Merge branch 'feat-support-start'

src/useInterval.ts

@@ -5,18 +5,24 @@ export function useInterval(fn: Function, delay: number, immediate = false) {
   const clear = () => {
     if (interval) {
       clearInterval(interval)
+      interval = null
+    }
+  }
+  const start = () => {
+    if (!interval) {
+      interval = setInterval(fn, delay)
     }
   }
   useLifecycles(
     () => {
       if (fn) {
         immediate && fn()
-        interval = setInterval(fn, delay)
+        start()
       }
     },
     () => {
       clear()
     }
   )
-  return clear
+  return [clear, start]
 }

tests/useInterval.test.ts

@@ -35,11 +35,29 @@ test('should clearInterval when unmounted', () => {
 })
 
 test('interval should be cleared after invoking clear', () => {
-  let clear: () => void | undefined
+  let clear: () => void
   invokeHook(() => {
-    clear = useInterval(callback!, 500)
+    [clear] = useInterval(callback!, 500)
   })
   clear!()
   expect(clearInterval).toHaveBeenCalledTimes(1)
   expect(clearInterval).toHaveBeenCalledWith(expect.any(Number))
 })
+
+test('interval will be start after invoking start', () => {
+  let clear: () => void
+  let start: () => void
+  invokeHook(() => {
+    const res = useInterval(callback!, 500)
+    clear = res[0]
+    start = res[1]
+  })
+  clear!()
+  expect(clearInterval).toHaveBeenCalledTimes(1)
+  expect(clearInterval).toHaveBeenCalledWith(expect.any(Number))
+  start()
+  expect(setInterval).toHaveBeenCalled()
+  expect(setInterval).toHaveBeenCalledWith(expect.any(Function), 500)
+  jest.advanceTimersByTime(500)
+  expect(callback).toHaveBeenCalled()
+})