const arr=[{'name':'sjp','sex':'女'},{'name':'jfq','sex':'女'}];for(const person of arr){console.log(person)}; {name: 'sjp', sex: '女'} {name: 'jfq', sex: '女'} undefined const arr=[{'name':'sjp','sex':'女'},{'name':'jfq','sex':'女'}];for(const person in arr){console.log(person)}; 0 1 const obj={'name':'sjp','sex':'女'};for (const property in obj){console.log(property)}; VM299:1 name VM299:1 sex for ... of ...通常用于对数组的操作。返回数组元素 for ... in ...通常用于对对象的操作。返回对象的属性名。若操作对象，会返回index
map,filter都不会改变原数组
