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JavaScript

Index

Form & component validation

Javascript Form Validation

PHP Advance Form validation code

PHP form validation is a frequent requirement in many applications. Different type of php form validations is used based on the requirements but the process remains same. Let us start with a simple one and then go to the complex email validation using PHP regular expression.

Let us keep an input box and we will not allow any user to enter null data in it. So our form validation script will check for null entry and do the processing accordingly. Our main page where form is there is called form.php and let us posts the data to another page and name it as form_validate.php. We will check and validate the variables in form_validate.php page. Here is the simple html form.

On submit of this form all entered variables will be available on form_validate.php page so let us go to form_validate.php page and read the variable and check if any value is there or not. Let us use one flag to check the status of the variables for form validation.

<?php

$flag="OK"; // This is the flag and we set it to OK
$msg=""; // Initializing the message to hold the error messages

if(strlen($userid) < 5){ // checking the length of the entered userid and it must be more than 5 character in length
$msg=$msg."( Please enter user id more than 5 character length )<BR>";
$flag="NOTOK"; //setting the flag to error flag.
}

User id validation is over, now let us start password checking.

if(strlen($password) < 5 ){ // checking the length of the entered password and it must be more than 5 character in length
$msg=$msg."( Please enter password of more than 5 character length )<BR>";
$flag="NOTOK"; //setting the flag to error flag.
}

Now let us check the flag and give message accordingly, if the flag is set to OK then all validations is passed and we can proceed for the database checking. If the flag is set to NOTOK then entries are not ok so we have to display the messages. We also give one back button for the user to go back and correct the entries.

if($flag <>"OK"){
echo "<center>$msg <br> <input type='button' value='Retry' onClick='history.go(-1)'></center>";
}else{ // all entries are correct and let us proceed with the database checking etc …
}

This is PHP form validation by using two simple text boxes. We have checked only the number of characters entered by the user. Now let us move one more step and go for form validation checking the type of entry. Say in userid field other than characters are not allowed. We will use same flag to set the status and append the message to the message variable.

if(ereg('[^A-Za-z]', $userid)){ //Only lower or upper case letters allowed.
$msg=$msg."( Please use only alphabets a to z as userid )<BR>";
$flag="NOTOK"; //setting the flag to error flag.
}

Validation (checking ) of period button on submit of Form

Period buttons are used when the visitor has to select one of the many options available. For example in a signup form the visitor has to select the sex by clicking on Male or Female selection. In different cases there can be more than two options also. For example mode of payment can be any one of the options saying cash, check, draft, credit card, or wire transfer. We can select one of the options out of many choices. We can check or validate the submission by checking any selection is made or not. The form will not be submitted if no selection is made.

Please note that we will be using client side JavaScript validation so if the user browser has disabled JavaScript then we can't detect the status of the selection by the user and the form will simply submit. For this reason many scripts use server side validations. In server side validation the data has to go and return from server so it takes time. JavaScript validation in client side is fast and we also can detect the JavaScript setting of the browser and redirect the visitor or give a warning message asking to enable JavaScript.

Validation (checking ) of checkbox selection on submit of Form

Check box is used to get user inputs within the form. A group of checkbox is used or a single check box is used to collect the options of the visitor. The difference in check box and period button is the user can't select more than one option in case of period buttons. In checkbox the user can give more than one option. For example in a newsletter script you can ask the visitor to select their interested areas. Here the user can give one or more than one are as the area of interest. So all options are to be stored or covered for the user. This way we can get more than one option for a choice. Here we will try with one checkbox and in another tutorial we will consider more than one checkbox.

In signup forms you will see one checkbox asking you to read the term and condition of the site and the user must agree to this by selecting a checkbox. On submit of the form the status of this checkbox is checked and if not checked by the user then alert message is displayed saying the user has to agree to the terms and conditions.

The JavaScript code is kept within the head tag of the page. See the validation

Checkbox Array in a Form

Checkboxes can be used as arrays and the value can be collected using JavaScript. We will be discussing client side JavaScript and the collection of checkbox value. You can visit the php section for checkbox array handling using PHP server side scripting. We can create a group of checkbox by giving them the same name and that will create an array and from it we can collect the names of the check boxes for which it is checked.

Here are some commands we will be using to get the details of the events or actions we perform.

document.form1.scripts.length

This gives us the length of the array or the number of elements present in the array. If we know we are using 5 checkboxes then we can directly use the number 5 but it is a good to use this as this picks up all the checkboxes of the group without missing any thing. Note that the word scripts in the document.form1.scripts.length is the name of the array and same as the checkboxes name.

The JavaScript code is kept within the head tag of the page.

<script type="text/javascript">
function validate(form) {
// Checking if at least one period button is selected. Or not.
if (!document.form1.sex[0].checked && !document.form1.sex[1].checked){

alert("Please Select Sex"); return false;}

var total=""
for(var i=0; i < document.form1.scripts.length; i++){
if(document.form1.scripts[i].checked)
total +=document.form1.scripts[i].value + "\n"
}
if(total=="")
alert("select scripts") else
alert (total)

return false;
} </script>

To display the period button and checkboxes see the code below.

<table border='0' width='50%' cellspacing='0' cellpadding='0' ><form name=form1 method=post action=action_page.php onsubmit='return validate(this)'><input type=hidden name=todo value=post>

<tr bgcolor='#ffffff'><td align=center ><font face='verdana' size='2'><b>Sex</b><input type=radio name=sex value='male'>Male </font><input type=radio name=sex value='female'><font face='verdana' size='2'>Female</font></td></tr>

<tr><td align=center bgcolor='#f1f1f1'><font face='verdana' size='2'><b>Scripts You know</b><input type=checkbox name=scripts value='JavaScript'>JavaScript <input type=checkbox name=scripts value='PHP'>PHP <input type=checkbox name=scripts value='HTML'>HTML </td></tr>

<tr bgcolor='#ffffff'><td align=center ><input type=submit value=Submit> <input type=reset value=Reset></td></tr>

</table></form>

Check or Uncheck all in a group of checkbox in JavaScript

If we have a series or a group of check boxes then we can provide one button to check all the checkboxes at one go and another button to uncheck all the checked buttons by using client side JavaScript. This way the user in a single attempt can check or uncheck all the buttons. Note that this is a client side JavaScript feature so JavaScript execution is to be enabled in the client browser.

There are different ways to achieve this result; we can keep two buttons for this. One button will check all the checkboxes and other button will uncheck all the buttons. The same result we can achieve by using a single buttons also. We can also keep one checkbox to get the same functionality. When we check the single checkbox we can make all the checkboxes checked and by uncheck we can make all the checkboxes uncheck( Inside mailbox of hotmail.com you can see this ) . Let us start with two buttons first. One for check all and other for Uncheck all .

Here is the JavaScript function to be kept within the head tag

This is the HTML code to be kept inside the body tag.

<form name="myform" action="checkboxes.asp" method="post">
<b>Scripts for Web design and programming</b><br>
<input type="checkbox" name="check_list" value="1">ASP<br>
<input type="checkbox" name="check_list" value="2">PHP<br>
<input type="checkbox" name="check_list" value="3">JavaScript<br>
<input type="checkbox" name="check_list" value="4">HTML<br>
<input type="checkbox" name="check_list" value="5">MySQL<br>

<input type="button" name="Check_All" value="Check All"
onClick="CheckAll(document.myform.check_list)">
<input type="button" name="Un_CheckAll" value="Uncheck All"
onClick="UnCheckAll(document.myform.check_list)">

Here is the code for single button. Here is the single function we use inside our head tags.

Now the html part

Here is the code for head part of the script

Here is the code for body part .

<form name="myform" action="checkboxes.asp" method="post">
<b>Scripts for Web design and programming</b><br>
<input type="checkbox" name="check_list" value="1">ASP<br>
<input type="checkbox" name="check_list" value="2">PHP<br>
<input type="checkbox" name="check_list" value="3">JavaScript<br>
<input type="checkbox" name="check_list" value="4">HTML<br>
<input type="checkbox" name="check_list" value="5">MySQL<br>

<input type="checkbox" name="Check_ctr" value="yes"
onClick="Check(document.myform.check_list)"><b>Check Control</b>

</form>

Enable and disable of text box through a checkbox

We may need to enable or disable a text box based on the input of the user by using disabled property of the element. For example we have some choices for the visitor and one of the options is Others. Once the visitor select the others options then ( only ) one text box will be enabled to allow the visitor to fill the details.

Here is the demo of this. Click the checkbox to enable or disable the text box.

We have used the body onload command to keep the text area disabled while the page is loading.

The full code is here.

<html>
<head>
<title>(Type a title for your page here)</title>
<script language="JavaScript">

</script>
</head>
<body onload=enable_text(false);>

<form name=f1 method=post>
<input type="checkbox" name=others onclick="enable_text(this.checked)" >Others
<input type=text name=other_text>
</form>

</body>
</html>

Adding options to List Box in client side Javascript

Options to a drop down list box can be added dynamically using client side JavaScript. We will discuss a simple way of adding options to a list. The process of adding can be controlled based on different condition required. Depending on conditions options can be removed also.

Here we will take care that the options are added on the page load , so by default the list box is pre populated when the page is displayed. You can see the demo at the end of this page. The main function creates a new OPTION object and assigns values and text part of the option. Here is the function which collects the list box name, value and text as inputs and then adds the option to the list box. Here is the function

function addOption(selectbox,text,value )
{
var optn = document.createElement("OPTION");
optn.text = text;
optn.value = value;
selectbox.options.add(optn);
}

Note that each time the function is called, it adds a new option to the list box. So we can add one option by calling the function once. Like this.

addOption(document.drop_list.Month_list,”January”, “January”);

So this way we can create a drop down list box of all the months by calling the function each time for a month. So with this now you can easily create the list box. But we will add another step to this by using one array of months. So from the array of months we will loop through and add each month to the list box. Here is how to create the array

var month = new Array("January","February","March","April","May","June",
"July","August","September","October","November","December");

So now once our array is ready with data, we will loop through the array by using for loop and then call the addOption function using the data of the array. Here is the code.

for (var i=0; i < month.length;++i){

addOption(document.drop_list.Month_list, month[i], month[i]);
}

You can see with this array we will able to populate the drop down list box of months. Here is the simple code for html body tag and the form with drop down list

<body bgcolor="#ffffff" text="#000000" link="#0000ff" vlink="#800080"
alink="#ff0000" onLoad="addOption_list()";>

<FORM name="drop_list" action="yourpage.php" method="POST" >

<SELECT NAME="Month_list">
<Option value="" >Month list</option>
</SELECT>
</form>

</body>

Removing options from a List Box in client side Javascript

We can remove the options from a list box by using client side JavaScript. You can see the article explaining how to add options to a list box using JavaScript. Here we will discuss on how to remove option on selection and removing all the options in one go. We will use different functions and connect them to buttons to execute them. Here are some functions and there uses in removing the options. You can see the demo of this program here.

While the page loads we will try to populate the list box by using onload event of the body tag. The list box will be filled with data at the time of display to the visitors. The detail on how to add options to list box you can get here. So we will go to the next step

Removing all the options
To remove all the options from the list box we will loop through all the elements of the list box and remove one by one. We will use for loop to loop from 0 to selectbox.options.length-1. The total length ( or the number of elements ) of the array we can get by using selectbox.options.length and to this we are subtracting 1 as the first elements starts from 0 ( not from 1 ). Here is the function

function removeAllOptions(selectbox)
{
var i;
for(i=selectbox.options.length-1;i>=0;i--)
{
selectbox.remove(i);
}
}

The for loop will remove all the elements with the value of i changing from last element of the array to first element of the array.

Removing Selected Options
We can remove the options one by one or by selecting more than one option and then by pressing the button. Here also we will use the similar function like above but before deleting we will check if the option is checked or not. selectbox.options[i].selected will return true if the option is selected. This way we will check all the elements of the list box and if they are checked then we will add the command selectbox.options.remove(i); to remove that particular option from the list box. Here is the function.

function removeOptions(selectbox)
{
var i;
for(i=selectbox.options.length-1;i>=0;i--)
{
if(selectbox.options[i].selected)
selectbox.remove(i);
}
}

Adding the options
There is a full tutorial on adding the options to list box. So here is the function.

function addOption(selectbox,text,value )
{
var optn = document.createElement("OPTION");
optn.text = text;
optn.value = value;
selectbox.options.add(optn);
}

function addOption_list(selectbox){
addOption(document.drop_list.SubCat, "One","One");
addOption(document.drop_list.SubCat, "Two","Two");
addOption(document.drop_list.SubCat, "Three","Three");
addOption(document.drop_list.SubCat, "Four","Four");
addOption(document.drop_list.SubCat, "Five","Five");
addOption(document.drop_list.SubCat, "Six","Six");

}

Now we will see how the select box with the form and buttons are placed in the body are of the page. Each button is connected to one function with on click event handler. See here

<FORM name="drop_list" action="yourpage.php" method="POST" >

<SELECT id="SubCat" NAME="SubCat" MULTIPLE size=6 width=10>
</SELECT><br>
<input type=button onClick="removeOptions(SubCat)"; value='Remove Selected'>
<input type=button onClick="removeAllOptions(SubCat)"; value='Remove All'>
<input type=button onClick="addOption_list()"; value='Add All'>

</form>

Transferring options from one multiple selection boxes to other

We can transfer options from one selection box to other by selecting one by one or at one go. The uses of such a type of selection are you can select more than one options and it offers a better picture than selecting a group of checkboxes. To get an idea how the script works, see the demo at the end of this page. You can download the page with this code also.

This tutorial explains on how to move elements from one list to other, there are one more tutorial where the second list options are dynamically added or generated based on the selection of the first list.

You can see there are four main functions the page does and each is connected to one button. All the buttons have onlick event handler connected to one function. The page on load calls one function adoption_all_list() through the body tag to populate the first drop down box with default values. There are tutorials on adding elements or options to a list box to know how the function works. There is another tutorial on removing options from the list box. You must read these two tutorials before reading this. So out of the four buttons we will discuss the button which moves the selected options from first list box to second list box. For other functions refer to those adding and removing option tutorials.

The function we will discuss is addOption_list(), it moves the selected options to the second list box. On execution of this function it collects the elements selected, to do this a for loop is used which loops through all the options of the first list box. The line

for(i=document.drop_list.Category.options.length-1;i>=0;i--)

does that. While inside the loop we can get the status of any element by checking selected event and it returns true if the element is selected. Then we can use if condition to get the status.

if(document.drop_list.Category[i].selected)
So if it is selected then we have to execute two steps ( inside the above if condition ) first we will add the option to second drop down list and then remove it from first list. Here are the two steps.

addOption(document.drop_list.SubCat, document.drop_list.Category[i].value, document.drop_list.Category[i].value);
removeOption(Category,i);

The first step uses addOption function to insert the option and the second step uses removeOption function to remove that element from fist list box.

Here is the full function code for moving elements from one drop down to second drop down.

function addOption_list(){
for(i=document.drop_list.Category.options.length-1;i>=0;i--) {
var Category=document.drop_list.Category;
if(document.drop_list.Category[i].selected){
addOption(document.drop_list.SubCat, document.drop_list.Category[i].value, document.drop_list.Category[i].value);
removeOption(Category,i);
}
}
}

Here is the html code to display the drop down boxes and the buttons.

<body onload="addOption_all_list()" ;="" alink="#ff0000" bgcolor="#ffffff" link="#0000ff" text="#000000" vlink="#800080">

<form name="drop_list" action="yourpage.php" method="post">
<input onclick="addOption_all_list()" ;="" value="Add All" type="button">

<select name="Category" multiple="multiple" size="7">
<option value="PHP">PHP</option>
<option value="ASP">ASP</option>
<option value="JavaScript">JavaScript</option>
<option value="HTML">HTML</option><option value="Perl">Perl</option><option value="MySQL">MySQL</option></select>
<input onclick="addOption_list()" ;="" value="Move >" type="button"> <input onclick="move_all_Option()" ;="" value="Move All >>" type="button"> <select id="SubCat" name="SubCat" multiple="multiple" size="7"></select><input onclick="removeAllOptions(SubCat)" ;="" value="Remove All" type="button">
</form>

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