Require input if there are any [duplicate]

1. How to prevent duplicate entry in JavaScript?
2. How do you allow duplicate values in a set?
3. How to check duplicate values in textbox using javascript?
4. How to check duplicate email in JavaScript?

How to prevent duplicate entry in JavaScript?

Javascript filter() Method: The filter() method creates a new array of elements that pass the condition we provide. It will include only those elements for which true is returned. We can remove duplicate values from the array by simply adjusting our condition.

How do you allow duplicate values in a set?

Set is not allowed to store duplicated values by definition. If you need duplicated values, use a List. As specified on the documentation of the interface, when you try to add a duplicated value, the method add returns false, not an Exception.

How to check duplicate values in textbox using javascript?

You can refresh the value attribute using $(this). attr('value', $(this). val()); first, then check if there's any other field with class selector has the same value using value selector $('. selector[value="' + current_value + '"]').

How to check duplicate email in JavaScript?

keyup(function() //Get input fields values var $email1 = $("input[name='email']"). val(); var $email2 = $("input[name='confirmEmail']"). val(); //Check if email are identical. if($email1 === $email2) console.