JavaScript Basics

JavaScript is a dynamic programming language. It is most commonly used as part of web browsers, whose implementations allow client-side scripts to interact with the user, control the browser, communicate asynchronously, and alter the document content that is displayed.

Advantages of using JavaScript

Ø  Form validation can be done on the client side, which reduces the unnecessary round trips between the client and the server. This also means the load on the server is reduced and the application is more responsive.

Ø  JavaScript uses the client machine processing power.

Ø  With JavaScript partial page updates are possible i.e only portions of the page can be updated, without reloading the entire web form. This is commonly called as AJAX.

Ø  JavaScript can also be used to animate elements on a page. For example, show or hide elements and sections of the page.

Disadvantages of JavaScript

Ø  Security: JavaScript runs on the client machine. So a malicious user may use JavaScript to do a variety of things like tracking your browsing history, stealing passwords etc. This is one of the main reasons why people disable JavaScript.

Ø  Browser Compatibility: Not all browsers treat the same piece of JavaScript in the same manner. This means the functionality and the user interface may vary from browser to browser. That is why cross-browser testing is very important. However, with JavaScript libraries like jQuery Browser Compatibility is no longer a major issue.

Why Client side and Server side validation require?

If we have disabled JavaScript, then it will bypass the client side validation and we also don't have any server side method validating the form. This is one of the reasons why we always want to have both client side and server side validation.

If JavaScript is disabled and if we don't have any server side validation, there could be different threats ranging from storing invalid data to security vulnerabilities.

Client-side validation provides better user experience as it reduces the unnecessary round trips between the client and the server. So client side validation is nice to have.

However, if JavaScript is disabled or if the user is making a request using tools like fiddler we still want to validate the form before saving data. So, server side validation should always be there irrespective of whether we have client side validation or not.