Context

Context is an object which contains the parsed data from the current request.

This object is passed in the request handler as an argument.

// Here we return the path
app.get('/context', (ctx) => ctx.body(ctx.path));

Path

The context includes the parsed request pathname and the start and end indices of the pathname.

// The full url is http://localhost:3000/context/middle/end
// The path starts at 21 and ends at 40
// So the full sentence should be: "Hey, these are the path, start of the path and the end of it: /context/middle/end, 21, 40"
app.get('/context/middle/end', (ctx) => ctx.body(
    `Hey, these are the path, start of the path and the end of it: ${ctx.path}, ${ctx.pathStart}, ${ctx.pathEnd}`
));

Parameters

The context includes parsed parameters from the request URL.

// Upon visiting http://localhost:3000/context/parameters/apple
// We get back: "This is a parameter: apple"
app.get(
    '/context/parameters/:name',
    (ctx) => ctx.body(`This is a parameter: ${ctx.params.name}`)
);

Request

The context includes the original Request object.

// To see a visible response, send a POST request to http://localhost:3000/context/request
// We will send the following JSON: {"message":"Hey"}
// The response should be the exact same JSON returned
app.post(
    '/context/request',
    async (ctx) => ctx.json(await ctx.req.json())
);

Response methods

The context includes methods to return a response object.

// Send a response with the provided BodyInit (text, streams, typed arrays, ...)
ctx.body('Hi');

// Shorthand of `ctx.body(null)` - return a response with empty body
ctx.end();

// Send HTML response
ctx.html('<p>Hi</p>');

// Send JSON payload
ctx.json({ hello: 'world' });

// Redirection (statusCode can be 301, 302, 307 or 308)
ctx.redirect(location, statusCode);

You can add headers, set the status code and text of the response:

app.get('/context/headers/and/status', (ctx) => {
    // Set the status
    ctx.status = 200;

    // Add a new header key-value pair
    ctx.headers.push(['X-Powered-By', 'byte']);

    // Send back response with headers and status code
    return ctx.html('<h1>Hi</h1>');
});