展开运算符

<script type="text/javascript" >

            let arr1 = [1,3,5,7,9]

            let arr2 = [2,4,6,8,10]

            console.log(...arr1); //展开一个数组

            let arr3 = [...arr1,...arr2]//连接数组

            console.log(arr3);

            

            //在函数中使用

            function sum(...numbers){

                return numbers.reduce((preValue,currentValue)=>{

                    return preValue + currentValue

                })

            }

            console.log(sum(1,2,3,4));

            //构造字面量对象时使用展开语法

            let person = {name:'tom',age:18}

            let person2 = {...person}

            //console.log(...person); //报错，展开运算符不能展开对象

            person.name = 'jerry'

            console.log(person2);

            console.log(person);

            //合并

            let person3 = {...person,name:'jack',address:"地球"}

            console.log(person3);

            

        </script>