- http server + request router + request handler
- use DI everywhere, pass router/handler as parameter to server
- no 'return' is used, use async function, 'response' object is passed all the way to handler
- in node, any async function accepts a callback as the last parameter
- in node, any callback function accepts an error as the first parameter
2. even loop
- timer: execute timer callbacks
- pending callbacks: execute I/O callbacks
- poll: incoming I/O events and callbacks
3. npm config file
- ~/.npmrc
4. module.export and require
- module.export return an object
- require use the object
require('./app/routes')(app, {}); // file2.js
5. node/nvm commands
- node -v
- nvm --version
- nvm ls-remote
- nvm install x.x.x
- nvm uninstall x.x.x
- nvm use x.x.x
- nvm use node //switch to latest
- nvm list
- nvm install --lts //install latest
- npm install -d //--loglevel info
- npm install jsonpath --save-dev //save it in package.json
- npm install -D jsonpath //-D is same as --save-dev
- npm init //new node app, generate package.json
- node hello.js
6. node app config file
- ./config by default
- can be overwritten: process.env["NODE_CONFIG_DIR"] = __dirname + "/configDir/";
7. commonly lodash functions
- .find()
8. returning everything as objects of functions
const retryCounter = () => {
let retryCounter = 0
const totalRetry = 10 //config.get('errorHandler.retryTotal')
return {
retryTotal: () => {
return totalRetry
},
count: () => {
return retryCounter
},
add: () => {
retryCounter += 1
}
}
}
9. print stack trace
- console.trace("Here I am!")
- package.json overrule the package-lock.json if package.json has been updated
- 'npm install' sometimes does not update package-lock.json, better to use 'npm update'
- version in package.json
1.0.2
~1.0.2 means to install version 1.0.2 or the latest patch version such as 1.0.4
^1.0.2 means to install version 1.0.2 or the latest minor or patch version such as 1.1.0
11. dependencies vs devDependencies
- dependencies is installed when using 'npm install' or 'npm install $package'
- devDependencies is installed when using 'npm install' or 'npm install --save-dev $package'
- dependencies is needed to run a package
- devDependencies is need to develop a package
reference
