javascript原型访问这个 [英] javascript prototype access this

问题描述

我有一个 javascript 'class'，它包含一个调用 jquery .ajax() 的包装方法.我想传入 onSuccess 和 onError 函数处理程序，但我不确定如何.我可以使用普通的旧全局函数来做到这一点，但我正在尝试改进我的 javascript(来自 Java 背景).任何指针将不胜感激.

I have a javascript 'class' which contains a wrapper method to call jquery .ajax(). I want to pass in the onSuccess and onError function handlers, but am not sure how. I can do this with plain old global functions, but I'm trying to improve my javascript (from Java background). Any pointers would be appreciated.

在下面的_makeAjaxCall()方法中，如何引用onSuccessHandler

In the _makeAjaxCall() method below, how do I reference the onSuccessHandler

function testApp() {
  new X();
}

function X() {
  // Init X by making Ajax call, passing the func to be called on ajax return
  this._makeAjaxCall(initUrl, this.onSuccessInit, this.onError);
  // Make another ajax call to init another component
  this._makeAjaxCall(initUrl, this.onSuccessSomeOtherAjaxCall, this.onError);
}

X.prototype.onSuccessInit = function(){
  this.doStuff(...);
}

X.prototype.onSuccessSomeOtherAjaxCall = function(){
  this.doOtherStuff(...);
}


/**
 * make an ajax call, and call the provided success/error handler
 */
X.prototype._makeAjaxCall = function(url, onSuccessHandler, onError){
  $.ajax({
    url : url,    
    success : function (jsonData, textStatus, XMLHttpRequest) {
      // If I don't user 'this', the func called but I've lost my reference
      // to my instance of X
      onSuccessHandler();

      // If  I use 'this', it points to the ajax call object, not to my X object.
      this.onSuccessHandler();

    }
  });
}

推荐答案

感谢 CarlosZ &mVChr，我找到了解决方案，http://jsfiddle.net/bX35E/3/

Thanks to input from CarlosZ & mVChr, I've figured out the solution, http://jsfiddle.net/bX35E/3/

$(document).ready(function testApp() {
  new X();
});

function X() {
  console.dir(this);
  var initUrl = "/echo/json/";
  this._instanceVariable = "I AM defined!";
  // Init X by making Ajax call, passing the func to be called on ajax return
  this._makeAjaxCall(initUrl, this.onSuccessInit(), this.onError);
  // Make another ajax call to init another component
  this._makeAjaxCall(initUrl, this.onSuccessSomeOtherAjaxCall(), this.onError);
}

X.prototype.onSuccessInit = function(){
  //this.doStuff(...);
    var self = this;
    return function() {
       alert("onSuccessInit, _instanceVariable="+self._instanceVariable);
    }
}

X.prototype.onSuccessSomeOtherAjaxCall = function(){
    var self = this;
    return function() {
      alert("onSuccessSomeOtherAjaxCall, _instanceVariable="+self._instanceVariable);
    }    
}

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