javascript - Access child Object in js - Stack Overflow

admin管理员组

文章数量:1355107

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();

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);

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

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

Can Someone please help me?

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();

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);

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

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

Can Someone please help me?

• javascript
• hierarchy

Share Improve this question Follow edited Nov 21, 2017 at 12:36 TessavWalstijn 1,73622 gold badges2222 silver badges3737 bronze badges asked Nov 21, 2017 at 12:22 dieKoderindieKoderin 1,58233 gold badges1919 silver badges4343 bronze badges 1

• 4 solarySystem.children[0].radius – martskins Commented Nov 21, 2017 at 12:26

Add a ment  | 

2 Answers 2

Sorted by: Reset to default 3

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 is an array, so use 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);

First of all your .children is an array. so call .children[i].radius.
Second:

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

You call here once the draw function for the full children array. So you need to implement a for loop.

For this there are a lot options this is my approach:

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);

本文标签： javascriptAccess child Object in jsStack Overflow