数组的方法---------------------------------------
1、数组头部添加删除元素
unshift() 添加
shift() 删除
2、数组尾部添加删除元素
push() 添加
pop() 删除
3、数组的拷贝
slice() 可以有一个或者两个参数
2 3 4 5 6 7 8 9 | var numbers = [1,2,3,4,5]; console.log(numbers.slice(2)); //[3,4,5] console.log(numbers.slice(2,undefined)); //[3,4,5] console.log(numbers.slice(2,3)); //[3] console.log(numbers.slice(2,1)); //[] console.log(numbers.slice(-3)); //-3+5=2 -> [3,4,5] console.log(numbers.slice(-8)); //max(5 + -8,0)=0 -> [1,2,3,4,5] console.log(numbers.slice(0,-3)); //-3+5=2 -> [1,2] console.log(numbers.slice(-2,-1)); //-2+5=3;-1+5=4; -> [4] |