JS Getter 与 Setter DAY71

Setter 与 Setter
Getter: 取得特定值的方法
Setter: 存值的方法

Getter

var wallet = {
    total: 100,
    set save(price){
        this.total = this.total + price / 2
    }
}
wallet.save = 300;
console.log(wallet.total); // 250

Getter + Setter

var wallet = {
    total: 100,
    set save(price){
        this.total = this.total + price / 2
    },
    get save(){
        return this.total / 2;
    }
}
wallet.save = 300;
console.log(wallet.save); // 125

另一种定义方式(Object.defineProperty)
但要注意
如果用 defineProperty 去定义getter , setter
则 enumerable , configurable 预设为false

var wallet = {
    total: 100,
}
Object.defineProperty(wallet,'save',{
    configurable: true,
    enumerable: true,
    set : function(price){
        this.total = this.total + price / 2;
    },
    get : function(){
        return this.total / 2;
    }
})
wallet.save = 300;
console.log(wallet);

这里在举一个例子

var a = [1,2,3];
Object.defineProperty(Array.prototype,'latest',{
    get: function(){
        return this[this.length - 1]
    }
})
console.log(a.latest);

那今天的介绍就到这里
若有任何问题 或 内容有误
都可以跟我说唷