Try using arrayname.toString().length;

browser alerts will always come with a javascript header. But for the cancel part you can always use return false, which will prevent the user from submitting the form.

Hello, You can use confirm("your text"); It comes with a ok and cancel button.   Please Mark as correct answer if found useful.

Hello,   You can create these by changing the attributes of the variable. Right click on the variable name and configure the dictionary , then set the attributes for the variable. PLEASE HIT LIKE OR MARK HELPFUL IF FOUND USEFUL.