feat(core): add utils (#427)

Author: ader-h

src/index.js

@@ -15,6 +15,7 @@ export { default as core } from './core';
 export { default as Theme } from './theme';
 export { default as Dragger } from './feature/drag';
 export { default as Card } from './feature/card';
+export { default as util } from './util';
 export { default as BarChart } from './components/BarChart';
 export { default as PieChart } from './components/PieChart';
 export { default as LineChart } from './components/LineChart';

src/util.js

@@ -0,0 +1,13 @@
+import * as echarts from 'echarts';
+import getTooltipContentHtmlStr from "./option/config/tooltip/formatter";
+
+const util = {
+  tooltip: {
+    formatter: getTooltipContentHtmlStr
+  },
+  echarts,
+  format: {
+    truncateText: echarts.format.truncateText
+  }
+}
+export default util