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c-good.js
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98 lines (83 loc) · 2.54 KB
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'use strict';
function Transaction() {}
Transaction.start = (data) => {
console.log('start transaction');
const events = { commit: [], rollback: [], timeout: [], change: [] };
let delta = {};
const methods = {
commit: () => {
console.log('commit transaction');
Object.assign(data, delta);
delta = {};
},
rollback: () => {
console.log('rollback transaction');
delta = {};
},
clone: () => {
console.log('clone transaction');
const cloned = Transaction.start(data);
Object.assign(cloned.delta, delta);
return cloned;
},
delta: () => delta,
on: (name, callback) => {
const event = events[name];
if (event) event.push(callback);
},
};
const getKeys = () => {
const changes = Object.keys(delta);
const keys = Object.keys(data).concat(changes);
return keys.filter((x, i, a) => a.indexOf(x) === i);
};
const proxy = new Proxy(data, {
get(target, key) {
if (key === Symbol.iterator) return getKeys()[key]();
if (Object.hasOwn(methods, key)) return methods[key];
if (Object.hasOwn(delta, key)) return delta[key];
return target[key];
},
ownKeys() {
return getKeys();
},
getOwnPropertyDescriptor: (target, key) =>
Object.getOwnPropertyDescriptor(
Object.hasOwn(delta, key) ? delta : target,
key,
),
set(target, key, val) {
console.log('set', key, val);
if (target[key] === val) delete delta[key];
else delta[key] = val;
return true;
},
});
return proxy;
};
// Usage
const data = { name: 'Marcus Aurelius', born: 121 };
const transaction = Transaction.start(data);
console.log('data', JSON.stringify(data));
console.log('transaction', JSON.stringify(transaction));
transaction.name = 'Mao Zedong';
transaction.born = 1893;
transaction.city = 'Shaoshan';
console.log('\noutput with JSON.stringify:');
console.log('data', JSON.stringify(data));
console.log('transaction', JSON.stringify(transaction));
console.log('\noutput with console.dir:');
console.dir({ transaction });
console.log('\noutput with for-in:');
for (const key in transaction) {
console.log(key, transaction[key]);
}
transaction.commit();
console.log('data', JSON.stringify(data));
console.log('transaction', JSON.stringify(transaction));
transaction.born = 1976;
console.log('data', JSON.stringify(data));
console.log('transaction', JSON.stringify(transaction));
transaction.rollback();
console.log('data', JSON.stringify(data));
console.log('transaction', JSON.stringify(transaction));