javascript方法(两个日期相减得到年的差值)

 
alert(dateDiffYear("1980-4-1","1982-3-30"));     
  
function   dateDiffYear(dateStart,dateEnd)   
  {   
  var   arr1   =   dateStart.split("-");   
  var   arr2   =   dateEnd.split("-");   
  var   year   =   arr2[0]   -   arr1[0];     
  if(arr2[1]>=arr1[1]   &&   arr2[2]>=arr1[2]-1)   
  { return   year;}   
  else     
  { if(arr1[2]==1)   
  {   
  if((arr2[1]==1   ||   arr2[1]==3   ||   arr2[1]==5   ||   arr2[1]==7   ||   arr2[1]==8   ||   arr2[1]==10   ||   arr2[1]==12)   &&   arr2[2]==31)   
  return   year;   
  if((arr2[1]==4   ||   arr2[1]==6   ||   arr2[1]==9   ||   arr2[1]==11)   &&   arr2[2]==30)   
  return   year;   
  if(arr2[1]==2)   
  if((arr2[0]%4   ==   0   &&   arr2[0]%100   !=   0||   arr2[0]%100   ==   0   &&   arr2[0]%400   ==   0)   &&   arr2[2]==29)   
  return   year;   
  else   if((arr2[0]%4   !=   0   ||   arr2[0]%100   ==   0)   &&   arr2[2]==28)   
  return   year;   
  else   
  return   year-1   
  }   
  return   year-1;   
  }   
  }