Setter 與 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

另一種定義方式(Object.defineProperty)
但要注意
如果用 defineProperty 去定義getter , setter
則 enumerable , configurable 預設為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);

這裡在舉一個例子

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

那今天的介紹就到這裡
若有任何問題 或 內容有誤
都可以跟我說唷