函数中的Javascript开关用法

Question

Here is my javascript function which replaces "yyyy" of a date format with "yy" and replaces "yy" with "y" example

    validateDateFormat("dd/mm/yyyy") gives "dd/mm/yy"
    validateDateFormat("dd/mm/yy") gives "dd/mm/y"

Here is my js function

function validateDateFormat(format) { 
    var index =  format.indexOf("yyyy");    
    if(index <0 )
     {    var index =  format.indexOf("yy");    
          if(index <0 )
             return format;
          else
               return format = format.substring(0, index) + format.substring(index+1);          
     }
    else 
        return format = format.substring(0, index) + format.substring(index+2);
}

Am trying to re-write the function with switch or make it recursive, is it doable?

Answer 1

I guess You want something like this?

function validateDateFormat(s)
{
    if(s.indexOf('yyyy') > -1)
      return s.replace('yyyy','yy');

    return s.replace('yy','y');
}

alert(validateDateFormat('dd/mm/yyyy')); // "dd/mm/yy"
alert(validateDateFormat('dd/mm/yy')); // "dd/mm/y"

Fiddle