在js中访问子对象

Question

function Luminary(radius, orbitRadius, speed, children) {
    this.radius = radius;
    this.orbitRadius = orbitRadius;
    this.speed = speed;
    this.children = children;
}

function initSolarSystem() {
    var moon = new Luminary(0.02, 0.2, 0.0015, []);
    var earth = new Luminary(0.1, 0.7, 0.001, [moon]);
    var sun = new Luminary(0.3, 0.0, 0.0, [earth]);
    return sun;
}

var solarSystem = initSolarSystem();

我在 JS 中有上面的代码。我如何使用 solarSystem 对象访问地球的半径？以下returns未定义 alert(solarSystem.children.radius);

递归函数中应该如何调用children:

function draw(obj) {
    // draw Current Object 
    if (obj.children != undefined) {
      draw(obj.children);
    }
}

draw(solarSystem);

有人可以帮帮我吗？

Answer 1

I have the code above in JS. How can I access for example the radius of earth using the solarSystem object? The following returns Undefined alert(solarSystem.children.radius);

solarSystem.children是数组，所以用solarSystem.children[0].radius

How should I call children in a recursive function as follows.

function draw(obj) 
{
  // draw Current Object

  if (obj.children != undefined) 
  {
    obj.children.forEach( s => draw(s) ); //invoke draw in a loop
    //draw(obj.children[0]); //use 
  }
}

draw(solarSystem);

Answer 2

首先你的 .children 是一个数组。所以打电话给 .children[i].radius.
第二个：

if (obj.children != undefined) {
  draw(obj.children);
}

您在这里调用一次完整 children 数组的绘制函数。所以你需要实现一个for循环。

对此有很多选择，这是我的方法：

function Luminary(name, radius, orbitRadius, speed, children = []) {
    this.name = name;
    this.radius = radius;
    this.orbitRadius = orbitRadius;
    this.speed = speed;
    this.children = children;
}

function initSolarSystem() {
    var moon = new Luminary("moon", 0.02, 0.2, 0.0015);
    var earth = new Luminary("earth", 0.1, 0.7, 0.001, [moon]);
    var sun = new Luminary("sun", 0.3, 0.0, 0.0, [earth]);
    return sun;
}

var solarSystem = initSolarSystem();

function draw(obj) {
    // Draw current object.
    for (let key in obj.children)
      if (obj.children.hasOwnProperty(key)) {
        //if (typeof(obj.children) == "array") {
         console.log(obj.children[key].radius);
          draw(obj.children[key]);
        }
}

draw(solarSystem);

在js中访问子对象

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