Update Readme

README.md

@@ -1,20 +1,38 @@
+
 # Modern Spreadsheet
 
-- <span>High performance spreadsheet based on CanvasAPI.</span>
+  
-- <span>TypeScript supported</span>
 
-<div>
+-  High performance spreadsheet based on CanvasAPI.
-<span>Basic usage</span>
+
+-  TypeScript supported
+
+  Basic usage
 
 ```js
-import { Spreadsheet } from 'modern_spreadsheet'
+import { Spreadsheet } from  'modern_spreadsheet'
-import 'modern_spreadsheet/style.css'   // <= this is required
 
-const target = document.getElementById('spreadsheet')
+import  'modern_spreadsheet/style.css'  // <= this is required
+
+const  target = document.getElementById('spreadsheet')
+
+const  sheet = new  Spreadsheet(target)
+//...
 
-const sheet = new Spreadsheet(target)
 ```
 
-<span>Load data</span>
+Save and load data
+```js
+function saveData() {
+	const serialized = sheet.serializeData()
+	localStorage.setItem('sheet_data', JSON.stringify(serialized))
+}
 
+function loadData() {
+	const data = localStorage.getItem('sheet_data')
+	const json = JSON.parse(data)
+	if(!json) return;
+	sheet.loadData(json)
+}
+```
 </div>