function IteratorField(){
	var field = null;
	var fieldId = "";
	var displayId = "";
	var display = null;
	var limit = 1000;
	var cont = 0;
	
	
	this.iterate = function(){
		display.innerHTML = field.value.length;
		if(field.value.length >= limit){
			alert("Este campo não pode ter mais que " + limit + " caracteres");
			field.value = field.value.substring(0,field.value.length-1);
		}
	} 
	this.init = function(){
		field = document.getElementById(this.fieldId);
		display = document.getElementById(this.displayId);
		field.onkeypress = this.iterate;
	}
}