Content Analysis: This is an interesting problem from

Photo Gallery

BFE.dev#130. create LazyMan()  | JSer - Front End Interview questions
BFE.dev#113. Virtual DOM I | JSer - Front-End Interview questions
BFE.dev#143. Virtual DOM IV - JSX 1 (with & without RegExp) | JSer - Front-End Interview questions
BFE.dev #88 support negative Array index in JavaScript  | JSer - Front End Interview questions
bigfrontend.dev | 16. create an Event Emitter