Rewrite composeClasses

Author: lttb

src/injectStyled.js

@@ -11,7 +11,7 @@ const injectStyled = (styled: StyledType) => (InnerComponent: ReactClass<any>) =
   const classes = [...classNames]
     .reduce((acc, name) => ({
       ...acc,
-      [name]: composeClasses(staticSheet.classes[name], dynamicSheet.classes[name]),
+      [name]: composeClasses([staticSheet.classes[name], dynamicSheet.classes[name]]),
     }), {})
 
   return (props: Object) => createElement(InnerComponent, {classes, ...props})

src/styled.js

@@ -69,11 +69,11 @@ const styled = ({tagName, elementStyle, mountSheets}: StyledArgs) => {
       const {children, className, ...attrs} = this.props
 
       const props = filterProps(attrs)
-      const tagClass = composeClasses(
+      const tagClass = composeClasses([
         this.staticSheet.classes[staticTagName],
         this.dynamicSheet.classes[this.dynamicTagName],
         className
-      )
+      ])
 
       return createElement(tagName, {...props, className: tagClass}, children)
     }

src/utils/composeClasses.js

@@ -1 +1,8 @@
-export default (...args: any) => args.filter(Boolean).join(' ')
+export default (classes: Array<?string | boolean>) => {
+  const filtered = []
+  for (let len = classes.length, index = 0; index < len; index++) {
+    if (classes[index]) filtered.push(classes[index])
+  }
+
+  return filtered.join(' ')
+}