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public/docs/ts/latest/tutorial/toh-pt6.jade

@@ -765,56 +765,98 @@ block observables-section
     * `distinctUntilChanged` ensures that we only send a request if the filter text changed.
     There's no point in repeating a request for the same search term.
     
+    * `distinctUntilChanged`确保只在过滤条件变化时才发送请求，这样就不会重复请求同一个搜索词了。
+    
     * `switchMap` calls our search service for each search term that makes it through the `debounce` and `distinctUntilChanged` gauntlet.
     It cancels and discards previous search observables, returning only the latest search service observable.
+    
+    * `switchMap`会为每个从`debounce`和`distinctUntilChanged`中通关的搜索词调用搜索服务。它会丢弃以前的搜索Observable，只保留最近的。
 
   .l-sub-section
     :marked
       The [switchMap operator](https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/core/operators/flatmaplatest.md)
       (formerly known as "flatMapLatest") is very clever.
 
+      [switchMap操作符](https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/core/operators/flatmaplatest.md)
+      (以前叫"flatMapLatest")是非常智能的。
+
       Every qualifying key event can trigger an http call.
       Even with a 300ms pause between requests, we could have multiple http requests in flight 
       and they may not return in the order sent.
+      
+      每次符合条件的按键事件都会触发一次http调用。即使在发送每个请求前都有300毫秒的延迟，我们仍然可能同时拥有多个在途的HTTP请求，并且它们返回的顺序未必就是发送时的顺序。
 
       `switchMap` preserves the original request order while returning
        only the observable from the most recent http call. 
       Results from prior calls are canceled and discarded.
+      
+      `switchMap`保留了原始的请求顺序，并且只返回最近一次http调用返回的可观察对象。
+      这是因为以前的调用都被取消或丢弃了。
 
       We also short-circuit the http call and return an observable containing an empty array 
       if the search text is empty.
+      
+      如果搜索框为空，我们还可以短路掉这次http调用，并且直接返回一个包含空数组的可观察对象。
 
       Note that _canceling_ the `HeroSearchService` observable won't actually abort a pending http request
       until the service supports that feature, a topic for another day.
       We are content for now to discard unwanted results.
+      
+      注意，_取消_`HeroSearchService`的可观察对象并不会实际中止（abort）一个未完成的http请求，除非有一天我们支持了这个特性，这个问题我们以后再讨论。
+      目前我们的任务只是丢弃不希望的结果。
+      
   :marked
     * `catch` intercepts a failed observable. 
     Our simple example prints the error to the console; a real life application should do better.
     Then we return an observable containing an empty array to clear the search result.
+    
+    * `catch`拦截失败的Observable。这个简单的例子中只是把错误信息打印到控制台（但实际的应用需要做更多事），然后返回一个包含空数组的可观察对象，以清空搜索结果。
 
     ### Import RxJS operators
+    
+    ### 导入RxJS操作符
+    
     The RxJS operators are not available in Angular's base `Observable` implementation.
     We have to extend  `Observable` by *importing* them.
+    
+    Angular的基本版`Observable`实现中，RxJS操作符是不可用的。
+    我们得*导入*它们，以扩展`Observable`。
 
     We could extend `Observable` with just the operators we need here by
     including the pertinent `import` statements at the top of this file.
+    
+    通过在本文件的顶部写上适当的`import`语句，我们可以为`Observable`扩展出这里用到的那些操作符。
 
   .l-sub-section
     :marked
       Many authorities say we should do just that.
+      
+      有很多权威人士建议我们这样做。
+      
   :marked
     We take a different approach in this example. 
     We combine all of the RxJS `Observable` extensions that _our entire app_ requires into a single RxJS imports file.
+    
+    在这个例子中，我们使用一些不同的方法。
+    我们把整个应用中要用的那些RxJS `Observable`扩展组合在一起，放在一个单独的RxJS导入文件中。
 
   +makeExample('toh-6/ts/app/rxjs-extensions.ts', null, 'app/rxjs-extensions.ts')(format=".")
+  
   :marked
     We load them all at once by importing `rxjs-extensions` in `AppComponent`.
+    
+    我们在`AppComponent`中导入`rxjs-extensions`就可以一次性加载它们。
 
   +makeExample('toh-6/ts/app/app.component.ts', 'rxjs-extensions', 'app/app/app.component.ts')(format=".")  
+  
   :marked
     Finally, we add the `HeroSearchComponent` to the bottom of the `DashboardComponent`.
     Run the app again, go to the *Dashboard*, and enter some text in the search box below the hero tiles.
     At some point it might look like this.
+    
+    最后，我们把`HeroSearchComponent`添加到`DashboardComponent`的地步。
+    再次运行该应用，跳转到*Dashboard*，并在英雄下方的搜索框里输入一些文本。
+    看起来就像这样：
 
   figure.image-display
     img(src='/resources/images/devguide/toh/toh-hero-search.png' alt="Hero Search Component")