Server-side validation is more secure but often more tricky to code, whereas client-side (Java Script) validation is easier to do and quicker too (the browser doesn't have to connect to the server to validate the form, so the user finds out instantly if they've missed out that required field! In this tutorial we'll build a simple form with client-side Java Script validation.
To check, whether the user entered correct form of data, it’s must to apply form validation in any of the form. The expression is: /^[a-z A-Z] $/ The above expression checks whether the input characters in the string is alphabet or not. [A-Z] : It matches characters from uppercase ‘A’ to lowercase ‘Z’. The codes for checking form empty fields are given below: There is an expression that checks whether the string contains only alphabets or not. [a-z] : It matches characters from lowercase ‘a’ to lowercase ‘z’. If by mistake, user skips entering any detail, soon the alert message appear on the form.For example, if your form has a box for the user to type their email address, you might want your form handler to check that they've filled in their address before you deal with the rest of the form.There are two main methods for validating forms: (usually done using Java Script).IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.