javascript chainning从回调中返回 [英] javascript chainning return this from callback

问题描述

这里是剪切的

$

b $ b

  create：function（currentView，data）{
 var itsMe = this; 
 this.thumbsWrapper = this.templates.wrapper（）。hide（）; 
 currentView.append（this.thumbsWrapper）; 
 this.thumbsWrapper.fadeIn（fast，function（）{
 return itsMe; 
}）; 
}，
 
 var l = list（）。create（currentView）; //需要返回，我可以使用链接
  

var l现在未定义，如果我使用fadeIn与回调...
如果我不使用fadeIn与回调它返回obj

任何人的想法为什么？

解决方案

什么@Felix Kling说是正确的，你不返回任何东西。如果您要返回 itsMe ，您需要执行以下操作：

  create ：function（currentView，data）{
 var itsMe = this; 
 this.thumbsWrapper = this.templates.wrapper（）。hide（）; 
 currentView.append（this.thumbsWrapper）; 
 this.thumbsWrapper.fadeIn（fast）; 
 return itsMe; 
} 
  

如果你想链接，这应该就足够了。

如果您想在淡出完成时获取对 itsMe 的引用，您需要传递自己的callback：

  create：function（currentView，data，callback）{
 var itsMe = this; 
 this.thumbsWrapper = this.templates.wrapper（）。hide（）; 
 currentView.append（this.thumbsWrapper）; 
 this.thumbsWrapper.fadeIn（fast，function（）{
 callback（itsMe）; 
}）; 
} 
 
 
 list（）。create（function）{
 console.log（fade out complete）; 
 console.log （itsMe is，that）; 
}）; 
  

如果你想有一个链接模式，它会执行链中的下一个函数完成后，您将需要传递一个引用 this ，但是一个对象可以排队命令，顺序实现每个命令。

i've tried to get a return this from a callback, but i always get undefined.

here is the snipped

create: function(currentView, data){
    var itsMe = this; 
    this.thumbsWrapper = this.templates.wrapper().hide();
    currentView.append(this.thumbsWrapper);
    this.thumbsWrapper.fadeIn("fast", function(){
        return itsMe;                                                 
    });
},

var l = list().create(currentView); //need teh return that i can use chaining

the var l is now undefined, if i use the fadeIn with a callback... if i dont use fadeIn with the callback it returns the obj

anyone an idea why?

解决方案

What @Felix Kling say is correct, you are not returning anything. If you want to return itsMe you will need to do:

create: function(currentView, data){
    var itsMe = this; 
    this.thumbsWrapper = this.templates.wrapper().hide();
    currentView.append(this.thumbsWrapper);
    this.thumbsWrapper.fadeIn("fast");
    return itsMe;    
}

Which should suffice if you want chaining.

If you want to get a reference to itsMe when the fadeout is finished, you will need to pass your own callback:

create: function(currentView, data, callback){
    var itsMe = this; 
    this.thumbsWrapper = this.templates.wrapper().hide();
    currentView.append(this.thumbsWrapper);
    this.thumbsWrapper.fadeIn("fast", function(){ 
        callback(itsMe);
    });  
}


list().create(function (that) {
    console.log("fade out complete");
    console.log("itsMe is", that);
});

And if you want to have a chaining pattern, which will execute the next function in the chain when fadeout is finished, you will need to pass not a reference to this but an object which can queue up commands, implement each command sequentially.

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