Introduction to Contextify

Contextify is a powerful and flexible library that simplifies the management of dynamic contexts in JavaScript applications. It provides developers with a myriad of APIs to manipulate and control execution contexts, making it easier to implement advanced functionalities without hassle.

Getting Started with Contextify

To begin using Contextify, you need to install it via npm:

  $ npm install contextify

API Examples

1. Creating a Context

Creating a new context is simple with Contextify:

  const contextify = require('contextify');
  const context = contextify.createContext({ foo: 'bar' });

2. Running Scripts in a Context

You can run scripts within the created context using:

  context.run('foo += 1');
  console.log(context.foo);  // Output: bar1

3. Destroying a Context

To free resources, it is important to destroy a context when you no longer need it:

  context.dispose();

4. Safe Execution

Ensuring safe execution of code is a critical aspect of any scripting environment:

  context.run('while (true) {}', { timeout: 1000 }, (err) => {
    if (err) {
      console.log('Script execution timed out');
    }
  });

5. Contextify Options

Contextify supports various options to customize its behavior:

  const context = contextify.createContext({ foo: 'bar' }, { timeout: 5000 });

Application Example with Contextify

Let’s create a simple web application that uses Contextify to sandbox user code.

  const express = require('express');
  const contextify = require('contextify');
  
  const app = express();
  app.use(express.json());
  
  app.post('/execute', (req, res) => {
    const { script, context } = req.body;
    const ctx = contextify.createContext(context);
    try {
      ctx.run(script);
      res.json(ctx);
    } catch (err) {
      res.status(500).send('Script execution failed');
    } finally {
      ctx.dispose();
    }
  });
  
  app.listen(3000, () => {
    console.log('Server is running on port 3000');
  });

In this example, we create an Express server that takes JSON input containing a script and context. It runs the script safely within the provided context and returns the modified context as a response.

By mastering the Contextify library, you can add powerful scripting capabilities to your application, safely executing and managing code dynamically.

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