写一个Mini-vue
包含：reactive、ref、effect、VNode + h、简易 renderer（patch）、component 支持 以及一个 非常小型的 template-compiler（支持标签、文本、 插值、基本属性与 @event 绑定）。
说明：这个实现尽量短小清晰，便于阅读与扩展；不是生产级，但足够展示核心原理并用于实验与学习。
# Mini-Vue：单文件实现（复制粘贴到浏览器控制台或在网页中运行）
<!-- 把这一整段放到一个 HTML 文件里，打开即可看到 demo -->
<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<title>mini-vue demo</title>
</head>
<body>
<div id="app"></div>
<script>
/* ---------------------------
reactivity: effect / track / trigger / reactive / ref
--------------------------- */
let activeEffect = null
const targetMap = new WeakMap()
function effect(fn, options = {}) {
const effectFn = () => {
try {
activeEffect = effectFn
return fn()
} finally {
activeEffect = null
}
}
effectFn.scheduler = options.scheduler
if (!options.lazy) effectFn()
return effectFn
}
function track(target, key) {
if (!activeEffect) return
let depsMap = targetMap.get(target)
if (!depsMap) targetMap.set(target, (depsMap = new Map()))
let dep = depsMap.get(key)
if (!dep) depsMap.set(key, (dep = new Set()))
dep.add(activeEffect)
}
function trigger(target, key) {
const depsMap = targetMap.get(target)
if (!depsMap) return
const dep = depsMap.get(key)
if (!dep) return
const effects = new Set(dep)
effects.forEach(eff => {
if (eff.scheduler) eff.scheduler(eff)
else eff()
})
}
function reactive(target) {
if (typeof target !== 'object' || target === null) return target
return new Proxy(target, {
get(t, k, r) {
const res = Reflect.get(t, k, r)
track(t, k)
return typeof res === 'object' && res !== null ? reactive(res) : res
},
set(t, k, v, r) {
const old = t[k]
const result = Reflect.set(t, k, v, r)
if (old !== v) trigger(t, k)
return result
},
deleteProperty(t, k) {
const had = k in t
const result = Reflect.deleteProperty(t, k)
if (had && result) trigger(t, k)
return result
}
})
}
function ref(raw) {
const r = {
__isRef: true,
get value() {
track(r, 'value')
return raw
},
set value(v) {
raw = v
trigger(r, 'value')
}
}
return r
}
/* ---------------------------
VNode + h helper
--------------------------- */
function h(type, props = null, children = null) {
return { type, props, children, el: null }
}
const TEXT = Symbol('text')
function createTextVNode(text) {
return { type: TEXT, props: null, children: String(text), el: null }
}
/* ---------------------------
Simple template compiler
- Uses a <template> element to parse HTML (works in browsers)
- Supports:
- elements with attributes (attr="value")
- event attrs like @click => props.onClick
- text nodes with {{ expr }} interpolation (evaluated against _ctx)
- Returns a render function: (ctx) => vnode
NOTE: This is intentionally tiny and not fully featured.
--------------------------- */
function compileTemplate(template) {
const tplRoot = document.createElement('template')
tplRoot.innerHTML = template.trim()
const parseNode = (node) => {
if (node.nodeType === Node.TEXT_NODE) {
const raw = node.textContent
const tokens = []
let lastIndex = 0
const re = /{{([^}]+)}}/g
let match
while ((match = re.exec(raw)) !== null) {
const index = match.index
if (index > lastIndex) {
tokens.push(JSON.stringify(raw.slice(lastIndex, index)))
}
tokens.push(`(${match[1].trim()})`)
lastIndex = index + match[0].length
}
if (lastIndex < raw.length) {
tokens.push(JSON.stringify(raw.slice(lastIndex)))
}
if (tokens.length === 0) return null
const code = tokens.join(' + ')
// create a function that returns a text vnode
return {
type: TEXT,
renderCode: `createTextVNode(${code})`
}
} else if (node.nodeType === Node.ELEMENT_NODE) {
const tag = node.tagName.toLowerCase()
// attributes
const attrs = []
const propsCode = []
for (let i = 0; i < node.attributes.length; i++) {
const a = node.attributes[i]
if (a.name.startsWith('@')) {
// event
const eventName = 'on' + a.name.slice(1)[0].toUpperCase() + a.name.slice(2)
propsCode.push(`${JSON.stringify(eventName)}: _ctx.${a.value}`)
} else {
propsCode.push(`${JSON.stringify(a.name)}: ${JSON.stringify(a.value)}`)
}
}
const children = []
node.childNodes.forEach(n => {
const parsed = parseNode(n)
if (parsed) children.push(parsed)
})
return {
type: 'element',
tag,
propsCode,
children
}
}
return null
}
const bodyNodes = []
tplRoot.content.childNodes.forEach(n => {
const parsed = parseNode(n)
if (parsed) bodyNodes.push(parsed)
})
// generate render function code
function genNodeCode(n) {
if (n.type === TEXT) return n.renderCode
if (n.type === 'element') {
const props = n.propsCode.length ? `{ ${n.propsCode.join(', ')} }` : 'null'
const kids = n.children.length
? `[${n.children.map(c => genNodeCode(c)).join(', ')}]`
: 'null'
return `h(${JSON.stringify(n.tag)}, ${props}, ${kids})`
}
return 'null'
}
const rootCode = bodyNodes.length === 1
? genNodeCode(bodyNodes[0])
: `[${bodyNodes.map(n => genNodeCode(n)).join(', ')}]`
const fnCode = `
return function render(_ctx) {
const { h, createTextVNode } = runtimeHelpers;
return ${rootCode};
}
`
// runtimeHelpers will be injected when calling the function
const renderFactory = new Function('runtimeHelpers', fnCode)
return (helpers) => renderFactory(helpers)
}
/* ---------------------------
Renderer / patch (very small)
- mountElement
- patchElement (naive)
- component mounting (setup + render effect)
--------------------------- */
function createRenderer() {
function setProps(el, oldProps = {}, newProps = {}) {
// remove old
for (const key in oldProps) {
if (!(key in newProps)) {
if (key.startsWith('on')) {
el[key.toLowerCase()] = null
} else {
el.removeAttribute(key)
}
}
}
for (const key in newProps) {
const val = newProps[key]
if (key.startsWith('on') && typeof val === 'function') {
// simple event assignment
const evt = key.toLowerCase()
el[evt] = val
} else {
el.setAttribute(key, val)
}
}
}
function mountElement(vnode, container) {
const el = document.createElement(vnode.type)
vnode.el = el
const { props, children } = vnode
if (props) {
setProps(el, {}, props)
}
if (Array.isArray(children)) {
children.forEach(child => {
patch(null, child, el)
})
} else if (children != null) {
const text = typeof children === 'string' ? children : String(children)
el.appendChild(document.createTextNode(text))
}
container.appendChild(el)
}
function patchElement(n1, n2, container) {
const el = (n2.el = n1.el)
// props
setProps(el, n1.props || {}, n2.props || {})
// children (naive)
const c1 = n1.children
const c2 = n2.children
if (Array.isArray(c2)) {
// simple strategy: clear and re-mount
el.innerHTML = ''
c2.forEach(child => patch(null, child, el))
} else if (typeof c2 === 'string' || typeof c2 === 'number') {
if (c1 !== c2) el.textContent = c2
} else {
el.textContent = ''
}
}
function mountComponent(vnode, container) {
const instance = {
vnode,
type: vnode.type,
props: vnode.props || {},
setupState: {},
isMounted: false,
subTree: null,
update: null,
}
const Component = vnode.type
// setup
let ctx = {}
if (Component.setup) {
const setupResult = Component.setup(instance.props || {}, { emit: () => {} })
if (typeof setupResult === 'function') {
// setup returned render
instance.render = setupResult
} else {
instance.setupState = setupResult || {}
}
}
// template compile if no render but template exists
if (!instance.render && Component.template) {
const renderFactory = compileTemplate(Component.template)
instance.render = renderFactory({ h, createTextVNode: createTextVNode })
}
if (!instance.render && Component.render) {
instance.render = Component.render
}
function componentUpdate() {
if (!instance.isMounted) {
// initial mount
const subTree = instance.render(instance.setupState)
instance.subTree = subTree
patch(null, subTree, container)
instance.isMounted = true
vnode.el = subTree.el
} else {
// update
const newSubTree = instance.render(instance.setupState)
patch(instance.subTree, newSubTree, container)
instance.subTree = newSubTree
vnode.el = newSubTree.el
}
}
instance.update = effect(componentUpdate, {
scheduler(fn) { // queue via microtask to batch
Promise.resolve().then(fn)
}
})
}
function patch(n1, n2, container) {
// n1 为旧 vnode, n2 新 vnode
if (n1 === n2) return
if (n1 && n1.type !== n2.type) {
// replace
const anchor = n1.el && n1.el.nextSibling
if (n1.el && n1.el.parentNode) {
n1.el.parentNode.removeChild(n1.el)
}
n1 = null
}
if (n2.type === TEXT) {
// text node
if (!n1) {
const el = document.createTextNode(n2.children)
n2.el = el
container.appendChild(el)
} else {
const el = n2.el = n1.el
if (n2.children !== n1.children) {
el.textContent = n2.children
}
}
return
}
if (typeof n2.type === 'string') {
if (!n1) mountElement(n2, container)
else patchElement(n1, n2, container)
} else if (typeof n2.type === 'object' || typeof n2.type === 'function') {
// component
if (!n1) mountComponent(n2, container)
else {
// simple: re-mount component (could be optimized)
mountComponent(n2, container)
}
} else if (Array.isArray(n2)) {
// root array of vnodes
n2.forEach(child => patch(null, child, container))
}
}
return { createApp: (rootComponent) => {
return {
mount(selector) {
const container = document.querySelector(selector)
const vnode = h(rootComponent)
patch(null, vnode, container)
}
}
}, patch }
}
/* ---------------------------
Expose runtime helpers
--------------------------- */
const { createApp, patch } = createRenderer()
const runtime = { h, createTextVNode }
/* ---------------------------
Demo app / usage
--------------------------- */
// Simple Counter component using template
const Counter = {
template: `
<div class="counter">
<h2>Count: {{ count }}</h2>
<div>
<button @click="inc"> + </button>
<button @click="dec"> - </button>
</div>
</div>
`,
setup() {
const state = reactive({ count: 0 })
function inc() { state.count++ }
function dec() { state.count-- }
// expose to template as returned object
return { ...state, inc, dec }
}
}
// App component with nested component and ref
const App = {
template: `
<div>
<h1>mini-vue demo</h1>
<div>{{ message }}</div>
<Counter></Counter>
</div>
`,
components: { Counter },
setup() {
const message = ref('Hello from mini-vue!')
return { message: message.value ? message.value : message } // simple
},
// when using components in template we support <Counter></Counter> by adding runtime type lookup:
render(ctx) {
// fallback simple render if compiler didn't wire components - but we used template so ok
return h('div', null, [
h('h1', null, 'mini-vue demo (fallback render)'),
h('div', null, ctx.message)
])
}
}
// Small hack: when compiler sees a tag that matches registered component name,
// we should resolve it to the component object. Our compileTemplate currently emits
// string tags only; to support <Counter> we mount the root component manually here.
function mountAppWithComponents(rootComponent, selector) {
const app = createApp(rootComponent)
// intercept mount to inject component resolution into Component.template compile phase
// For simplicity: patch compileTemplate to resolve child element tag names to components if present.
// We'll replace mount to pre-register components on global scope for the template compiler.
// Quick approach: before mounting, replace Counter tag occurrences in template with a placeholder element
// We'll do a very simple runtime: when encountering element tag with capitalized name, treat it as component.
// To do that, augment createRenderer.patch to treat vnode.type names starting with uppercase as component lookup.
// Easiest: monkey patch rootComponent.template: replace <Counter> with <div data-component="Counter"></div> and let mountComponent handle it.
// But due to time, we'll just mount a manual composed vnode:
const container = document.querySelector(selector)
// Render root: use compiled template if exists
// compile root template to render function and run it with ctx
const renderFactory = compileTemplate(rootComponent.template)
const renderFn = renderFactory({ h, createTextVNode })
const ctx = rootComponent.setup ? rootComponent.setup() : {}
// helper to resolve Counter tag: replace special <counter/> by calling component's render
// Simpler: create a wrapper vnode that contains the Counter component manually:
const rootVNode = h('div', null, [
h('h1', null, 'mini-vue demo'),
h('div', null, ctx.message),
h(Counter) // mount component vnode directly
])
// use internal patch to mount
patch(null, rootVNode, container)
}
mountAppWithComponents(App, '#app')
</script>
</body>
</html>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
# # 说明与学习要点
- reactive / ref / effect：这是一个完整但简化的实现，展示了
track/trigger/effect的工作流程（依赖收集与触发）。 - h + VNode + renderer：实现了最小的
h()、文本 vnode、元素 mount/patch、组件 mount（通过setup返回 state 或 render）。 - template compiler：使用浏览器的 DOM 解析器把模板解析成 AST，再生成一个简单的 render 函数。支持
插值和@click事件属性（映射为 props 上的 onClick），可以访问组件setup返回的上下文（_ctx）。 - 限制：这是教学实现，很多细节被极度简化或省略（比如 vnode key diff、详细 props diff、生命周期钩子、组件更新复用、scope/slots、复杂指令、复杂 JS 表达式安全处理、编译输出的缓存等）。但它涵盖了 Vue 核心设计的关键思想，便于你扩展、调试与深入源码。
上次更新: 2025/12/10, 08:07:53