NodeJS class.helper module
- ES6 Class private
- Singleton pattern
node >= 6.0.0
npm install class.helper
const ClassHelper = require('class.helper');
class A extends ClassHelper {
constructor(session, defaultValue) {
super();
this.publicKey = 'public';
this.private.session = session;
this.private.defaultValue = defaultValue;
this.private.currentValue = defaultValue;
}
add() {
this.private.currentValue += 1;
}
get value() {
return this.private.currentValue;
}
get userName() {
const {session} = this.private;
return session.userName;
}
}
// express - singleton instance sharing by session container
app.use((req, res, next) => {
req.session = { // set request session container
userName: 'Jone'
};
next();
});
app.use(({session}, res, next) => {
const oA = A.getInstance(session, 1); // first instance -> create new instance A
const oB = A.getInstance(session, 1); // same arguments -> oA reference
const oC = A.getInstance(session, 2); // different arguments -> create new instance A
console.log(oA.value); // 1
console.log(oB.value); // 1
console.log(oC.value); // 2
oA.add();
oB.add();
oC.add();
console.log(oA.value); // 3
console.log(oB.value); // 3
console.log(oB.value); // 3
console.log(Object.keys(oC)); // [ 'publicKey' ] - invisible "private"
console.log(oA.userName); // Jone - public getter
console.log(oA.private.session.userName); // Jone - private access
console.log(JSON.stringify(oC)); // {"publicKey":"public"} - invisible "private"
// instances will be removed by GC after request end. Safe from memory leaks.
next();
});MIT License
Copyright (c) 2016 Bum-Seok Hwang
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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