js渲染数字自增长效果

 1 function renderIncreasingNum(num, fn){
 2     var i = 0,
 3         addUnit = 1,
 4         interv = setInterval(function(){
 5           if(i<100){         
 6              fn.call(null, parseInt(num)-100+i);
 7              i+= addUnit;        
 8           }else{
 9               fn.call(null, num);
10               clearInterval(interv);
11           }
12     }, 10);   
13 }