[英]Resolve deferred object after other multiple deferred objects are resolved
我对$.Deferred
经验非常有限,到目前为止,附带的代码看起来非常混乱。
本应返回承诺的函数是使用ajax请求后收到的HTML更新DOM。
它的用法如下:
this._refreshWorkspace(response.html).then(function(){
// do things after DOM update finished
});
这是功能代码:
_refreshWorkspace: function(htmlBlocks){
var dfd = $.Deferred();
if('editor' in htmlBlocks){
app.destroy(this.editor).then((function(){
this.editor.empty().append(htmlBlocks.editor);
}).bind(this)).then((function(){
app.refresh(this.editor);
}).bind(this));
}
if('listPanels' in htmlBlocks){
app.destroy(this.list).then((function(){
this.list.empty().append(htmlBlocks.listPanels);
}).bind(this)).then((function(){
app.refresh(this.list);
// other unrelated code here
dfd.resolve();
}).bind(this));
}
if('listNav' in htmlBlocks){
// similar code block
}
return dfd;
},
它似乎有效,但是只有在提供了“ listPanels” htmlBlock的情况下。 我希望在所有刷新调用之后对dfd
进行一次解析,或者,如果可能的话,甚至在所有刷新调用都解决后甚至更好。 关于如何实现此目标的任何想法?
将循环中的所有promise放入数组中,然后使用$.when
。 可悲的是,在数组中使用$.when
很丑陋:
return $.when.apply($, theArray);
...因为$.when
被设计为接受离散参数而不是数组。
像这样:
_refreshWorkspace: function(htmlBlocks){
var promises = [];
if('editor' in htmlBlocks){
promises.push(
app.destroy(this.editor).then((function(){
this.editor.empty().append(htmlBlocks.editor);
}).bind(this)).then((function(){
app.refresh(this.editor);
}).bind(this))
);
}
if('listPanels' in htmlBlocks){
promises.push(
app.destroy(this.list).then((function(){
this.list.empty().append(htmlBlocks.listPanels);
}).bind(this)).then((function(){
app.refresh(this.list);
}).bind(this))
);
}
if('listNav' in htmlBlocks){
// similar code block
}
return $.when.apply($, promises);
},
这是一个使用随机Deferred
的实时示例:
function doSomething() { var promises = []; var d1, d2, d3; d1 = new $.Deferred(); promises.push(d1.promise()); setTimeout(function() { snippet.log("Resolving d1"); d1.resolve(1); }, Math.floor(Math.random() * 1000)); d2 = new $.Deferred(); promises.push(d2.promise()); setTimeout(function() { snippet.log("Resolving d2"); d2.resolve(2); }, Math.floor(Math.random() * 1000)); d3 = new $.Deferred(); promises.push(d3.promise()); setTimeout(function() { snippet.log("Resolving d3"); d3.resolve(3); }, Math.floor(Math.random() * 1000)); return $.when.apply($, promises); } // Use it doSomething().then(function() { snippet.log("All resolved"); });
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 --> <script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
如前所述,该问题的简单答案是将单个诺言与$.when.apply(null, promiseArray)
。
但是,如果问题中的所有代码都代表要应用于所有html块的处理方式,那么您可以走得更远。
jQuery.map()
将在对象的ownProperties上运行,因此可以利用它在htmlBlocks
上进行迭代,从而产生简洁,通用的主例程,并带有两个支持的哈希。
_refreshWorkspace: function(htmlBlocks) {
var that = this; // avoids the need for .bind(this) in the promise chain and the methodsHash
var propHash = {
'editor': 'editor',
'listPanels': 'list'
};
// All the "other unrelated code" is defined here
var methodsHash = {
'editor': null,
'listPanels': function(key, obj) {
...
},
...
};
//And the main routine is a concise $.map(htmlBlocks, ...) structure.
var promises = $.map(htmlBlocks, function(html, key) {
var obj = that[propHash[key]];
return app.destroy(obj).then(function() {
obj.empty().append(html); //if empty() and append() are jQuery methods then this line is synchronous.
return app.refresh(obj);// if app.destroy() is asynch and theanable, then it seems safe to assume that app.refresh() is also asynch and theanable. Therefore return the result here.
}).then(function() {
if(methodsHash[key]) {
methodsHash[key](key, obj);
}
});
});
//Now aggregate `promises` into a single promise which resolves when all the promises resolve, or rejects when any of the promises rejects.
return $.when.apply(null, promises);
},
现在,为了满足所有其它的HTML代码,只需添加一行到propHash
和一个空的或功能methodsHash
。 如果主要例程是全面的,则无需修改。
恕我直言,这是组织代码的更好方法。
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