1 Use in JavaScript {#flatbuffers_guide_use_javascript} 2 ================= 3 4 ## Before you get started 5 6 Before diving into the FlatBuffers usage in JavaScript, it should be noted that 7 the [Tutorial](@ref flatbuffers_guide_tutorial) page has a complete guide to 8 general FlatBuffers usage in all of the supported languages 9 (including JavaScript). This page is specifically designed to cover the nuances 10 of FlatBuffers usage in JavaScript. 11 12 You should also have read the [Building](@ref flatbuffers_guide_building) 13 documentation to build `flatc` and should be familiar with 14 [Using the schema compiler](@ref flatbuffers_guide_using_schema_compiler) and 15 [Writing a schema](@ref flatbuffers_guide_writing_schema). 16 17 ## FlatBuffers JavaScript library code location 18 19 The generated code for the FlatBuffers JavaScript library can be found at 20 https://www.npmjs.com/package/flatbuffers. To use it from sources: 21 22 1. Run `npm run compile` from the main folder to generate JS files from TS. 23 1. In your project, install it as a normal dependency, using the flatbuffers 24 folder as the source. 25 26 ## Using the FlatBuffers JavaScript library 27 28 *Note: See [Tutorial](@ref flatbuffers_guide_tutorial) for a more in-depth 29 example of how to use FlatBuffers.* 30 31 Due to the complexity related with large amounts of JS flavors and module types, 32 native JS support has been replaced in 2.0 by transpilation from TypeScript. 33 34 Please look at [TypeScript usage](@ref flatbuffers_guide_use_typescript) and 35 transpile your sources to desired JS flavor. The minimal steps to get up and 36 running with JS are: 37 38 1. Generate TS files from `*.fbs` by using the `--ts` option. 39 1. Transpile resulting TS files to desired JS flavor using `tsc` (see 40 https://www.typescriptlang.org/download for installation instructions). 41 42 ~~~{.js} 43 // Note: These require functions are an example - use your desired module flavor. 44 var fs = require('fs'); 45 46 var flatbuffers = require('../flatbuffers').flatbuffers; 47 var MyGame = require('./monster_generated').MyGame; 48 49 var data = new Uint8Array(fs.readFileSync('monster.dat')); 50 var buf = new flatbuffers.ByteBuffer(data); 51 52 var monster = MyGame.Example.Monster.getRootAsMonster(buf); 53 54 //--------------------------------------------------------------------------// 55 56 // Note: This code is an example of browser-based HTML/JavaScript. See above 57 // for the code using JavaScript module loaders (e.g. Node.js). 58 <script src="../js/flatbuffers.js"></script> 59 <script src="monster_generated.js"></script> 60 <script> 61 function readFile() { 62 var reader = new FileReader(); // This example uses the HTML5 FileReader. 63 var file = document.getElementById( 64 'file_input').files[0]; // "monster.dat" from the HTML <input> field. 65 66 reader.onload = function() { // Executes after the file is read. 67 var data = new Uint8Array(reader.result); 68 69 var buf = new flatbuffers.ByteBuffer(data); 70 71 var monster = MyGame.Example.Monster.getRootAsMonster(buf); 72 } 73 74 reader.readAsArrayBuffer(file); 75 } 76 </script> 77 78 // Open the HTML file in a browser and select "monster.dat" from with the 79 // <input> field. 80 <input type="file" id="file_input" onchange="readFile();"> 81 ~~~ 82 83 Now you can access values like this: 84 85 ~~~{.js} 86 var hp = monster.hp(); 87 var pos = monster.pos(); 88 ~~~ 89 90 ## Text parsing FlatBuffers in JavaScript 91 92 There currently is no support for parsing text (Schema's and JSON) directly 93 from JavaScript. 94