异步函数在循环中不会产生立即结果

I am new to nodejs and what I have done is I have connected LCD Panel and 4x4 Membrane matrix keypad to Raspberry Pi and I have programmed them using Node.js. What I want to achieve is whenever a key is pressed it should be displayed immediately on the LCD panel and when I press # it should stop taking input.I am new to nodejs and what I have done is I ha