chore: add vant-icons package

packages/vant-icons/build/export.js

@@ -0,0 +1,18 @@
+const fs = require('fs-extra');
+const path = require('path');
+const shell = require('shelljs');
+
+const svgDir = path.join(__dirname, '../assets/svg');
+const sketch = path.join(__dirname, '../assets/icons.sketch');
+const SKETCH_TOOL_DIR = '/Applications/Sketch.app/Contents/Resources/sketchtool/bin/sketchtool';
+
+fs.removeSync(svgDir);
+
+// extract svg from sketch
+// should install sketchtool first
+// install guide: https://developer.sketchapp.com/guides/sketchtool/
+shell.exec(
+  `${SKETCH_TOOL_DIR} export slices --formats=svg --overwriting=YES --save-for-web=YES --output=${svgDir} ${sketch}`
+);
+
+shell.exec('svgo ./assets/svg/*.svg');