Question

I have been searching for a long time now on how to do the simplest jQuery validate. (To change border color and background) That’s it, Nothing more! no text or anything extra. I have seen many ways but the code is just too long.

Here’s example of a long code. I dont think its effective way if i had more then 10 fields to validate.

$(document).ready(function(){
//global vars
var form = $("#customform");
var name = $("#name");
var email = $("#email");

//On blur
name.blur(validateName);
email.blur(validateEmail);

//On key press
name.keyup(validateName);

//On Submitting
form.submit(function(){
    if(validateName() & validateEmail())
        return true
    else
        return false;
});

//validation functions
function validateEmail(){
    //testing regular expression
    var a = $("#email").val();
    var filter = /^[a-zA-Z0-9]+[a-zA-Z0-9_.-]+[a-zA-Z0-9_-]+@[a-zA-Z0-9]+[a-zA-Z0-9.-]+[a-zA-Z0-9]+.[a-z]{2,4}$/;
    //if it's valid email
    if(filter.test(a)){
        email.removeClass("error");
        return true;
    }
    //if it's NOT valid
    else{
        email.addClass("error");
        return false;
    }
}
function validateName(){
    //if it's NOT valid
    if(name.val().length < 4){
        name.addClass("error");
        return false;
    }
    //if it's valid
    else{
        name.removeClass("error");
        return true;
    }
}
});

Answer 1

It smells as if you need some refactoring and extract the code that gets repeated all the time into its own function:

function validateElement(element, condition) {
    if(condition){
        element.removeClass("error");
    }
    else {
        element.addClass("error");
    }
    return condition;
}

Use it like this (I also recommend turning your variables into parameters so
that you can use the validators on different fields):

function validateEmail(field) {
    //testing regular expression
    var a = field.val(),
    filter = /^[a-zA-Z0-9]+[a-zA-Z0-9_.-]+[a-zA-Z0-9_-]+@[a-zA-Z0-9]+[a-zA-Z0-9.-]+[a-zA-Z0-9]+.[a-z]{2,4}$/;
    return validateElement(field, filter.test(a));
}

validateEmail($('#email'));