// function parameters are: field - the string field, count - the field for remaining characters number and max - the maximum number of characters
function CountLeft(field, count, max) {
// if the length of the string in the input field is greater than the max value, trim it
if (field.value.length > max)
field.value = field.value.substring(0, max);
else
// calculate the remaining characters
count.value = max - field.value.length;
}