react react-component props states componentdidmount a-stateless-functional-component a-stateless-component a-stateful-component pass-an-array-as-props use-default-props access-props use-state-to-toggle-an-element render-with-an-if-else-condition ternary-expression writing-a-simple-counter create-a-controlled-input pass-state-as-props pass-a-callback-as-props use-the-lifecycle-method componentwillmount