implement frontend utility functions for classes and styles

src/renderer/services/utils.ts

@@ -0,0 +1,13 @@
+export function c(input: Array<string | boolean> | object): string {
+  const array = Array.isArray(input)
+    ? input.filter(el => typeof el === 'string')
+    : Object.keys(input).filter(key => !!input[key]);
+  return array.join(' ');
+}
+
+export function s(styles: object): string {
+  return Object.keys(styles)
+    .filter(key => !!styles[key])
+    .map(key => `${key}:${styles[key]}`)
+    .join(';');
+}