Something like this can give ideas...
var testString="4644jkljkj.4euu56.yuiyy45"
var textResult=testString.replace(/[^.]+/g,function(a){
if (8<a.length) return '\n'+a+' to long substring';
if (!(/^[A-Za-z]/.test(a))) return '\n'+a+' incorrect first character';
return '\n'+a' ok !';
})
alert(textResult)
Of course tests can be improved. For example alphabetic characters can be defined as [\W\d%]+ (which is alphanumeric without and %).