- 创建服务器
var express = require('express')
var app = express()
app.listen(3000, () => console.log('Example app listening on port 3000!'))
- 常用四种路由
app.get('/', function(req, res) {
res.send('hello world')
})
app.post('/', function(req, res) {
res.send('Got a POST request')
})
app.put('/user', function(req, res) {
res.send('Got a PUT request at /user')
})
app.delete('/user', function(req, res) {
res.send('Got a DELETE request at /user')
})
- 传参数 parameters
app.get('/users/:userId/books/:bookId', function(req, res) {
res.send(req.params)
})
- 处理器 handlers，多个事件顺序执行
var cb0 = function(req, res, next) {
console.log('CB0')
next()
}
var cb1 = function(req, res, next) {
console.log('CB1')
next()
}
var cb2 = function(req, res) {
res.send('Hello from C!')
}
app.get('/example/c', [cb0, cb1, cb2])
app.get('/example/d', [
cb0, cb1
], function(req, res, next) {
console.log('the response will be sent by the next function ...')
next()
}, function(req, res) {
res.send('Hello from D!')
})
- 中间件 function，requestTime 会传递到下文执行的 req 中
var requestTime = function(req, res, next) {
req.requestTime = Date.now()
next()
}
app.use(requestTime)
app.get('/req', function(req, res) {
var responseText = 'Hello World!<br>'
responseText += '<small>Requested at: ' + req.requestTime + '</small>'
res.send(responseText)
})
- 事件跳转
app.get('/user/:id', function(req, res, next) {
// if user ID == 0, 跳转到 next route 'special'
if (req.params.id === '0')
next('route')
// 否则执行这个栈中的下一个中间件函数'regular'
else
next()
}, function(req, res, next) {
// send a regular response
res.send('regular')
})
// handler for the /user/:id path, which sends a special response
app.get('/user/:id', function(req, res, next) {
res.send('special')
})
- 展示 html 页面
res.sendFile(__dirname + "/public/index.html");
- 展示静态文件目录
public 文件夹下的内容
app.use(express.static('public'))
app.use('/static', express.static('public'))
- 展示 json
app.get("/json", function(req, res) {
res.json({"message": "Hello World"});
});
- 错误处理
app.get("/err", function(req, res) {
throw new Error("BROKEN"); // Express will catch this on its own.
});
app.get("/not", function(req, res, next) {
fs.readFile("/file-does-not-exist", function(err, data) {
if (err) {
next(err); // Pass errors to Express.
} else {
res.send(data);
}
});
});
- 404
app.use(function(req, res, next) {
res.status(404).send("Sorry can't find that!")
})
- 500
app.use(function(err, req, res, next) {
console.error(err.stack)
res.status(500).send('Something broke!')
})
- 启动服务器
node index.js
debug 模式启动
$ DEBUG=express:* node index.js
On Windows
> set DEBUG=express:* & node index.js