javascript - Textbox validations and color change -

i new on java-script.

i have developed system using vs asp.net 4.0 using c#, have more 45 web forms want add validations using java-script. have following code letters , numbers validations. see code below. code doesn't work way want because can validate when press space bar.

function numeralsonly(evt) {     evt = (evt) ? evt : event;     var charcode = (evt.charcode) ? evt.charcode : ((evt.keycode) ? evt.keycode : ((evt.which) ? evt.which : 0));     if (charcode > 31 && (charcode < 48 || charcode > 57)) {         alert("enter numbers in field.");         return false;     }     return true; }  function lettersonly(evt) {     evt = (evt) ? evt : event;     var charcode = (evt.charcode) ? evt.charcode : ((evt.keycode) ? evt.keycode : ((evt.which) ? evt.which : 0));     if (charcode > 31 && (charcode < 65 || charcode > 90) && (charcode < 97 || charcode > 122)) {         alert("enter letters only.");         return false;     }     return true; } 

can please me following;

1.validate numbers , change color of text box red.

2.validate letters only , change color of text box red.

1. validate invalid email address , change color of text box red.

4.validate range of date. e.g if he/she enters invalid date 05/05/2001 ,i need current date.

5.highlight text box red required text box.

for question 5 : call method in onchange or onblur method.it validate, when left field.if want validation on clicking on of key call onkeyup,onkeydown.

   function validations() {   var textbox = document.getelementbyid("textbox1");   if (textbox.value == "") {    textbox.style.bordercolor = "red";    } } 

for question 1:

function namevalidation(){ var nametb = document.getelementsbyname("tb1"); var nameregex = new regexp("^[a-za-z]+$");  var namevalue = nametb.value.trim();  if ((!nameregex.test(namevalue))) {     nametb.style.border = '1px solid red'; } else {     nametb.style.border = "none"; } 

}