why use character valication for password code example

Example 1: javascript password validation special character

function CheckPassword(inputtxt) 
{ 
var paswd=  /^(?=.*[0-9])(?=.*[!@#$%^&*])[a-zA-Z0-9!@#$%^&*]{7,15}$/;
if(inputtxt.value.match(paswd)) 
{ 
alert('Correct, try another...')
return true;
}
else
{ 
alert('Wrong...!')
return false;
}
}

Example 2: password validation with regular expression in javascript

var strongRegex = new RegExp("^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#\$%\^&\*])(?=.{8,})");