Native JSON Support in AIR 3

One of the many new features in AIR 3 (in beta, available on Adobe Labs) is the new native JSON parser. It has always been possible to parse JSON with ActionScript, but AIR 3 provides native JSON support which is faster than ActionScript implementations, and more efficient in terms of memory usage.

The two main things the JSON class can do are:

  1. Parse JSON strings.
  2. Turn ActionScript objects into JSON ("stringify").

To learn more about JSON support in AIR 3, check out this short sample news reader (you can also download the FXP file) which uses JSON rather than RSS. The code is so simple, I’ll include the entire thing below:

<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="" xmlns:s="library://" xmlns:mx=" library://" applicationComplete="onApplicationComplete();">


      import flash.globalization.DateTimeFormatter;
      import flash.globalization.DateTimeStyle;
      import flash.globalization.LocaleID;


      private var df:DateTimeFormatter;

      private function onApplicationComplete():void
        // Feed data is stored as a JSON file...
        var f:File = File.applicationDirectory.resolvePath("feeds.json");
        var fs:FileStream = new FileStream();, FileMode.READ);
        var feedJson:String = fs.readUTFBytes(fs.bytesAvailable);
        var feeds:Object = JSON.parse(feedJson);
        this.feedTree.dataProvider = feeds;
        this.postHtmlContainer.htmlLoader.navigateInSystemBrowser = true;
        df = new DateTimeFormatter(LocaleID.DEFAULT, DateTimeStyle.MEDIUM, DateTimeStyle.NONE);

      private function onTreeClick(e:MouseEvent):void
        if (!this.feedTree.selectedItem || ! return;

      private function onFeedLoaded(e:ResultEvent):void
        var result:String = e.result.toString();
        var feedData:Object = JSON.parse(result);
        var s:String = '<html><body>';
        s += '<h1>Posts for ' + feedData.responseData.feed.title + '</h1>';
        for each (var post:Object in feedData.responseData.feed.entries)
          s += '<p class="postTitle"><a href="' + + '">' + post.title + '&nbsp;&nbsp;&#0187;</a></p>';
          s += '<p>' + df.format(new Date(post.publishedDate)) + '</p>';
          s += '<p>' + post.content + '</p><hr/>';
        s += '</body></html>';
        this.postHtmlContainer.htmlText = s;


    <s:HTTPService id="feedService" url="" result="onFeedLoaded(event)" resultFormat="text" contentType="application/x-www-form-urlencoded" method="GET" showBusyCursor="true" />

  <mx:HDividedBox width="100%" height="100%">
    <mx:Tree id="feedTree" width="200" height="100%" click="onTreeClick(event);"/>
    <mx:HTML width="100%" height="100%" id="postHtmlContainer"/>

Keep in mind that AIR 3 is still in beta, so you might find bugs. If you do, here’s how to file them.

20 Responses to Native JSON Support in AIR 3

  1. michael says:

    Nice, but I wonder why it’s in AIR only.

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  4. Vic says:

    I wonder why not BSON.

  5. sascha/hdrs says:

    @Vic It was named after Jason from Friday The 13th! o_O

    If it comes to Flash Player that is good to hear! Because otherwise there’s a name conflict with the adobe corelib one right now that gives you compile-time errors.

  6. First, apologies for cross posting this (I originally added a comment on your Google+ post), but I figure this is the more appropriate spot…

    Hi Christian, I am trying to use native JSON with Air 3 RC1. I am able to compile against the SDK no problem, but at runtime I get: “ReferenceError: Error #1065: Variable JSON is not defined.” I triple checked that I am using the correct SDK, and stragely FlashBuilder recognizes and code-hints “JSON” when referenced in the IDE. Any ideas? Do I need to add a compilation flag for the Flex compiler or something?

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  8. Craig says:

    I also get a “Error #1065: Variable JSON is not defined.” in runtime.

  9. Craig says:

    Here’s the solution to get JSON working in Adobe Air 3 projects:

    “Hi,guys,at last i found the solution in the post “ beta-sdk.html” 。Just go to “Project Properties,” then “Flex Compiler.” In the “Additional compiler arguments” box, add “-swf-version=13″ (13 represents air3)”

  10. e-liquid says:

    I also get a “Error #1065 too

  11. Usach says:

    Native JSON – is very good. BUT for me very critical backward compatibility with old versions of AIR and FLEX sdk’s. At the moment I’ve got errors like
    Error: Can not resolve a multiname reference unambiguously. JSON (from …\frameworks\libs\air\airglobal.swc(JSON, Walker)) and com.adobe.serialization.json:JSON (from ..\src\com\adobe\serialization\json\ are available.
    How should I resolve it?

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  13. indirmp3 says:

    gör bak nası döwüyom

  14. bisteck says:

    I had to download the latest version of the Flex SDK (4.6) from here:

    Then right click on the project, go to properties, then go to Flex Compiler and set the SDK to 4.6.

    Then I had to change this tag in the application manifest from:


    No errors after that. I kinda like Flex / Air / Flash Builder, but documentation needs a lot more work. Adobe should take PHP’s documentation website as an example.

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  16. You can find here a solution that compiles for both version of player, using internal JSON when available.
    It compiles transparently without triggering any error:

  17. muni says:

    Find the solution for thr error Cannot Resolve a Multiname Reference Unambiguously JSON
    in the following URL