Sunday, June 16, 2024

Detect Caps Lock with JavaScript

Software DevelopmentDetect Caps Lock with JavaScript

Anyone is capable of having their caps lock key on at any given time without realizing so. Users can easily spot unwanted caps lock when typing in most inputs, but when using a password input, the problem isn’t so obvious. That leads to the user’s password being incorrect, which is an annoyance. Ideally developers could let the user know their caps lock key is activated.

To detect if a user has their keyboard’s caps lock turn on, we’ll employ KeyboardEvent‘s getModifierState method:

document.querySelector('input[type=password]').addEventListener('keyup', function (keyboardEvent) {
    const capsLockOn = keyboardEvent.getModifierState('CapsLock');
    if (capsLockOn) {
        // Warn the user that their caps lock is on?
    }
});

I’d never seen getModifierState used before, so I explored the W3C documentation to discover other useful values:

dictionary EventModifierInit : UIEventInit {
  boolean ctrlKey = false;
  boolean shiftKey = false;
  boolean altKey = false;
  boolean metaKey = false;

  boolean modifierAltGraph = false;
  boolean modifierCapsLock = false;
  boolean modifierFn = false;
  boolean modifierFnLock = false;
  boolean modifierHyper = false;
  boolean modifierNumLock = false;
  boolean modifierScrollLock = false;
  boolean modifierSuper = false;
  boolean modifierSymbol = false;
  boolean modifierSymbolLock = false;
};

getModifierState provides a wealth of insight as to the user’s keyboard during key-centric events. I wish I had known about getModifier earlier in my career!

Request Metrics real user monitoring
Request Metrics real user monitoring
Request Metrics real user monitoring
  • Responsive Images: The Ultimate Guide

    Responsive Images: The Ultimate Guide

    Chances are that any Web designers using our Ghostlab browser testing app, which allows seamless testing across all devices simultaneously, will have worked with responsive design in some shape or form. And as today’s websites and devices become ever more varied, a plethora of responsive images…

  • CSS Animations Between Media Queries

    CSS Animations Between Media Queries

    CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during…

  • MooTools Zebra Table Plugin

    MooTools Zebra Table Plugin

    I released my first MooTools class over a year ago. It was a really minimalistic approach to zebra tables and a great first class to write. I took some time to update and improve the class. The XHTML You may have as many tables as…

  • Create a Custom “:selected” Pseudo Selector in MooTools

Check out our other content

Check out other tags:

Most Popular Articles