11.反射

console.log(Math.floor.apply(null, [3.72]))
console.log(Reflect.apply(Math.floor, null, [4.72]))
// Math.ceil
let price = 91.5
if (price > 100) {
  price = Math.floor.apply(null, [price])
} else {
  price = Math.ceil.apply(null, [price])
}
console.log(Reflect.apply(price > 100 ?
Math.floor : Math.ceil, null, [price]))
// object
let d = new Date()
console.log(d.getTime())

let d = Reflect.construct(Date, [])
console.log(d.getTime(), d instanceof Date)

const student = {}
const r = Reflect.defineProperty(student, 'name',
{ value: 'Mike2' })
console.log(student, r)
const obj = { x: 1, y: 2 }
Reflect.deleteProperty(obj, 'x')
console.log(obj)
console.log(Reflect.get(obj, 'x'))
console.log(Reflect.get([3, 4], 1))

console.log(Object.getOwnPropertyDescriptor(obj, 'y'))

let d = new Date()
console.log(Reflect.getPrototypeOf(d))
const obj = { x: 1, y: 2 }
console.log(Reflect.has(obj, 'y'))
obj.z = 3
Object.freeze(obj)
obj.z = 3
console.log(Reflect.isExtensible(obj))
console.log(obj)
console.log(Reflect.ownKeys(obj))
console.log(Reflect.ownKeys([1, 2]))
// Symbol
Reflect.preventExtensions(obj)
console.log(Reflect.isExtensible(obj))
Reflect.set(obj, 'z', 4)
console.log(obj)
const arr = ['duck', 'duck', 'duck']
// Reflect.set(arr, 2, 'goose')
console.log(arr)
console.log(Reflect.getPrototypeOf(arr))
Reflect.setPrototypeOf(arr, String.prototype)
// arr.sort()
console.log(Reflect.getPrototypeOf(arr))

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