JavaScript onkeydown – How to Use onkeydown Event with JavaScript

We can use the onkeydown event to run a function when a user types something into an input field. To do this we can add a function call to the onkeydown event in the HTML.

<input type="text" />

The onkeydown event is very similar to the onkeyup event, the main difference being that the onkeydown event will fire once a key is pressed, while the onkeyup event will only run once the key is pressed AND released.

This can also be done in jQuery using the keydown() method.

A JavaScript example using the onkeydown event

In this example, we will just have a simple input field with a div below it. When a user enters a key in the input field, we will display what key was pressed below. Here is the HTML setup:

<div id="div1">
  <p>Type any key below</p>
  <input type="text" id="textInput" onkeydown="keyPressed(event)">
  <div id="result"></div>
</div>

We will use the onkeydown event to run the function below. The function will retrieve the key that was pressed and display that below in the results div using the textContent property.

Here is the JavaScript code:

function keyPressed(e){
  var key = e.key;
  document.getElementById("result").textContent = key;
};

The final code and output for this example of using the onkeydown event is below:

Code Output:

Full Code:

<div id="div1">
  <p>Type any key below</p>
  <input type="text" id="textInput" onkeydown="keyPressed(event)">
  <div id="result"></div>
</div>

<script>

function keyPressed(e){
  var key = e.key;
  document.getElementById("result").textContent = key;
};

</script>

Hopefully this article has been useful to help you understand how to use the onkeydown event.