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开源软件名称:koajs/koa开源软件地址:https://github.com/koajs/koa开源编程语言:JavaScript 100.0%开源软件介绍:Expressive HTTP middleware framework for node.js to make web applications and APIs more enjoyable to write. Koa's middleware stack flows in a stack-like manner, allowing you to perform actions downstream then filter and manipulate the response upstream. Only methods that are common to nearly all HTTP servers are integrated directly into Koa's small ~570 SLOC codebase. This includes things like content negotiation, normalization of node inconsistencies, redirection, and a few others. Koa is not bundled with any middleware. InstallationKoa requires node v7.6.0 or higher for ES2015 and async function support.
Hello Koaconst Koa = require('koa');
const app = new Koa();
// response
app.use(ctx => {
ctx.body = 'Hello Koa';
});
app.listen(3000); Getting started
MiddlewareKoa is a middleware framework that can take two different kinds of functions as middleware:
Here is an example of logger middleware with each of the different functions: async functions (node v7.6+)app.use(async (ctx, next) => {
const start = Date.now();
await next();
const ms = Date.now() - start;
console.log(`${ctx.method} ${ctx.url} - ${ms}ms`);
}); Common function// Middleware normally takes two parameters (ctx, next), ctx is the context for one request,
// next is a function that is invoked to execute the downstream middleware. It returns a Promise with a then function for running code after completion.
app.use((ctx, next) => {
const start = Date.now();
return next().then(() => {
const ms = Date.now() - start;
console.log(`${ctx.method} ${ctx.url} - ${ms}ms`);
});
}); Koa v1.x Middleware SignatureThe middleware signature changed between v1.x and v2.x. The older signature is deprecated. Old signature middleware support will be removed in v3 Please see the Migration Guide for more information on upgrading from v1.x and using v1.x middleware with v2.x. Context, Request and ResponseEach middleware receives a Koa app.use(async (ctx, next) => { await next(); }); Koa provides a Here is an example of checking that a requesting client supports xml. app.use(async (ctx, next) => {
ctx.assert(ctx.request.accepts('xml'), 406);
// equivalent to:
// if (!ctx.request.accepts('xml')) ctx.throw(406);
await next();
}); Koa provides a Koa's pattern of delegating to Node's request and response objects rather than extending them
provides a cleaner interface and reduces conflicts between different middleware and with Node
itself as well as providing better support for stream handling. The Here is an example using Koa's app.use(async (ctx, next) => {
await next();
ctx.response.type = 'xml';
ctx.response.body = fs.createReadStream('really_large.xml');
}); The For more information on Koa ApplicationThe object created when executing The application object is Koa's interface with node's http server and handles the registration of middleware, dispatching to the middleware from http, default error handling, as well as configuration of the context, request and response objects. Learn more about the application object in the Application API Reference. DocumentationTroubleshootingCheck the Troubleshooting Guide or Debugging Koa in the general Koa guide. Running tests
Reporting vulnerabilitiesTo report a security vulnerability, please do not open an issue, as this notifies attackers of the vulnerability. Instead, please email dead_horse, jonathanong, and niftylettuce to disclose. AuthorsSee AUTHORS. Community
Job BoardLooking for a career upgrade? BackersSupport us with a monthly donation and help us continue our activities. SponsorsBecome a sponsor and get your logo on our README on Github with a link to your site. License |
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