使用SVG基本操作API的實例講解

var SVG_NS = "http://www.w3.org/2000/svg";
var XLINK_NS = http://www.w3.org/1999/xlink;

document.createElementNS(SVG_NS,tagName);

element.appendChild(childElement)

element.setAttribute(name,value);
element.getAttribute(name);

element.setAttributeNS(XLINK_NS,'xlink:href',value);

function createTag(tag,objAttr){
 var oTag = document.createElementNS('http://www.w3.org/2000/svg',tag);
 for(var attr in objAttr){
 if(attr == 'xlink:href'){
 oTag.setAttributeNS("http://www.w3.org/1999/xlink",attr,objAttr[attr]);
 }else{
 oTag.setAttribute(attr,objAttr[attr]);
 } 
 } 
 return oTag;
}

<script>
function createTag(tag,objAttr){
 var oTag = document.createElementNS('http://www.w3.org/2000/svg',tag);
 for(var attr in objAttr){
 if(attr == 'xlink:href'){
 oTag.setAttributeNS("http://www.w3.org/1999/xlink",attr,objAttr[attr]);
 }else{
 oTag.setAttribute(attr,objAttr[attr]);
 } 
 } 
 return oTag;
} 
var oSvg = createTag('svg',{'version':'1.1','xmls':'http://www.w3.org/2000/svg',height:'70'});
var oCircle = createTag('circle',{'cx':'25','cy':'25','r':20,'fill':'pink'});
oSvg.appendChild(oCircle);
document.body.appendChild(oSvg);
</script>

<style>
#box{
 height: 300px;
 width: 300px;
 background: hsl(20,40%,90%);
 background-image:linear-gradient(90deg,#fb3 11px,transparent 0),
 linear-gradient(90deg,#ab4 23px,transparent 0),
 linear-gradient(90deg,#655 41px,transparent 0);
 background-size: 41px 100%,61px 100%,83px 100%; 
} 
</style>
<div id="box"></div>
<script>
var oSvg = createTag('svg',{'version':'1.1','xmls':'http://www.w3.org/2000/svg',height:'100%',width:'100%'});
var oBox = document.getElementById('box');
var W = parseInt(getComputedStyle(oBox).width);
var H = parseInt(getComputedStyle(oBox).height);
var appearance = {
 'dis':H/3,
 'r0':H/8,'r':H/10,
 'x0':W/2,'y0':H/2,
 'fontSize':H/20,
 'bg0':'hsla(0,0%,100%,.6)','bg':'hsla(0,0%,100%,.3)',
 'color0':'hsl(210,13%,30%)','color':'hsl(210,13%,30%)',
 'borderColor0':'rgba(0,0,0,0.3)','bordercolor':'rgba(0,0,0,0.3)',
 'strokWidth0':3,'strokWidth':2,
 'lineColor':'rgba(0,0,0,0.3)','lineWidth':1,'lineDashed':'5,5'
}
var data = {
 text:'前端開發',
 children:[
 {text:'HTML',url:'http://www.cnblogs.com/xiaohuochai/p/5203223.html'},
 {text:'CSS',url:'http://www.cnblogs.com/xiaohuochai/p/5249139.html'},
 {text:'JS',url:'http://www.cnblogs.com/xiaohuochai/p/5613593.html'},
 {text:'ES6',url:'http://www.cnblogs.com/xiaohuochai/p/7233392.html'},
 {text:'HTTP',url:'http://www.cnblogs.com/xiaohuochai/p/6392010.html'},
 {text:'NodeJS',url:'http://www.cnblogs.com/xiaohuochai/p/6940560.html'},
 {text:'前端工具',url:'http://www.cnblogs.com/xiaohuochai/p/6666415.html'},
 ], 
}
addChildenTags();
addCenterTag();
oBox.appendChild(oSvg);
function createTag(tag,objAttr){
 var oTag = document.createElementNS('http://www.w3.org/2000/svg',tag);
 for(var attr in objAttr){
 if(attr == 'xlink:href'){
 oTag.setAttributeNS("http://www.w3.org/1999/xlink",attr,objAttr[attr]);
 }else{
 oTag.setAttribute(attr,objAttr[attr]);
 } 
 } 
 return oTag;
} 
function addCenterTag(){
 var oG = createTag('g',{'style':'cursor:default'});
 var oCircle = createTag('circle',{'cx':appearance.x0,'cy':appearance.y0,'r':appearance.r0,'fill':appearance.bg0,'stroke':appearance.borderColor0,'stroke-width':appearance.strokWidth0});
 var oText = createTag('text',{'x':appearance.x0,'y':appearance.y0,'font-size':appearance.fontSize,'text-anchor':'middle','dominant-baseline':'middle','stroke-width':appearance.strokWidth0});
 oText.innerHTML = data.text;
 oG.appendChild(oCircle);
 oG.appendChild(oText);
 oSvg.appendChild(oG);
}
function addChildenTags(){
 var children = data.children;
 var length = children.length;
 var deg = (360/length)*(2*Math.PI)/360;
 for(var i = 0; i < children.length;i++){
 var cos = Math.cos(deg*i - 90);
 var sin = Math.sin(deg*i - 90);
 var x = appearance.x0 + appearance.dis*cos;
 var y = appearance.y0 + appearance.dis*sin;
 var oA = createTag('a',{'xlink:href':children[i].url,'target':'_black'}); 
 var oG = createTag('g',{'style':'cursor:pointer'}); 
 oG.index = i; 
 var oLine = createTag('line',{'x1':x-appearance.r*cos,y1:y-appearance.r*sin,x2:appearance.x0+appearance.r0*cos,y2:appearance.y0+appearance.r0*sin,'stroke':appearance.lineColor,'stroke-width':appearance.lineWidth,'stroke-dasharray':appearance.lineDashed,'style':'transition:.5s'});
 var oLineHelper = createTag('line',{'x1':x-appearance.r*cos,y1:y-appearance.r*sin,x2:appearance.x0+appearance.r0*cos,y2:appearance.y0+appearance.r0*sin,'stroke':'transparent','stroke-width':10}); 
 var oCircle = createTag('circle',{'cx':x,'cy':y,'r':appearance.r,'fill':appearance.bg,'stroke':appearance.bordercolor,'stroke-width':appearance.strokWidth,'class':'frostedglass'});
 var oText = createTag('text',{'x':x,'y':y,'font-size':appearance.fontSize,'text-anchor':'middle','dominant-baseline':'middle','stroke-width':appearance.strokWidth,fill:appearance.color});
 oText.innerHTML = children[i].text; 
 oG.appendChild(oLine);
 oG.appendChild(oLineHelper); 
 oG.appendChild(oCircle); 
 oG.appendChild(oText);
 oA.appendChild(oG);
 oSvg.appendChild(oA);
 oG.onmouseenter = function(){
 elasticMove(this,appearance.r*1.2);
 var line = this.children[0];
 line.removeAttribute('stroke-dasharray');
 line.setAttribute('stroke-width',appearance.lineWidth*3);
 line.setAttribute('x1',appearance.x0+(appearance.dis - appearance.r0)*Math.cos(deg*this.index - 90));
 line.setAttribute('y1',appearance.y0+(appearance.dis - appearance.r0)*Math.sin(deg*this.index - 90));
 }
 oG.onmouseleave = function(){
 elasticMove(this,appearance.r);
 var line = this.children[0];
 line.setAttribute('stroke-width',appearance.lineWidth);
 line.setAttribute('stroke-dasharray',appearance.lineDashed);
 line.setAttribute('x1',appearance.x0+(appearance.dis - appearance.r)*Math.cos(deg*this.index - 90));
 line.setAttribute('y1',appearance.y0+(appearance.dis - appearance.r)*Math.sin(deg*this.index - 90)); 
 } 
 }
}
function elasticMove(obj,str){
 var circle = obj.getElementsByTagName('circle')[0];
 var r0 = circle.getAttribute('r');
 var r = Number(str);
 //聲明步長值
 var step = 0;
 //聲明彈性距離
 var len = r - r0;
 //聲明彈性系數
 var k = 0.7;
 //聲明損耗系數
 var z= 0.7;
 //聲明當前值
 var cur = r0;
 clearInterval(circle.timer);
 circle.timer = setInterval(function(){
 //獲取當前值cur
 cur = circle.getAttribute('r');
 //更新彈性距離
 len = r - cur;
 //彈力影響
 step += len*k;
 //阻力影響
 step = step*z;
 //賦值
 circle.setAttribute('r',Number(cur) + step);
 //當元素的步長值接近于0，并且彈性距離接近于0時，停止定時器
 if(Math.round(step) == 0 && Math.round(len) == 0){
 circle.setAttribute('r',r);
 clearInterval(circle.timer); 
 } 
 },30);
}
</script>