feat(utils): 新增 signal

src/utils/index.ts

@@ -70,6 +70,7 @@ export * from './run'
 export * from './sampleBy'
 export * from './sampleIndex'
 export * from './selectDom'
+export * from './signal'
 export * from './swap'
 export * from './traverse'
 export * from './TreeData'

src/utils/signal.test.ts

@@ -0,0 +1,37 @@
+import { signal } from './signal'
+import { wait } from './wait'
+
+describe('signal', () => {
+  test('resolve', async () => {
+    let x = 0
+    const s = signal<number>()
+    s.then(_x => (x = _x))
+    expect(x).toBe(0)
+    s.resolve(2)
+    await wait(0)
+    expect(x).toBe(2)
+
+    // 只会触发一次 Promise
+    s.resolve(22)
+    await wait(0)
+    expect(x).toBe(2)
+  })
+
+  test('reject', async () => {
+    const x = 0
+    let err = ''
+    const s = signal<number>()
+    s.catch(_err => (err = _err))
+    expect(x).toBe(0)
+    expect(err).toBe('')
+    s.reject('err')
+    await wait(0)
+    expect(x).toBe(0)
+    expect(err).toBe('err')
+
+    // 只会触发一次 Promise
+    s.reject('err2')
+    await wait(0)
+    expect(err).toBe('err')
+  })
+})

src/utils/signal.ts

@@ -0,0 +1,46 @@
+/**
+ * 信号。
+ */
+export function signal<T>(): Promise<T> & {
+  resolve: (value: T) => void
+  reject: (err: any) => void
+} {
+  let _resolve: any
+  let _reject: any
+
+  let resolved = false
+  let resolvedValue: any
+  const resolve = (value: any) => {
+    if (!resolved) {
+      resolved = true
+      resolvedValue = value
+      _resolve?.(value)
+    }
+  }
+
+  let rejected = false
+  let rejectedValue: any
+  const reject = (value: any) => {
+    if (!rejected) {
+      rejected = true
+      rejectedValue = value
+      _reject?.(value)
+    }
+  }
+
+  const s: any = new Promise(($resolve, $reject) => {
+    if (resolved) {
+      $resolve(resolvedValue)
+    } else if (rejected) {
+      $reject(rejectedValue)
+    } else {
+      _resolve = $resolve
+      _reject = $reject
+    }
+  })
+
+  s.resolve = resolve
+  s.reject = reject
+
+  return s
+}