1.判断是不是数组? const arr = [1,2,3,4] arr instanceof Array //true Object.prototype.toString.call(arr) === ‘[object Array]’; Array.isArray(arr) arr.constructor === Array arr.__ proto__ === Array.prototype 2.Flex:1代表什么? flex: 1 === flex: 1 1 0%; flex-grown flex-shr...