javascript – 每个JSON数据记录添加对象

基于 JSON数据,如何在代码片段中添加新元素(这是我的意思是行星)到下面的恒星系统：

[{
           "rowid": 1,"Radius size": 3,"Distance": 110 pixels,},{
           "rowid": 2,"Size": 2.5,"Distance": 120 pixels,}]

每行ID是自己的行星,具有自己的尺寸和位置.距离当然是基于行星与太阳元件的距离,这是页面的中心.每个行星的距离需要处于不同的角度,否则它们将完全排列(不切实际).关于如何实现这一点的任何想法？

var ball = {};

function makeBall(spec) {
  // Create the element
  var circle = document.createElementNS("http://www.w3.org/2000/svg","circle");
  // Set its various attributes
  ["id","cx","cy","r","class"].forEach(function(attrName) {
    if (spec.element[attrName]) {
      circle.setAttribute(attrName,spec.element[attrName]);
    }
  });
  // Add it to the sun
  document.getElementById("Sun2").appendChild(circle);
  // Remember its animation settings in `ball`
  ball[spec.element.id] = spec.animation;
}

function addObject() {
  // Create a spec to use with makeBall from the fields
  var spec = {
    element: {
      id: document.getElementById("new-id").value,class: document.getElementById("new-class").value,r: parseFloat(document.getElementById("new-r").value)
    },animation: {
      speed: 2,spin: 30,side: 40
    }
  };
  // Some minimal validation
  if (!spec.element.id || !spec.element.r || !spec.animation.speed || !spec.animation.spin || isNaN(spec.animation.side)) {
    alert("Need all values to add a ball");
  } else if (ball[spec.element.id]) {
    alert("There is already a ball '" + spec.element.id + "'");
  } else {
    // Do it!
    makeBall(spec);
  }
}

function rotation(coorX,coorY,object) {
  object.side += (1.0 / object.speed);
  var ang = object.side * 2.0 * Math.PI / 180.0;
  var r = object.spin;

  return {
    x: Math.cos(ang) * r - Math.sin(ang) * r + coorX,y: Math.sin(ang) * r + Math.cos(ang) * r + coorY
  };
}

function rotationball(circle) {
  var x,y,x_black,y_black,e,newpos,black;

  // We always rotate around black
  black = document.getElementById("black");
  
  // Get this circle and update its position
  e = document.getElementById(circle);
  x_black = parseFloat(black.getAttribute("cx"));
  y_black = parseFloat(black.getAttribute("cy"));
  newpos = rotation(x_black,ball[circle]);

  e.setAttribute("cx",newpos.x);
  e.setAttribute("cy",newpos.y);
}

function animate() {
  Object.keys(ball).forEach(function(id) {
    rotationball(id);
  });
}

var animateInterval = setInterval(animate,1000 / 60);

.st0 {
  fill: yellow;
}

.st1 {
  fill: orange;
}

<div>Add ball:
  <label>
    ID: <input type="text" id="new-id" value="newball">
  </label>
  <label>
    R: <input type="text" id="new-r" value="10">
  </label>
  <label>
    Speed: <input type="text" id="new-speed" value="1.2">
  </label>
  <label>
    Spin: <input type="text" id="new-spin" value="80">
  </label>
  <label>
    Side: <input type="text" id="new-side" value="0.0">
  </label>
  <label>
    Class: <input type="text" id="new-class" value="st1">
  </label>
  <button type="button" onclick="addObject()">
    Make Ball
  </button>
</div>

<div class="spinning">
  <svg xmlns="http://www.w3.org/2000/svg" id="solly" viewBox="0 0 1000 600">
    <g id="Sun2">
      <circle id="black" class="st0" cx="500" cy="300.8" r="10" />
    </g>
  </svg>
</div>

以上是代码(不完全是我的),如果它有自己的ID,则添加新的球(行星).我只是想用JSON数据集来切换它.

编辑：
以下是两个记录的原始示例.您可以看到它提供了更多但冗余的属性.我从每个记录中真正需要的是大小(行星半径[木星半径]和距离(距离[pc])).距离将需要转换为像素,大小更加棘手.

[{
       "rowid": 1,"Host name": "TrES-3","Number of Planets in System": 1,"Planet Mass or M*sin(i)[Jupiter mass]": 1.91,"Planet Radius [Jupiter radii]": 1.336,"Planet Density [g": {
          "cm**3]": 0.994
       },"Distance [pc]": 228,"Effective Temperature [K]": 5650,"Date of Last Update": "5/14/2014"
    },{
       "rowid": 2,"Host name": "UZ For","Number of Planets in System": 2,"Planet Mass or M*sin(i)[Jupiter mass]": 6.3,"Planet Radius [Jupiter radii]": null,"Planet Density [g": {
          "cm**3]": null
       },"Distance [pc]": null,"Effective Temperature [K]": null,"Date of Last Update": "5/14/2014"
    }]

解决方法

其实很简单：

如果您阅读HTML,您会注意到点击“Make Ball”按钮将调用addObject().所以你去检查JS代码中的那个函数.
addObject()简单地将输入域中的值解析为一个名为spec的对象,然后调用makeBall(spec).

您需要做的是为每个JSON数据提供与makeBall函数完全相同的数据对象规范.

function addObjectsFromJson(json){
    // using try catch block because JSON.parse will throw an error if the json is malformed
    try{
        var array = JSON.parse(json);
        for(var i = 0; i < array.length; i++){
            var planet = array[i];
            // create a spec to use with makeBall from the json
            var spec = {
                element: {
                    id: planet.rowid,// you don't provide a style class in your json yet,using yellow as default
                    class: 'st0',// your json must have a standard property for radius,// currently you have "Radius size" (is wrong since
                    // properties cannot have spaces) and "Size"
                    r: planet["Planet Radius [Jupiter radii]"]
                },animation: {
                    speed: 2,side: planet["Distance [pc]"]
                }
            };
            makeBall(spec);
        }
    }catch(e){
        console.log('error: ' + e);
    }
}

我在makeBall()函数中看不到添加一个距离的属性.

通过jQuery处理JSON通过jQuery：

// assuming your local server runs on port 8080
$.getJSON('localhost:8080/path/to/your/file',function (json) {
    // since we use getJSON,it is already parsed and a javascript object
    // additional parsing inside the addObjectsFromJson function is not necassary
    // and would throw an error
    addObjectsFromJson(json);
});

function addObjectsFromJson(json) {
    for (var i = 0; i < json.length; i++) {
        var planet = json[i];
        // create a spec to use with makeBall from the json
        var spec = {
            element: {
                id: planet.rowid,using yellow as default
                class: 'st0',// currently you have "Radius size" (is wrong since properties cannot have spaces) and "Size"
                    r: planet["Planet Radius [Jupiter radii]"]
                },side: planet["Distance [pc]"]
        };
        makeBall(spec);
    }
}