More and more browsers now support the constraint validation API, and it's becoming reliable.
This API consists of a set of methods and properties available on each form element.
If correct, the application allows the data to be submitted to the server and (usually) saved in a database; if not, it gives you error messages to explain what you've done wrong (provided you've done it right).
Form validation can be implemented in a number of different ways.
For numeric fields, there is a convenient way to validate a value range, but we want to select to run a custom validation script.
After the “Edit” button is clicked, a new window will open that allows us to edit the new script: This script also includes a check for an empty string, so that the user can wipe out a wrong string and start from scratch.
One of the features of HTML5 is the ability to validate most user data without relying on scripts.
This is done by using validation attributes on form elements, which allow you to specify rules for a form input like whether a value needs to be filled in, the minimum and maximum length of the data, whether it needs to be a number, an email address, or something else, and a pattern that it must match.
So, having a text field contain that error message might be a good idea.There are other ways to highlight the field in question besides changing the text color, the border color or the fill color could be changed instead, or in addition, just make sure that you are not making the form impossible to read.To learn more about the event object, take a look at JS.88.560– make sure to click on the button in the upper left corner to display the navigation pane if it’s not shown automatically.Form validation helps us achieve these goals — this article tells you what you need to know.This is called form validation — when you enter data, the web application checks it to see if it is correct.attribute to turn off the browser's automatic validation; this lets our script take control over validation.