January 14, 2016

How to Check a Checkbox Using JavaScript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to check a checkbox using javascript. A checkbox is a tiny square that you can check or uncheck. Checkboxes are used whenever you want to provide a limited number of choices to a user.

Whenever you check a checkbox, a tick symbol appears on top of it and that means whatever the statement or word is written right next to it, you are agreeing or approving that. This is generally done by clicking on the checkbox with the help of the left button on the mouse.

The input element can be of different types and one of them is the checkbox. When the type of input element is a checkbox, we have access to the checked property. This property returns a Boolean value depending upon the status of the checkbox. Also, it can be used to check or uncheck the checkbox.

In the following example, we are going to check a checkbox dynamically upon button click. Please have a look over the code example and the steps given below.

HTML & CSS

We have 4 elements in the HTML file (div, input, label, and button). The div element with a class of container is just a wrapper for the rest of the elements.

The innerText for the button element is “Check”.
The input element is of type checkbox and it has a label of “I like Javascript”. It is unchecked by default and we are going to check it with the help of javascript.
We have done some basic styling using CSS and added the link to our style.css stylesheet inside the head element.

We have also included our javascript file script.js with a script tag at the bottom.

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="style.css">
  <title>Document</title>
</head>

<body>

  <div class="container">
    <button>Check</button>
    <div>
      <input type="checkbox" id="coding" value="javascript">
      <label for="coding">I like Javascript</label>
    </div>
  </div>

  <script src="script.js"></script>
</body>

</html>

.container {
    width: 400px;
    margin: auto;
    display: flex;
    flex-direction: column;
}

button, input  {
  padding: 5px 10px;
  margin-bottom: 20px;
}

Javascript

We have selected the input element and the button element using the document.querySelector() method and stored them in checkbox and btn variables respectively.

We have attached the click event listener to the button element.
In the event handler function, we are using the checked property of the input element and setting it to true. This will change the status of checkbox from unchecked to checked.

let checkbox = document.querySelector("input[type='checkbox']");
let btn = document.querySelector("button");

btn.addEventListener("click", () => {
  checkbox.checked = true
});

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