Book Image

Opa Application Development

By : Li Wenbo
Book Image

Opa Application Development

By: Li Wenbo

Overview of this book

Opa is a full-stack Open Source web development framework for JavaScript that lets you write secure and scalable web applications. It generates standard Node.js/MongoDB applications, natively supports HTML5 and CSS and automates many aspects of modern web application programming. It handles all aspects of web programming written in one consistent language and compiled to web standards.Opa Application Development is a practical,hands-on guide that provides you with a number of step-by-step exercises. It covers almost all aspects of developing a web application with Opa, which will help you take advantage of the real power of Opa, as well as building a secure, powerful web application rapidly.Opa Application Development dives into all concepts and components required to build a web application with Opa. The first half of this book shows you all of the basic building blocks that you will need to develop an Opa application, including the syntax of Opa, web development aspects, client and server communication and slicing, plugin, database, and so on. By the end of the book you will have yourself created a complete web application along with a game: Pacman!
Table of Contents (18 chapters)
Opa Application Development
About the Author
About the Reviewers

Internal approach

Opa now provides support for translation by means of the @i18n directive. We can put a translation function inside the @i18n directive, and it will be replaced by a proper value according to different languages. An example is worth a thousand words, so let's get started with a simple example:

import stdlib.web.client
hello = function {
  case "en": "Hello"
  case "fr": "Bonjour"
  case "zh": "你好"
  default: "Hi"
function page(){
  <h1> {@i18n(hello)} </h1>
  <input type="button" value="English" onclick={set_lang("en")}/>
  <input type="button" value="French"  onclick={set_lang("fr")}/>
  <input type="button" value="Chinese" onclick={set_lang("zh")}/>
function set_lang(lang)(_){
Server.start(Server.http, {title:"Opa Packt", ~page})

Save this code into a file, 801.opa, then compile and run it with the following command:

opa 801.opa --

The result looks as shown in the following screenshot:

The page shows...