1.使用?`let/const`，而非?`var`?來聲明變量。 2.使用模板運算符，不必用++來嵌套連接字符串了。需要用?反引號 和字符串插值?`${}` ``` const first = 'Adrian'; const last = 'Mejia'; console.log(`Your name is ${first} ${last}.`); ``` 3.解構賦值 ``` const array = [1, 2, 3, 4]; const [first, ,third] = array; console.log(first, third); // 1 3 ``` 4.類和對象 ``` class Animal { constructor(name) { this.name = name; } speak() { console.log(this.name + ' makes a noise.'); } } const animal = new Animal('animal'); animal.speak(); // animal makes a noise. ``` 5.Promise:用?promise 替代回調地獄 ``` function printAfterTimeout(string, timeout){ return new Promise((resolve, reject) => { setTimeout(function(){ resolve(string); }, timeout); }); } printAfterTimeout('Hello ', 2e3).then((result) => { console.log(result); return printAfterTimeout(result + 'Reader', 2e3); }).then((result) => { console.log(result); }); ``` 6.箭頭函數