Javascript check duplicate input

1. How to check duplicate entries in JavaScript?
2. How to check duplicate values in textbox using javascript?
3. How to prevent duplicate entry in JavaScript?
4. How to check duplicate email in JavaScript?

How to check duplicate entries in JavaScript?

Using the filter() and indexOf() Methods

This is the shortest and the easiest way of finding duplicates in an array, where the filter() method traverses the array and filters items according to the defined condition and returns a new array, while the indexOf() gives the index of the passed item.

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 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 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.