validation in client side with coding example

java script validation in client side with explanation and give an example for 3tier achitecture with simple examples

Kousalya
07 Jul
1749 Views
6 Answers

Amol
07 Jul

JavaScript Form Validation HTML form validation can be done by JavaScript. If a form field (fname) is empty, this function alerts a message, and returns false, to prevent the form from being submitted: Data Validation Data validation is the process of ensuring that user input is clean, correct, and useful. Typical validation tasks are: has the user filled in all required fields? has the user entered a valid date? has the user entered text in a numeric field? Most often, the purpose of data validation is to ensure correct user input. Validation can be defined by many different methods and deployed in many different ways. Server-side validation is performed by a web server after the input has been sent to the server. Client-side validation is performed by a web browser before the input is sent to a web server. HTML Constraint Validation HTML5 introduced a new HTML validation concept called constraint validation. HTML constraint validation is based on: Constraint validation HTML Input Attributes Constraint validation CSS Pseudo Selectors Constraint validation DOM Properties and Methods &lt;!DOCTYPE html&gt; &lt;html&gt; &lt;head&gt; &lt;script&gt; function validateForm() { &nbsp; &nbsp; var x = document.forms[&quot;myForm&quot;][&quot;fname&quot;].value; &nbsp; &nbsp; if (x == &quot;&quot;) { &nbsp; &nbsp; &nbsp; &nbsp; alert(&quot;Name must be filled out&quot;); &nbsp; &nbsp; &nbsp; &nbsp; return false; &nbsp; &nbsp; } } &lt;/script&gt; &lt;/head&gt; &lt;body&gt; &lt;form name=&quot;myForm&quot; action=&quot;/action_page.php&quot; onsubmit=&quot;return validateForm()&quot; method=&quot;post&quot;&gt; Name: &lt;input type=&quot;text&quot; name=&quot;fname&quot;&gt; &lt;input type=&quot;submit&quot; value=&quot;Submit&quot;&gt; &lt;/form&gt; &lt;/body&gt; &lt;/html&gt;

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JavaScript Form Validation
HTML form validation can be done by JavaScript.

If a form field (fname) is empty, this function alerts a message, and returns false, to prevent the form from being submitted:

Data Validation
Data validation is the process of ensuring that user input is clean, correct, and useful.

Typical validation tasks are:

has the user filled in all required fields?
has the user entered a valid date?
has the user entered text in a numeric field?
Most often, the purpose of data validation is to ensure correct user input.

Validation can be defined by many different methods and deployed in many different ways.

Server-side validation is performed by a web server after the input has been sent to the server.

Client-side validation is performed by a web browser before the input is sent to a web server.

HTML Constraint Validation
HTML5 introduced a new HTML validation concept called constraint validation.

HTML constraint validation is based on:

Constraint validation HTML Input Attributes
Constraint validation CSS Pseudo Selectors
Constraint validation DOM Properties and Methods

<!DOCTYPE html>
<html>
<head>
<script>
function validateForm() {
var x = document.forms["myForm"]["fname"].value;
if (x == "") {
alert("Name must be filled out");
return false;
}
}
</script>
</head>
<body>

<form name="myForm" action="/action_page.php"
onsubmit="return validateForm()" method="post">
Name: <input type="text" name="fname">
<input type="submit" value="Submit">
</form>

</body>
</html>

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