字符串可以直接遍歷啦

for(let codepoint of 'foo'){
    console.log(codepoint); // f,o,o
}

includes(), startsWidth(), endsWidth()

const s='hello world';
s.startWidth('hello') // true
s.endsWidth('d') // true
s.includes('o')  // true
s.includes('1')  // false

repeat

'x'.repeat(3) // xxx

模板字符串

let name="bob", time ="today";
console.log(`hello ${name}, how are you${time}`)