flatbuffers-bigfoot/docs/source/TypeScriptUsage.md

Use in TypeScript

Before you get started

Before diving into the FlatBuffers usage in TypeScript, 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 TypeScript). This page is specifically designed to cover the nuances of FlatBuffers usage in TypeScript.

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 TypeScript library code location

The code for the FlatBuffers TypeScript library can be found at flatbuffers/js with typings available at @types/flatbuffers.

Testing the FlatBuffers TypeScript library

To run the tests, use the [TypeScriptTest.sh](https://github.com/google/ flatbuffers/blob/master/tests/TypeScriptTest.sh) shell script.

Note: The TypeScript test file requires Node.js.

Using the FlatBuffers TypeScript libary

Note: See [Tutorial](@ref flatbuffers_guide_tutorial) for a more in-depth example of how to use FlatBuffers in TypeScript.

FlatBuffers supports both reading and writing FlatBuffers in TypeScript.

To use FlatBuffers in your own code, first generate TypeScript classes from your schema with the --ts 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 TypeScript: 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: import flatbuffers with your desired import method

  import { MyGame } from './monster_generated';

  let data = new Uint8Array(fs.readFileSync('monster.dat'));
  let buf = new flatbuffers.ByteBuffer(data);

  let monster = MyGame.Example.Monster.getRootAsMonster(buf);

Now you can access values like this:

  let hp = monster.hp();
  let pos = monster.pos();

Object based API

FlatBuffers is all about memory efficiency, which is why its base API is written around using as little as possible of it. This does make the API clumsier (requiring pre-order construction of all data, and making mutation harder).

For times when efficiency is less important a more convenient object based API can be used (through --gen-object-api) that is able to unpack & pack a FlatBuffer into objects and standard TS types.

When using the obj based API, the flatbuffers import need to be in the global namespace if you don't have --no-fb-import enabled since creating default values require accessing the flatbuffers.js file.

To use:

    // Autogenerated class from table Monster.
    let monsterobj = new MonsterT();

    // Deserialize from buffer into object.
    Monster.getRootAsMonster(flatbuffer).unpackTo(monsterobj);
    // or
    let monsterobj = Monster.getRootAsMonster(flatbuffer).unpack();

    // Update object directly like a regular TS class instance.
    console.log(monsterobj.name);
    monsterobj.name = "Bob";

    // Serialize into new flatbuffer.
    let fbb = new flatbuffers.Builder(1);
    Monster.finishMonsterBuffer(fbb, monsterobj.pack(fbb));

Text parsing FlatBuffers in TypeScript

There currently is no support for parsing text (Schema's and JSON) directly from TypeScript.