Question

我正在尝试创建一个新对象，但是其中一个属性尚未初始化。 console.log(this.hitboxlen)输出undefined。我之前在hitbox属性中遇到了相同的问题，并通过在构造函数之外分配它来解决了该问题。

这是代码的主体

import Position from "./position";
import Character from "./character";

var canvas = document.getElementById("gcanvas");
var context = canvas.getContext("2d");

var char = new Character(10, null, 2);
var hb = [new Position(5, 5), new Position(10, 10)];

char.hitbox = hb;
console.log(char);

function update() {
  context.fillStyle = 'red';
  context.fillRect(char.hitbox[0].xx, char.hitbox[0].yy, 30, 30);
  requestAnimationFrame(update);
}

document.addEventListener('keydown', event => {
  if (event.keyCode === 37) {
    char.move("left");
  }
  else if (event.keyCode === 39) {
    char.move("right");
  }

});

update();

这是角色类

import Position from "./position";

class Character {
  constructor(health, hitboxlen) {
    this.hp = health;
    this.hitbox = [];
    this.hitbox = hitboxlen;
  }

  //passed string of either "left" or "right"

  move(direction) {
    var change = 5;
    console.log(this.hitboxlen);
    if (direction == "left") {
      change = -5;
    }
    for (var i = 0; i < 2; i++) {
      this.hitbox[i].xx = this.hitbox[i].xx + change;
    }

  }
}

export default Character;

Answer 1

您正在为this.hitbox分配hitboxlen。错误是在构造函数中 this.hitboxlen = hitboxlen

Javascript类属性被初始化为未定义

1 个答案: