JS Proxy对象使用的两个案例：校验器和属性私有化

校验器

const target = {_id: '1024',name: 'vuejs',
}// 校验器
const validators = {name(val) {return Object.prototype.toString.call(val) === 'string';},_id(val) {return Object.prototype.toString.call(val) === 'number';}
}const createValidator = (target, validators) => {return new Proxy(target, {_validator: validators,set(target, propKey, value, proxy) {let validator = this._validator[propKey](value)if(validator) {return Reflect.set(target, propKey, value, proxy)} else {throw Error(`无法设置属性为${propKey}的值为${value}，类型不匹配`)}}})
}const targetProxy = createValidator(target, validators)// targetProxy.name = 1234 // Error: 无法设置属性为name的值为1234，类型不匹配
// targetProxy._id = '1234' // Error: 无法设置属性为_id的值为1234，类型不匹配

属性私有化

const target = {_id: '1024',name: 'vuejs',
}const createProxy = (target) => {return new Proxy(target, {get: function(target, propKey, proxy) {if(propKey[0] === '_') {throw Error(`${propKey} is privated`)}return Reflect.get(target, propKey, proxy)},set: function(target, propKey, value, proxy) {if(propKey[0] === '_') {throw Error(`${propKey} is privated, can not set ${value}`)}return Reflect.set(target, propKey, value, proxy)}})
}const targetProxy = createProxy(target)// targetProxy._id = 123 // Error: _id is privated, can not set 123
// console.log(targetProxy._id) // Error: _id is privated