feat(express): 新增错误处理文档和demo代码

code/express/apps/error-handle-demo/app.js

@@ -0,0 +1,12 @@
+const express = require('express')
+const app = express()
+const port = 4000
+const appName = require('./package.json').name
+app.get('/', async(req, res) => {
+  console.log('请求进来了...')
+  throw new Error('手动抛错了！！')
+})
+
+app.listen(port, () => {
+  console.log(`${appName} listening on port ${port}`)
+})

code/express/apps/error-handle-demo/handle.js

@@ -0,0 +1,32 @@
+const express = require('express')
+const app = express()
+const bodyParser = require('body-parser')
+const methodOverride = require('method-override')
+const port = 4000
+app.use(bodyParser.urlencoded({
+  extended: true
+}))
+app.use(bodyParser.json())
+app.use(methodOverride())
+
+
+/**
+ * 定义一些路由逻辑
+ */
+
+app.get('/get', async(req, res) => {
+  console.log('处理业务逻辑')
+})
+
+/**
+ * 最后自定义错误处理
+ *
+ */
+app.use((err, req, res, next) => {
+  console.log('捕获到的错误信息')
+  console.log(err)
+})
+
+app.listen(port, () => {
+  console.log('app listen on：', port)
+})