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Vue ͷϦΞΫςΟϒγεςϜ
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ࣗݾհ
• Ryota Horiguchi
• GitHub: ryotah
• merpay ϑϩϯτΤϯυΤϯδχΞ
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͢͜ͱ
• Vue ͷϦΞΫςΟϒγεςϜͷҰ෦Λઆ໌
• ϦΞΫςΟϒγεςϜ
=> Ϟσϧͷมߋ͕DOMʹө͞ΕΔΈ
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https://blog.thoughtram.io//angular/2016/02/22/
angular-2-change-detection-explained.html
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ϦΞΫςΟϒͷ୳ٻ — Vue.js
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Ұ୴αϯϓϧΛ
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ஈͱ͔Β߹ܭֹۚΛදࣔ͢ΔΞϓϦέʔγϣϯ
// js
const app = new Vue({
el: '#app',
data: {
price: 100,
quantity: 2
},
computed: {
total() { return this.price * this.quantity; }
}
});
https://stackblitz.com/edit/vue-reactivity
price: {{ price }}
quantity: {{ quantity }}
total: {{ total }}
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• data
• Vue ΠϯελϯεͷͨΊͷσʔλΦϒδΣΫτ
• Vue Πϯελϯε͕࡞͞ΕΔͱϦΞΫςΟϒ
γεςϜʹՃ͞ΕΔ
• computed
• Vue ΠϯελϯεʹΈࠐ·ΕΔࢉग़ϓϩύ
ςΟ
• ࢉग़ϓϩύςΟґଘؔʹͱ͖ͮΩϟο
γϡ͞ΕΔ
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ࠓͷΰʔϧ
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let data = { price: 100, quantity: 2 };
let total = data.price * data.quantity;
console.log(total);
// => 200
data.quantity = 3;
console.log(total);
// => 300 ?
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ͦͷ̍
ؔΛอଘ
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let data = { price: 100, quantity: 2 };
// ࠶ܭࢉͰ͖ΔΑ͏ʹؔΛอଘ
let target =
() => data.total = data.price * data.quantity;
target();
console.log(data.total);
// => 200
data.quantity = 3;
target();
console.log(data.total);
// => 300
// https://stackblitz.com/edit/vue-reactivity-step-by-step?file=step-96.js
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• อଘ͞ΕΔؔෳඞཁ
• ґଘؔͷ͋Δ͚ؔͩΛཧ͍ͨ͠
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ͦͷ̎
Dependency Class
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export let target = null;
export class Dep {
constructor() {
this.subscribers= [];
}
depend() {
if (target && !this.subscribers.includes(target)) {
this.subscribers.push(target);
}
}
notify() {
this.subscribers.forEach(sub => sub());
}
}
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let data = { price: 100, quantity: 2 };
let watcher =
() => data.total = data.price * data.quantity;
const dep = new Dep();
target = watcher;
dep.depend();
target();
target = null;
console.log(data.total);
// => 200
data.quantity = 3;
dep.notify();
console.log(data.total);
// => 300
// https://stackblitz.com/edit/vue-reactivity-step-by-step?file=step-97.js
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Dependency Class ͷׂ
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https://medium.com/vue-mastery/the-best-
explanation-of-javascript-reactivity-fea6112dd80d
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https://medium.com/vue-mastery/the-best-
explanation-of-javascript-reactivity-fea6112dd80d
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https://medium.com/vue-mastery/the-best-
explanation-of-javascript-reactivity-fea6112dd80d
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• ϓϩύςΟ͝ͱʹ Dep Πϯελϯε͕ඞཁ
• ґଘؔͷ͋Δ͚ؔͩΛཧ͍ͨ͠
• ʢະղܾʣ
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ͦͷ̏
Object.defineProperty
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Object.keys(data).forEach(key => {
let _value = data[key];
Object.defineProperty(data, key, {
get() {
console.log('get', key, _value);
return _value;
},
set(value) {
console.log('set', key, _value);
_value = value;
}
});
});
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Object.keys(data).forEach(key => {
let _value = data[key];
const dep = new Dep();
Object.defineProperty(data, key, {
get() {
dep.depend();
return _value;
},
set(value) {
_value = value;
dep.notify();
}
});
});
// ...
target = watcher;
target();
target = null;
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console.log(data.total);
// => 200
data.quantity = 3;
console.log(data.total);
// => 300
https://stackblitz.com/edit/vue-reactivity-step-by-
step?file=step-99.js
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https://medium.com/vue-mastery/the-best-
explanation-of-javascript-reactivity-fea6112dd80d
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ৼΓฦΓ
• Vue ͷϦΞΫςΟϒγεςϜͷҰ෦Λઆ໌
• Object.defineProperty
• Dep class
• Watcher
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ࢀߟࢿྉ
• The Best Explanation of JavaScript Reactivity –
Vue Mastery – Medium
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͝੩ௌ͋Γ͕ͱ͏͍͟͝·
ͨ͠
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͓·͚̍
Angular ͷ߹
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export class AppComponent {
price: number;
quantity: number;
constructor() {
this.price = 100;
this.quantity = 2;
(window as any).app = this;
}
get total() {
return this.price * this.quantity;
}
}
// ίϯιʔϧ͔Β࣮ߦ
window.app.quantity = 10;
// => DOMߋ৽͞Εͳ͍
// => ϘλϯΫϦοΫͳͲΛ͢Δͱө͞ΕΔ
https://stackblitz.com/edit/vue-reactivity-case-of-
angular
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Angular ͷϨϯμϦϯάʹڵຯ͕͋Δํ
ຊޠ༁ Angular 2 Change Detection Explained |
͕͓͢͢ΊͰ͢
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͓·͚̎
Vue Πϯελϯε࡞࣌ͷ࣮ࡍͷ
ίʔυΛͬͯΈΔ
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instance/index
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/index.js#L8
function Vue (options) {
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/index.js#L14
this._init(options)
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instance/init
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/init.js#L16
Vue.prototype._init = function
(options?: Object) {
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/init.js#L57
initState(vm)
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instance/state
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/state.js#L48
export function initState (vm:
Component) {
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/state.js#L54
initData(vm)
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/state.js#L112
function initData (vm: Component) {
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• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/instance/state.js#L151
observe(data, true /* asRootData */)
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observer/index
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js
export function observe (value: any,
asRootData: ?boolean): Observer |
void {
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js#L123
ob = new Observer(value)
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js#L37
export class Observer {
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• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js#L66
defineReactive(obj, keys[i])
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js#L134
export function defineReactive (
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js#L156
Object.defineProperty(obj, key, {
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• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js#L162
dep.depend()
• https://github.com/vuejs/vue/blob/v2.5.17/src/
core/observer/index.js#L188
dep.notify()