我正在学习JS,我创建了一个这样的类Entity
:
class Entity {
constructor(x=0, y=0, dx=0, dy=0, width=50, height=50, solid=false,
color="black", name="entity", id=Math.random()) {
this.x = x;
this.y = y;
this.dx = dx;
this.dy = dy;
this.width = width;
this.height = height;
this.solid = solid;
this.color = color;
this.name = name;
this.id = id;
entityList[id] = this;
}
UpdatePosition() {
this.x += this.dx;
this.y += this.dy;
}
Draw() {
ctx.save();
ctx.fillStyle = this.color;
ctx.fillRect(this.x, this.y, this.width, this.height);
ctx.restore();
}
BorderCollision() {
if (this.solid == true) {
if (this.x <= 0) {
this.dx = -this.dx;
}
if (this.x + this.width >= canvas.width) {
this.dx = -this.dx;
}
if (this.y <= 0) {
this.dy = -this.dy;
}
if (this.y + this.height >= canvas.height) {
this.dy = -this.dy;
}
}
}
EntityUpdate() {
this.UpdatePosition();
this.Draw();
this.BorderCollision();
}
}
现在,我想在一个名为
Player
的新类中扩展这个类,该类具有一个新成员:canMove
但是当我写
constructor(canMove) {this.canMove = canMove; +}
时我不知道如何做一个新的构造函数,我得到一个错误:(谢谢 ;) !
最佳答案
如果要扩展类并定义构造函数,则要使用super()
,则需要调用this
:
class Player extends Entity {
constructor(canMove) {
// super.constructor(); - NO
super(); // Yes
this.canMove = canMove;
}
}
您可能还希望将一些参数传递给
super
,并且由于您几乎不想复制整个参数列表,因此您可能希望使用options object而不是10个单独的参数。关于javascript - JS扩展构造函数类,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/39073400/