Normally you would modify this so that you could submit or not submit the form based on the number of items selected. Note that in this section we've been using the new ES6 syntax which may not be available in all browsers.
In more complicated forms you will want to set conditions on the form that combine multiple elements.
Radio buttons are implemented as if they were an array of checkboxes.
To find out which value (if any) has been selected, you need to loop through the array until you find which one has been selected: defines a locally scoped variable.
While this cookbook entry focused on doing form validation “by hand”, there are, of course, some great Vue libraries that will handle a lot of this for you.
Switching to a prepackage library may impact the final size of your application, but the benefits could be tremendous.
You can play with this here: See the Pen form validation 3 by Raymond Camden (@cfjedimaster) on Code Pen.
In my final example, we built something that makes use of Ajax to validate at the server.
The code is taken from the Stack Overflow question, How to validate email address in Java Script? This is an awesome question because it makes your most intense Facebook political/religious argument look like a slight disagreement over who makes the best beer. Here is the HTML, even though it’s really close to the first example. You can play with this example here: See the Pen form validation 2 by Raymond Camden (@cfjedimaster) on Code Pen. This tells Vue to cast the value to a number when you use it.
I hope this article is useful for all students and beginners.
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Validating form input with Java Script is easy to do and can save a lot of unnecessary calls to the server.
It can prevent people from leaving fields blank, from entering too little or too much or from using invalid characters.