如何根据以下JSON数据向代码片段中的以下恒星系统添加新元素（我的意思是行星）？
[{
"rowid": 1,
"Radius size": 3 ,
"Distance": 110 pixels,
},
{
"rowid": 2,
"Size": 2.5,
"Distance": 120 pixels,
}]
每一行ID都是它自己的行星，有自己的大小和位置。距离当然取决于行星距太阳元素的距离，太阳元素是页面的中心。每个行星的距离需要处于不同的角度，否则它们都会完美排列（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, y_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>
编辑： 以下是两个记录的原始示例。正如您所看到的，它提供了更多但多余的属性。我真正需要的每个记录的大小（行星半径[木星半径]和距离（距离[pc]）。距离需要转换为像素，大小比较棘手。
[{
"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"
}]
答案 0 :(得分：1)
实际上非常简单：
如果您阅读HTML，您会注意到单击“Make Ball”按钮将调用addObject（）。所以你去JS代码中检查一下这个函数。 addObject（）只是将输入字段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makeBall函数的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,
spin: 30,
side: planet["Distance [pc]"]
}
};
makeBall(spec);
}
}catch(e){
console.log('error: ' + e);
}
}
虽然我没有在makeBall（）函数中看到添加距离的属性。
使用jQuery通过ajax处理JSON：
// 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,
// 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,
spin: 30,
side: planet["Distance [pc]"]
};
makeBall(spec);
}
}