From 24ed905715392ec715f4cb8c21b0f49d2c3cd5f0 Mon Sep 17 00:00:00 2001
From: pengzhanbo <volodymyr@foxmail.com>
Date: Mon, 30 Oct 2023 00:38:55 +0800
Subject: [PATCH] feat: add `useInViewport` hooks

---
 src/useInViewport/index.ts | 95 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 src/useInViewport/index.ts

diff --git a/src/useInViewport/index.ts b/src/useInViewport/index.ts
new file mode 100644
index 0000000..36120a0
--- /dev/null
+++ b/src/useInViewport/index.ts
@@ -0,0 +1,95 @@
+import 'intersection-observer'
+import { createSignal, onCleanup, onMount } from 'solid-js'
+import { getTargetElement } from '../utils/domTarget'
+import type { BasicTarget } from '../utils/domTarget'
+
+type CallbackType = (entry: IntersectionObserverEntry) => void
+
+export interface Options {
+  /**
+   * Margin around the root
+   *
+   * 根(root)元素的外边距
+   */
+  rootMargin?: string
+  /**
+   * Either a single number or an array of numbers which indicate at what percentage
+   * of the target's visibility the ratio should be executed
+   *
+   * 可以是单一的 number 也可以是 number 数组，
+   * target 元素和 root 元素相交程度达到该值的时候 ratio 会被更新
+   */
+  threshold?: number | number[]
+  /**
+   * The element that is used as the viewport for checking visibility of the target.
+   * Must be the ancestor of the target.
+   * Defaults to the browser viewport if not specified or if null.
+   *
+   * 指定根(root)元素，用于检查目标的可见性。必须是目标元素的父级元素，
+   * 如果未指定或者为 null，则默认为浏览器视窗
+   */
+  root?: BasicTarget<Element>
+  /**
+   * A callback function that [IntersectionObserver](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver)
+   *
+   * [IntersectionObserver](https://developer.mozilla.org/zh-CN/docs/Web/API/IntersectionObserver) 的回调函数
+   */
+  callback?: CallbackType
+}
+
+/**
+ * Observe whether the element is in the visible area of the viewport.
+ *
+ * 监听元素是否在可视区域内的钩子。
+ *
+ * @example
+ * ```ts
+ * const [inViewport, ratio] = useInViewport(() => element)
+ * ```
+ */
+export default function useInViewport(
+  target: BasicTarget | BasicTarget[],
+  options?: Options,
+) {
+  const { callback, ...option } = options || {}
+
+  // in viewport state
+  const [state, setState] = createSignal<boolean>()
+  // ratio state
+  const [ratio, setRatio] = createSignal<number>()
+
+  onMount(() => {
+    const targets = Array.isArray(target) ? target : [target]
+    const els = targets
+      .map((element) => getTargetElement(element))
+      .filter(Boolean)
+
+    if (!els.length) {
+      return
+    }
+    const observer = new IntersectionObserver(
+      (entries) => {
+        for (const entry of entries) {
+          setRatio(entry.intersectionRatio)
+          setState(entry.isIntersecting)
+          callback?.(entry)
+        }
+      },
+      {
+        ...option,
+        root: getTargetElement(options?.root),
+      },
+    )
+    els.forEach((el) => {
+      if (el) {
+        observer.observe(el)
+      }
+    })
+
+    onCleanup(() => {
+      observer.disconnect()
+    })
+  })
+
+  return [state, ratio] as const
+}