思路和實現方法都很簡單，只是用的api很少有同學知道。這裡記錄下來。

 1 function getKeyframes(name){
 2             var animation={}
 3             var styleSheets=document.styleSheets
 4             for(var i=0;i<styleSheets.length;i++){
 5                 var item=styleSheets[i];
 6                 if(item.cssRules[0] && item.cssRules[0].name && item.cssRules[0].name==name){
 
 7                     animation.cssRule=item.cssRules[0];
 8                     animation.styleSheet=item;
 9                     animation.index=0;
10                 }
11             }
12             return animation;
13         }

 1 //原生js操作keyframes值
 2         var testDemo=document.getElementById('testDemo');
 
 3         testDemo.onclick=function(){
 4             var arr=[
 5                 {x:0,y:0},
 6                 {x:-16.91,y:-32.36},
 7                 {x:-29.76,y:-55.91},
 8                 {x:-41.19,y:-72.73},
 9                 {x:-52.00,y:-80.00},
10                 {x:-61.38,y:-68.68},
11                 {x:-67.30,y:-52.70},
 
12                 {x:-72.79,y:-33.13},
13                 {x:-78.12,y:-11.13},
14                 {x:-84.00,y:12.00}
15             ];
16             var token = window.WebKitCSSKeyframesRule? '-webkit-':'';
17             let key_name='testDemo'
18             var nameRule=getKeyframes(key_name);
19                 var rules='@'+token+'keyframes '+key_name+'{';
20                 for(var i=0;i<arr.length;i++){
21                     rules+=(i+1)*10+'%{transform:translate3d('+arr[i].x+'px,'+arr[i].y+'px,0);opacity:'+(i+1)*10/100+';}'
22                 }
23                 rules+='}';
24             if(JSON.stringify(nameRule)=='{}'){
25                 var sheet=document.styleSheets[0];
26                 // console.log('````',rules);
27                 sheet.insertRule(rules,0);
28             }else{
29                 nameRule.styleSheet.deleteRule(nameRule.index)
30                 nameRule.styleSheet.insertRule(rules,nameRule.index)
31             }
32             testDemo.style.animation=key_name+' 2s infinite';
33         }