获得时间（倒计时） - Html，Javascript，AngularJS

Basically, I'm trying to build a spaceship launch app that pulls data from say, a spreadsheet, and displays the time left for each spacecraft's launch. BTW, I did look at the (few) questions on Stack right now about getting time left, but they don't seem very comprehensive and I'm confused on how to implement them into my code.Basically, I'm trying to build a spaceship laun