Detect 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!

  • Regular Expressions for the Rest of Us

    Sooner or later you’ll run across a regular expression. With their cryptic syntax, confusing documentation and massive learning curve, most developers settle for copying and pasting them from StackOverflow and hoping they work. But what if you could decode regular expressions and harness their power? In…

  • 7 Essential JavaScript Functions

    I remember the early days of JavaScript where you needed a simple function for just about everything because the browser vendors implemented features differently, and not just edge features, basic features, like addEventListener and attachEvent.  Times have changed but there are still a few functions each developer should…

  • Multiple Backgrounds with CSS

    Anyone that’s been in the web development industry for 5+ years knows that there are certain features that we should have had several years ago. One of those features is the HTML5 placeholder; we used JavaScript shims for a decade before placeholder came…

  • Prevent Page Zooming in Mobile Browsers

    Ever since I got my iPhone, I’ve been more agreeable in going places that my fiancee wants to go. It’s not because I have any interest in checking out women’s shoes, looking at flowers, or that type of stuff — it’s because my iPhone lets…



Source link
case studies

See More Case Studies

Contact us

Partner with Us for Comprehensive IT

We’re happy to answer any questions you may have and help you determine which of our services best fit your needs.

Your benefits:
What happens next?
1

We Schedule a call at your convenience 

2

We do a discovery and consulting meting 

3

We prepare a proposal 

Schedule a Free Consultation