扣筆記 CodeNotes by kaiyuncheng

Subclassing a built-in 的兩個障礙:

Obstacle 1 帶有內部特性的實體

function Super(x, y){
 this.x = x;
 this.y = y;
}

function Sub(x, y ,z){
 Super.call(this, x, y);
 this.z = z;
}

內建建構器會忽略傳入傳入作為this的子實體