Javascript)コンストラクタ

const park = {
    first : 100,
    second : 20,
    count : 2,
    grade : function(){
        average = (this.first + this.second) / this.count
        return Math.floor(average)
    }
},
      
const kim = {
    first : 100,
    second : 50,
    count : 2,
    grade : function(){
        average = (this.first + this.second) / this.count
        return Math.floor(average)
    }
}

この点は、コンストラクション関数を使用して解決できます。

function oop(name, first, second, count){
    this.name = name
    this.first = first
    this.second = second
    this.count = count
    this.grade = function(){
        return Math.floor((this.first + this.second) / this.count)
    }
}

const park = new opp()
const kim = new opp()