git clone https://github.com/Reactive-Extensions/rxjs-jquery.git cd ./rxjs-jquery
npm install rx-jquery
bower install rxjs-jquery
jam install rx-jquery
PM> Install-Package RxJS-Bridges-jQuery
We'll start out with a basic skeleton for our application with script references to jQuery, RxJS, RxJS Time-based methods, and the RxJS Bindings for jQuery, along with a textbox for input and a list for our results.
The goal here is to take the input from our textbox and throttle it in a way that it doesn't overload the service with requests. To do that, we'll get the reference to the textInput using jQuery, then bind to the 'keyup' event using the keyupAsObservable method which then takes the jQuery object and transforms it into an RxJS Observable.
var throttledInput = $'#textInput'keyupAsObservable
Since we're only interested in the text, we'll use the
map method to take the event object and return the target's value.
We're also not interested in query terms less than two letters, so we'll trim that user input by using the
filter method returning whether the string length is appropriate.
filterreturn textlength > 2;
We also want to slow down the user input a little bit so that the external service won't be flooded with requests. To do that, we'll use the
throttle method with a timeout of 500 milliseconds, which will ignore your fast typing and only return a value after you have paused for that time span.
throttle500 /* ms */
Lastly, we only want distinct values in our input stream, so we can ignore requests that are not unique, for example if I copy and paste the same value twice, the request will be ignored.
Putting it all together, our throttledInput looks like the following:
var throttledInput = $'#textInput'keyupAsObservablemapreturn $evtargetval;filterreturn textlength > 2;throttle500distinctUntilChanged;
Now that we have the throttled input from the textbox, we need to query our service, in this case, the Wikipedia API, for suggestions based upon our input. To do this, we'll create a function called searchWikipedia which calls the jQuery.ajaxAsObservable method which wraps the existing jQuery Ajax request in an
return $ajaxAsObservableurl: ''data: action: 'opensearch'search: termformat: 'json'dataType: 'jsonp';
Now that the Wikipedia Search has been wrapped, we can tie together throttled input and our service call. Finally, to deal with concurrency issues, we'll need to ensure we're getting only the latest value. Issues can arise with asynchronous programming where an earlier value, if not cancelled properly, can be returned before the latest value is returned, thus causing bugs. To ensure that this doesn't happen, we have the
flatMap method which returns only the latest value.
var suggestions = throttledInputflatMapLatestreturn searchWikipediatext;;
Finally, we'll subscribe to our observable by calling subscribe which will receive the results and put them into an unordered list. We'll also handle errors, for example if the server is unavailable by passing in a second function which handles the errors.
var selector = $'#results';var subscription = suggestionssubscribeselectorclear;$eachdata1$'<li>' + text + '</li>'appendToselector;;selectorclear;$'<li>Error: ' + e + '</li>'appendTo'#results';;
We've only scratched the surface of this library in this simple example.
jQuery Event Shortcuts
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