vueuse · antfu · Jul 24, 2022 · Jun 10, 2022 · Jun 17, 2022 · Jun 17, 2022
diff --git a/packages/core/index.ts b/packages/core/index.ts
@@ -102,6 +102,7 @@ export * from './useStyleTag'
 export * from './useSupported'
 export * from './useSwipe'
 export * from './useTemplateRefsList'
+export * from './useTextDirection'
 export * from './useTextSelection'
 export * from './useTextareaAutosize'
 export * from './useThrottledRefHistory'

diff --git a/packages/core/useTextDirection/demo.vue b/packages/core/useTextDirection/demo.vue
@@ -0,0 +1,41 @@
+<script setup lang="ts">
+import { computed, onUnmounted } from 'vue'
+
+import { useTextDirection } from './index'
+
+const dir = useTextDirection({
+  selector: '#_useTextDirectionDemo',
+})
+const text = computed(() =>
+  dir.value === 'ltr'
+    ? 'This paragraph is in English and correctly goes left to right.'
+    : 'This paragraph is in English but incorrectly goes right to left.',
+)
+
+const handleOnClick = () => {
+  dir.value = dir.value === 'rtl' ? 'ltr' : 'rtl'
+}
+</script>
+
+<template>
+  <div id="_useTextDirectionDemo">
+    <p>
+      {{ text }}
+    </p>
+    <hr>
+    <button @click="handleOnClick">
+      <span class="ml-2">{{ dir.toUpperCase() }}</span>
+    </button>
+    <span class="p-4 opacity-50">Click to change the direaction</span>
+  </div>
+</template>
+
+<style scoped>
+#_useTextDirectionDemo[dir='rtl']
+p {
+  color: red;
+}
+button {
+  margin-right: 0.5em;
+}
+</style>
diff --git a/packages/core/useTextDirection/index.md b/packages/core/useTextDirection/index.md
@@ -0,0 +1,35 @@
+---
+category: Browser
+---
+
+# useTextDirection
+
+Reactive [dir](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/dir) of the element's text.
+
+## Usage
+
+```ts
+import { useTextDirection } from '@vueuse/core'
+
+const dir = useTextDirection() // Ref<'ltr' | 'rtl' | 'auto'>
+```
+
+By default, it returns `rlt` direction when dir `rtl` is applied to the `html` tag, for example:
+
+```html
+<!--ltr-->
+<html> ... </html>
+
+<!--rtl-->
+<html dir="rtl"> ... </html>
+```
+
+## Options
+
+```ts
+import { useTextDirection } from '@vueuse/core'
+
+const mode = useTextDirection({
+  selector: 'body'
+}) // Ref<'ltr' | 'rtl' | 'auto'>
+```
diff --git a/packages/core/useTextDirection/index.ts b/packages/core/useTextDirection/index.ts
@@ -0,0 +1,75 @@
+import { tryOnMounted } from '@vueuse/shared'
+import { computed, ref } from 'vue-demi'
+
+import type { MaybeElement } from '../unrefElement'
+import { useMutationObserver } from '../useMutationObserver'
+import type { ConfigurableDocument } from '../_configurable'
+import { defaultDocument } from '../_configurable'
+
+export type UseTextDirectionValue = 'ltr' | 'rtl' | 'auto'
+
+export interface UseTextDirectionOptions extends ConfigurableDocument {
+  /**
+   * CSS Selector for the target element applying to
+   *
+   * @default 'html'
+   */
+  selector?: string
+  /**
+   * Observe `document.querySelector(selector)` changes using MutationObserve
+   *
+   * @default false
+   */
+  observe?: boolean
+  /**
+   * Initial value
+   *
+   * @default 'ltr'
+   */
+  initialValue?: UseTextDirectionValue
+}
+
+/**
+ * Reactive dir of the element's text.
+ *
+ * @see https://vueuse.org/useTextDirection
+ */
+export function useTextDirection(options: UseTextDirectionOptions = {}) {
+  const {
+    document = defaultDocument,
+    selector = 'html',
+    observe = false,
+    initialValue = 'ltr',
+  } = options
+
+  function getValue() {
+    return document?.querySelector(selector)?.getAttribute('dir') as UseTextDirectionValue ?? initialValue
+  }
+
+  const dir = ref<UseTextDirectionValue>(getValue())
+
+  tryOnMounted(() => dir.value = getValue())
+
+  if (observe && document) {
+    useMutationObserver(
+      document.querySelector(selector) as MaybeElement,
+      () => dir.value = getValue(),
+      { attributes: true },
+    )
+  }
+
+  return computed<UseTextDirectionValue>({
+    get() {
+      return dir.value
+    },
+    set(v) {
+      dir.value = v
+      if (!document)
+        return
+      if (dir.value)
+        document.querySelector(selector)?.setAttribute('dir', dir.value)
+      else
+        document.querySelector(selector)?.removeAttribute('dir')
+    },
+  })
+}