参阅课程：

function longPollingRequest(http) {
  //Define how fragments of data are separated
  // onData() is called for every received fragment
  this.delimiter = "\n";
  //Dummy callback
  this.onData = function() {};
  //Whether or not to automatically reconnect to the stream source (does not work yet)
  this.reconnect = false;
  //Self reference for event functions
  var _this = this;
  //Offset in http.responseText (this one cannot be truncnated until the request is over)
  var seeker = 0;
  //Whether or not connected
  var connected = false;
  //Assign events to http request
  http.onreadystatechange = readState;
  http.onprogress = parseData;


  // OVerride HTTPRequest send method for this instance
  var oldSend = http.send;
  http.send = function() {
    connected = true;
    oldSend.apply(this, arguments);
  }

  //Define readystate event
  function readState() {
    if(this.readyState==2) {
    }
    if(this.readyState==3||this.readyState==4) {
      parseData();
    }  
    if(this.readyState==4) {
      if(_this.reconnect==true)  //Eventually reconnect
        _this.reconnect(); 
    }
  }  
  function parseData(r) {     
    //Start at the current position in the input, anything before has already been sent to onData()
    var seektmp = seeker;
    //Loop through the input and seek delimiters
    while(seektmp<this.responseText.length) {
      if(this.responseText[seektmp]==_this.delimiter) {
        //If a delimiter has been found, send the fragment before to onData
        _this.onData(this.responseText.substr(seeker+1,seektmp-1-seeker));
        //Skip the original seeker to the end of data that has been read (+1 for delimiter)
        seeker=seektmp+1;   //todo: +delimiter size, instead of just 1
      }      
      //iterate 1 character, until the end of data 
      seektmp++;
    }  
  }
}

用法：

var http = /**cross browser create request**/;
http.open(...);
var poll = new longPollingRequest(http);
http.send();

现在重点是，我可能不会像这样重新连接http请求：

var http = /**cross browser create request**/;
http.open(...);
http.onload = function() {
   this.send();   //ERROR: resource not initialised (requires open() call)
}
http.send();

那么，有没有办法在不知道请求目标的情况下重新连接？

重新连接XHR请求而不再调用open method（）

0 个答案: