pop  从末尾删除
         shift 从前面删除
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title></head><body><script>// pop 从末尾删除// shift 从前面删除var arr = [1,2,3,4];arr.pop();//[1,2,3]arr.shift();//[2,3]console.log(arr)</script></body></html>

