Checkbox in JavaScript

Check all button html

Note: Radio buttons are similar to checkboxes, but with an important distinction — same-named radio buttons are grouped into a set in which only one radio button can be selected at a time, whereas checkboxes allow you to turn single values on and off. Where multiple same-named controls exist, radio buttons allow one to be selected out of them all, whereas checkboxes allow multiple values to be selected.

Value

A string representing the value of the checkbox. This is not displayed on the client-side, but on the server this is the value given to the data submitted with the checkbox’s name . Take the following example:

form> div> input type="checkbox" id="subscribeNews" name="subscribe" value="newsletter" /> label for="subscribeNews">Subscribe to newsletter?label> div> div> button type="submit">Subscribebutton> div> form> 

In this example, we’ve got a name of subscribe , and a value of newsletter . When the form is submitted, the data name/value pair will be subscribe=newsletter .

If the value attribute was omitted, the default value for the checkbox is on , so the submitted data in that case would be subscribe=on .

Note: If a checkbox is unchecked when its form is submitted, neither the name nor the value is submitted to the server. There is no HTML-only method of representing a checkbox’s unchecked state (e.g. value=unchecked ). If you wanted to submit a default value for the checkbox when it is unchecked, you could include JavaScript to create a within the form with a value indicating an unchecked state.

Additional attributes

A boolean attribute indicating whether this checkbox is checked by default (when the page loads). It does not indicate whether this checkbox is currently checked: if the checkbox’s state is changed, this content attribute does not reflect the change. (Only the HTMLInputElement ‘s checked IDL attribute is updated.)

Note: Unlike other input controls, a checkbox’s value is only included in the submitted data if the checkbox is currently checked . If it is, then the value of the checkbox’s value attribute is reported as the input’s value, or on if no value is set. Unlike other browsers, Firefox by default persists the dynamic checked state of an across page loads. Use the autocomplete attribute to control this feature.

Using checkbox inputs

We already covered the most basic use of checkboxes above. Let’s now look at the other common checkbox-related features and techniques you’ll need.

Handling multiple checkboxes

The example we saw above only contained one checkbox; in real-world situations you’ll be likely to encounter multiple checkboxes. If they are completely unrelated, then you can just deal with them all separately, as shown above. However, if they’re all related, things are not quite so simple.

For example, in the following demo we include multiple checkboxes to allow the user to select their interests (see the full version in the Examples section).

fieldset> legend>Choose your interestslegend> div> input type="checkbox" id="coding" name="interest" value="coding" /> label for="coding">Codinglabel> div> div> input type="checkbox" id="music" name="interest" value="music" /> label for="music">Musiclabel> div> fieldset> 

In this example you will see that we’ve given each checkbox the same name . If both checkboxes are checked and then the form is submitted, you’ll get a string of name/value pairs submitted like this: interest=coding&interest=music . When this string reaches the server, you need to parse it other than as an associative array, so all values, not only the last value, of interest are captured. For one technique used with Python, see Handle Multiple Checkboxes with a Single Serverside Variable, for example.

Checking boxes by default

To make a checkbox checked by default, you give it the checked attribute. See the below example:

fieldset> legend>Choose your interestslegend> div> input type="checkbox" id="coding" name="interest" value="coding" checked /> label for="coding">Codinglabel> div> div> input type="checkbox" id="music" name="interest" value="music" /> label for="music">Musiclabel> div> fieldset> 

Providing a bigger hit area for your checkboxes

Beyond accessibility, this is another good reason to properly set up elements on your forms.

Indeterminate state checkboxes

In addition to the checked and unchecked states, there is a third state a checkbox can be in: indeterminate. This is a state in which it’s impossible to say whether the item is toggled on or off. This is set using the HTMLInputElement object’s indeterminate property via JavaScript (it cannot be set using an HTML attribute):

A checkbox in the indeterminate state has a horizontal line in the box (it looks somewhat like a hyphen or minus sign) instead of a check/tick in most browsers.

There are not many use cases for this property. The most common is when a checkbox is available that «owns» a number of sub-options (which are also checkboxes). If all of the sub-options are checked, the owning checkbox is also checked, and if they’re all unchecked, the owning checkbox is unchecked. If any one or more of the sub-options have a different state than the others, the owning checkbox is in the indeterminate state.

This can be seen in the below example (thanks to CSS Tricks for the inspiration). In this example we keep track of the ingredients we are collecting for a recipe. When you check or uncheck an ingredient’s checkbox, a JavaScript function checks the total number of checked ingredients:

• If none are checked, the recipe name’s checkbox is set to unchecked.
• If one or two are checked, the recipe name’s checkbox is set to indeterminate .
• If all three are checked, the recipe name’s checkbox is set to checked .

So in this case the indeterminate state is used to state that collecting the ingredients has started, but the recipe is not yet complete.

const overall = document.querySelector("#enchantment"); const ingredients = document.querySelectorAll("ul input"); overall.addEventListener("click", (e) =>  e.preventDefault(); >); for (const ingredient of ingredients)  ingredient.addEventListener("click", updateDisplay); > function updateDisplay()  let checkedCount = 0; for (const ingredient of ingredients)  if (ingredient.checked)  checkedCount++; > > if (checkedCount === 0)  overall.checked = false; overall.indeterminate = false; > else if (checkedCount === ingredients.length)  overall.checked = true; overall.indeterminate = false; > else  overall.checked = false; overall.indeterminate = true; > > 

Note: If you submit a form with an indeterminate checkbox, the same thing happens as if the checkbox were unchecked — no data is submitted to represent the checkbox.

Validation

Checkboxes do support validation (offered to all s). However, most of the ValidityState s will always be false . If the checkbox has the required attribute, but is not checked, then ValidityState.valueMissing will be true .

Examples

The following example is an extended version of the «multiple checkboxes» example we saw above — it has more standard options, plus an «other» checkbox that when checked causes a text field to appear to enter a value for the «other» option. This is achieved with a simple block of JavaScript. The example includes implicit labels, with the directly inside the . The text input, without a visible label, includes the aria-label attribute which provides its accessible name. This example also includes some CSS to improve the styling.

HTML

form> fieldset> legend>Choose your interestslegend> div> label> input type="checkbox" id="coding" name="interest" value="coding" /> Coding label> div> div> label> input type="checkbox" id="music" name="interest" value="music" /> Music label> div> div> label> input type="checkbox" id="art" name="interest" value="art" /> Art label> div> div> label> input type="checkbox" id="sports" name="interest" value="sports" /> Sports label> div> div> label> input type="checkbox" id="cooking" name="interest" value="cooking" /> Cooking label> div> div> label> input type="checkbox" id="other" name="interest" value="other" /> Other label> input type="text" id="otherValue" name="other" aria-label="Other interest" /> div> div> button type="submit">Submit formbutton> div> fieldset> form> 

CSS

html  font-family: sans-serif; > form  width: 600px; margin: 0 auto; > div  margin-bottom: 10px; > fieldset  background: cyan; border: 5px solid blue; > legend  padding: 10px; background: blue; color: cyan; > 

JavaScript

const otherCheckbox = document.querySelector("#other"); const otherText = document.querySelector("#otherValue"); otherText.style.visibility = "hidden"; otherCheckbox.addEventListener("change", () =>  if (otherCheckbox.checked)  otherText.style.visibility = "visible"; otherText.value = ""; > else  otherText.style.visibility = "hidden"; > >); 

Technical summary

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• :checked , :indeterminate : CSS selectors that let you style checkboxes based on their current state
• HTMLInputElement : HTML DOM API that implements the element
• CSS property compatibility table for form controls

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This page was last modified on Jun 13, 2023 by MDN contributors.

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Check or Uncheck all in a group of checkbox in JavaScript

If we have a series or a group of check boxes then we can provide one button to check all the checkboxes at one go and another button to uncheck all the checked buttons by using client side JavaScript. This way the user in a single attempt can check or uncheck all the buttons. Note that this is a client side JavaScript feature so JavaScript execution is to be enabled in the client browser.

Check all checkboxes or Un check all by using single or double buttons or checkbox in JavaScript

There are different ways to achieve this result; we can keep two buttons for this. One button will check all the checkboxes and other button will uncheck all the buttons. The same result we can achieve by using a single buttons also. We can also keep one checkbox to get the same functionality. When we check the single checkbox we can make all the checkboxes checked and by uncheck we can make all the checkboxes uncheck( Inside mailbox of hotmail.com you can see this ) . Let us start with two buttons first. One for check all and other for Uncheck all .
Demo of Checkbox checkall uncheckall →
Here is the JavaScript function to be kept within the head tag

  function UnCheckAll(chk) < for (i = 0; i < chk.length; i++) chk[i].checked = false ; >// End --> 

This is the HTML code to be kept inside the body tag.

Scripts for Web design and programming
ASP
PHP
JavaScript
HTML
MySQL

Managing form with backed PHP script to receive data

After displaying a group of checkboxes having same name, we can send the data to back end scirpt ( PHP here ) for further processing. This is part of a form so other elements like text box , radio buttons etc can be added to the form.

      ASP 
PHP 
JavaScript 
HTML 
MySQL 
 Check Control  

PHP script to receive array with selected options. Displaying the values of only checked check boxes.

"; echo "Back to form"; $str=''; echo "
Following elements are checked 
"; while (list ($key,$val) = @each ($scripts)) < $str=$str. "$val,"; >echo $str; ?>

Using JQuery

We can get similar result by using JQuery. The advantage less code as we will be using JQuery library. Read more on Jquery Checkbox.

Restricting user selections

We can ask the user to select from a group of checkboxes but we can add one limit to the number of selections by user. User can change the selection but can’t exceed the limit.
Limiting number of Checkboxes user can select →
← JavaScript Checkbox Reference

plus2net.com

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