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July 12, 2024 03:28
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// Example usage | |
const data = { a: 1, b: { c: 2, d: [1, 2, 3] } }; | |
const data2 = JSON.parse(JSON.stringify(data)); | |
const proxy = createProxy(data, (diff) => { | |
applyDiff(data2, diff); | |
console.log(data2, diff); | |
}); | |
proxy.a = 2; | |
proxy.b.c = 3; | |
proxy.b.d.push(4); | |
proxy.b.d.splice(0, 1); | |
proxy.b.d = [1, 2]; | |
proxy.e = {a: 1}; | |
delete proxy.a; | |
delete proxy.b.c; | |
console.log(data, data2); |
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export const enum DiffType { | |
ADD, | |
UPDATE, | |
REMOVE | |
} | |
export type DiffPartial<T> = { | |
[P in keyof T]?: | |
T[P] extends (infer U)[] ? DiffPartial<U>[] | ({ [index: number]: DiffPartial<U> }) : | |
T[P] extends object | undefined ? DiffPartial<T[P]> : | |
T[P]; | |
}; | |
export type Diff<T> = { | |
type: DiffType, | |
value: DiffPartial<T>, | |
}; | |
export function createProxy<T extends object>(data: T, callback: (diff: Diff<T>) => void): T { | |
return new Proxy(data, { | |
set(target: T, property, value) { | |
const prevValue = target[property as keyof T]; | |
if (prevValue !== value) { | |
const diffType = (property in target) ? DiffType.UPDATE : DiffType.ADD; | |
target[property as keyof T] = value; | |
callback({type: diffType, value: {[property as keyof T]: value} as DiffPartial<T>}); | |
} | |
return true; | |
}, | |
deleteProperty(target: T, property) { | |
if (property in target) { | |
delete target[property as keyof T]; | |
callback({type: DiffType.REMOVE, value: {[property as keyof T]: undefined}} as Diff<T>); | |
} | |
return true; | |
}, | |
get(target: T, property, receiver) { | |
const prop = property as keyof T; | |
if (property === '__isProxy__') return true; | |
const value = target[prop] as T[typeof prop] & { __isProxy__: boolean }; | |
if (typeof value === 'object' && value !== null && !value.__isProxy__) { | |
return createProxy(value, (p) => { | |
callback({type: p.type, value: {[prop]: p.value} as DiffPartial<T>} as Diff<T>); | |
}); | |
} | |
return value; | |
} | |
}); | |
} | |
export function applyDiff<T>(target: T, diff: Diff<T>): void { | |
switch (diff.type) { | |
case DiffType.ADD: | |
applyAdd(target, diff.value); | |
break; | |
case DiffType.UPDATE: | |
applyPartial(target, diff.value); | |
break; | |
case DiffType.REMOVE: | |
applyRemove(target, diff.value); | |
break; | |
} | |
} | |
function applyAdd<T>(target: T, partial: DiffPartial<T>): void { | |
for (const key in partial) { | |
const value = partial[key]; | |
if (target.hasOwnProperty(key)) { | |
applyAdd(target[key], value as DiffPartial<T[keyof T]>); | |
} else if (Array.isArray(target)) { | |
(target as any[]).push(value); | |
} else { | |
target[key] = value as T[Extract<keyof T, string>]; | |
} | |
} | |
} | |
function applyPartial<T>(target: T, partial: DiffPartial<T>): void { | |
for (const key in partial) { | |
const value = partial[key]; | |
if (value && typeof value === 'object' && !Array.isArray(value)) { | |
applyPartial(target[key], value); | |
} else { | |
target[key] = value as T[Extract<keyof T, string>]; | |
} | |
} | |
} | |
function applyRemove<T>(target: T, partial: DiffPartial<T>): void { | |
for (const key in partial) { | |
const value = partial[key]; | |
if (value !== undefined) { | |
applyRemove(target[key], value as DiffPartial<T[keyof T]>); | |
} else if (target.hasOwnProperty(key)) { | |
delete target[key]; | |
} else if (Array.isArray(target)) { | |
const index = parseInt(key, 10); | |
(target as any[]).splice(index, 1); | |
} | |
} | |
} |
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