React is a JavaScript library, and so it assumes you have a basic understanding of the JavaScript language. If you don't feel very confident, we recommend refreshing your JavaScript knowledge so you can follow along more easily.

React 是一个JavaScript库，所以我们假设你有对JavaScript语言有一个基本的了解。如果你感觉不是很有信心，我们建议更新JavaScript知识，那样能学的更简单。

We also use some of the ES6 syntax in the examples. We try to use it sparingly because it's still relatively new, but we encourage you to get familiar with arrow functions, classes, template literals, let, and const statements. You can use Babel REPL to check what ES6 code compiles to.

我们同样在事例中使用了ES6语法。我们会尽量谨慎使用它，毕竟ES6相对来说还是很新的。但是我们鼓励你熟悉箭头函数，类，模板字面量，let和const的语句。你可以使用Babel REPL检验ES6代码都编译成什么了。