新增判断页面状态hooks

src/hooks/usePageStatus.ts

+import { history } from 'umi'
+import { useState } from 'react'
+
+export enum PageStatus {
+  ADD,
+  EDIT,
+  PREVIEW
+}
+
+export const usePageStatus = () => {
+  const { preview, id = '' } = history.location.query
+  // 默认预览状态
+  let pageStatus = PageStatus.PREVIEW
+  if (preview === '1') {
+    pageStatus = PageStatus.PREVIEW
+  } else {
+    if (id) {
+      pageStatus = PageStatus.EDIT
+    } else {
+      pageStatus = PageStatus.ADD
+    }
+  }
+
+  return {
+    pageStatus,
+    id,
+    preview
+  }
+}
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