var model = new Array;
var e = 'element';

function manage_field_length(field_id, max_length) {
	if (model[field_id] == null) {
		model[field_id] = new Array;
		model[field_id][e] = document.getElementById(field_id);
	}
	if (model[field_id][e] == null) { // check one more time, in case it was overwritten somehow
		model[field_id][e] = document.getElementById(field_id);
	}


	if (model[field_id][e] == null) {
		return false;
	}
	
	if (model[field_id][e].value != null && model[field_id][e].value.length > max_length) {
		model[field_id][e].value = model[field_id][e].value.substr(0, (max_length - 1));
		window.alert('This field allows only ' + max_length + ' characters.');
		return model[field_id][e].value.length;
	}

	return true;
}