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How to Check if Checkbox is Checked in jQuery and JavaScript

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Checkboxes are one of several types of input fields that we use very commonly to allow users to interact with web pages and usually POST data to the backend, by checker Each box applied to a given situation.

Unlike radio buttons (which belong to Radio groups) – Check boxes belonging to a single group Do not contradict each other So a user can choose Multiple boxes Recovered. You must keep this in mind when checking if options have been selected.

In this tutorial, we will review how to check if a check box is selected in jQuery – a popular library for JavaScript, and Vanilla JavaScript.

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Let’s start with a simple check box definition:

<h1>Check if Checkbox is Checked</h1>
<label for="takenBefore">Have you taken this test before?</label>
<input type="checkbox" id="takenBefore" value="Yes">Yes</input>

Pure JavaScript – Checking if a check box is as easy as accessing checked Field, represented by boolean:


checkBox = document.getElementById('takenBefore');

if(checkBox.checked) 
    
    alert("Checkbox checked!");

However, this code will only work if you run it specifically. For example, you can run it when the user submits a form or wants to proceed to the next page as a verification step. Authentication is not usually done this way, and is usually transferred to more powerful libraries. More commonly, you want to respond to the checkbox to change something on the page – such as provide Other Input options.

In these cases, you will want to add Listening to events To the button, and let it listen to events, such as Pressed. When such an event occurs – you can decide to respond to the event:

checkBox = document.getElementById('takenBefore').addEventListener('click', event => 
	if(event.target.checked) 
		alert("Checkbox checked!");
	
);

In this setting – the code is constantly waiting and listening for events in the element! now As soon as someone clicks Check box, yours alert() The method will be performed. This time, however, to achieve the checkBox Element, we purchase it from the event For example, as the target Of the same event.

When you open the page in the browser and press the button, you will be greeted at:

$ (‘# element’)[0].⁇ בָּדוּק⁇

Note: jQuery is a popular JavaScript library, existing in multi Projects around the world. Due to its light weight and features that extend the scope of JavaScript’s built-in capabilities – it has become commodity. Unsurprisingly – it can be used to check if a checkbox is checked or not.

We can use jQuery syntax instead of pure JavaScript to simplify both the element selection and the event listener attached to it.

You can import jQuery to your page using a Content transfer network (CDN). You can also use the jQuery CDN to import the directory.

<script src="https://code.jquery.com/jquery-3.6.0.min.js"
        integrity="sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=" 
        crossorigin="anonymous">
</script>

To check if a check box is selected, in jQuery, you can simply select the element, get its basic object, instead of the jQuery object ([0]) And used the built-in checked attribute:

let isChecked = $('#takenBefore')[0].checked
console.log(isChecked);

Here, we would check if takenBefore The check box is selected, by accessing it through the jQuery switch, and using nate checked Field as before.

Alternatively, you can set a listener to recognize a change:

$('#takenBefore').change(function() 
	alert('Checkbox checked!');
);

This code is much simpler, but works in the same way as the pure JS solution! Clicking on the check box will activate an alert as before:

$ (‘# element’). is (‘: checked’))

Instead of checking through the built-in checked Property – we can lower the logic to is() method. God is() A method is a general method that can be used for many purposes – and returns a true/false Based on the comparison criteria. God :checked The switch is specially created to check whether or not the radio button or check box element is selected.

Therefore, if you combine these together, it is easy to check for a checkbox is(':checked'):

let isChecked = $('#takenBefore').is(':checked');
console.log(isChecked); 

$ (‘# element’). prop (“checked”)

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In earlier versions of jQuery – attr() Used to access and handle fields of elements. In newer versions, the method has been replaced by prop(). It can work as a booster / definer for the properties of elements, and in our case – as a wrapper for making checked Feature of an element.

let isChecked = $('#takenBefore').prop('checked');
console.log(isChecked); 

he() Vs to support()?

So what is the difference between them is() and prop() In this context?

Both methods seem to work the same way from our point of view. So what’s the difference?

is() There is a little more processing and overhead analysis than that prop(). Even given the fact that prop() No only Access to property and makes Some Verification, it’s more performance when it comes to processing multiple inputs, for example, in a loop.

On the other hand – is() Always returns a boolean Value, while prop() Just returns the basic property type. You can not guarantee that something else has crept in, and your code may fail while running if you do not use prop() Properly. is() also Demonstrates semantically Return value – a boolean, Making it a more readable option.

Summary

In this short tutorial, we looked at how to check if the check box is checked with JavaScript and jQuery.

We used checked Property – directly and indirectly, followed by the is() and prop() Methods as well as take a quick look at what you might prefer.

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