add flatbuffers

commit 6da1cf79d90eb242e7da5318241d42279a3df3ba
Author: Max Burke <max@urbanlogiq.com>
Date:   Sun Jan 19 14:47:28 2020 -0800

    [rust] Add use declarations to Rust-generated bindings for imported FB definitions (#5645)

    * Bugfix for Rust generation of union fields named with language keywords

flatbuffers/docs/source/JavaScriptUsage.md

@@ -0,0 +1,105 @@
+Use in JavaScript    {#flatbuffers_guide_use_javascript}
+=================
+
+## Before you get started
+
+Before diving into the FlatBuffers usage in JavaScript, it should be noted that
+the [Tutorial](@ref flatbuffers_guide_tutorial) page has a complete guide to
+general FlatBuffers usage in all of the supported languages
+(including JavaScript). This page is specifically designed to cover the nuances
+of FlatBuffers usage in JavaScript.
+
+You should also have read the [Building](@ref flatbuffers_guide_building)
+documentation to build `flatc` and should be familiar with
+[Using the schema compiler](@ref flatbuffers_guide_using_schema_compiler) and
+[Writing a schema](@ref flatbuffers_guide_writing_schema).
+
+## FlatBuffers JavaScript library code location
+
+The code for the FlatBuffers JavaScript library can be found at
+`flatbuffers/js`. You can browse the library code on the [FlatBuffers
+GitHub page](https://github.com/google/flatbuffers/tree/master/js).
+
+## Testing the FlatBuffers JavaScript library
+
+The code to test the JavaScript library can be found at `flatbuffers/tests`.
+The test code itself is located in [JavaScriptTest.js](https://github.com/
+google/flatbuffers/blob/master/tests/JavaScriptTest.js).
+
+To run the tests, use the [JavaScriptTest.sh](https://github.com/google/
+flatbuffers/blob/master/tests/JavaScriptTest.sh) shell script.
+
+*Note: The JavaScript test file requires [Node.js](https://nodejs.org/en/).*
+
+## Using the FlatBuffers JavaScript libary
+
+*Note: See [Tutorial](@ref flatbuffers_guide_tutorial) for a more in-depth
+example of how to use FlatBuffers in JavaScript.*
+
+FlatBuffers supports both reading and writing FlatBuffers in JavaScript.
+
+To use FlatBuffers in your own code, first generate JavaScript classes from your
+schema with the `--js` option to `flatc`. Then you can include both FlatBuffers
+and the generated code to read or write a FlatBuffer.
+
+For example, here is how you would read a FlatBuffer binary file in Javascript:
+First, include the library and generated code. Then read the file into an
+`Uint8Array`. Make a `flatbuffers.ByteBuffer` out of the `Uint8Array`, and pass
+the ByteBuffer to the `getRootAsMonster` function.
+
+*Note: Both JavaScript module loaders (e.g. Node.js) and browser-based
+HTML/JavaScript code segments are shown below in the following snippet:*
+
+~~~{.js}
+  // Note: These require functions are specific to JavaScript module loaders
+  //       (namely, Node.js). See below for a browser-based example.
+  var fs = require('fs');
+
+  var flatbuffers = require('../flatbuffers').flatbuffers;
+  var MyGame = require('./monster_generated').MyGame;
+
+  var data = new Uint8Array(fs.readFileSync('monster.dat'));
+  var buf = new flatbuffers.ByteBuffer(data);
+
+  var monster = MyGame.Example.Monster.getRootAsMonster(buf);
+
+  //--------------------------------------------------------------------------//
+
+  // Note: This code is specific to browser-based HTML/JavaScript. See above
+  //       for the code using JavaScript module loaders (e.g. Node.js).
+  <script src="../js/flatbuffers.js"></script>
+  <script src="monster_generated.js"></script>
+  <script>
+    function readFile() {
+      var reader = new FileReader(); // This example uses the HTML5 FileReader.
+      var file = document.getElementById(
+          'file_input').files[0]; // "monster.dat" from the HTML <input> field.
+
+      reader.onload = function() { // Executes after the file is read.
+        var data = new Uint8Array(reader.result);
+
+        var buf = new flatbuffers.ByteBuffer(data);
+
+        var monster = MyGame.Example.Monster.getRootAsMonster(buf);
+      }
+
+      reader.readAsArrayBuffer(file);
+    }
+  </script>
+
+  // Open the HTML file in a browser and select "monster.dat" from with the
+  // <input> field.
+  <input type="file" id="file_input" onchange="readFile();">
+~~~
+
+Now you can access values like this:
+
+~~~{.js}
+  var hp = monster.hp();
+  var pos = monster.pos();
+~~~
+
+## Text parsing FlatBuffers in JavaScript
+
+There currently is no support for parsing text (Schema's and JSON) directly
+from JavaScript.