detect caps lock status on page load (or similar)

问题:

In my research, I've found how to detect capslock when the caps key is pressed. However, I want to know the caps status even in cases when the key is not touched.

example: alert(ui.Keyboard.capslock) // would return true or false;

Thanks!

回答1:

No, you cannot get the state of a keyboard button on page load. You have to analyze a keyCode of a keypress. That is the only way.

回答2:

I've just come up with an alternative which will detect the state of caps lock and store it so that if the caps lock key is pressed a warning can be turned on and off. I'm only coding for chrome 45+ and ie9+ so there may need to be some adjustments for general use if that is your plan.

Here's my html:

<input type="text" id="pwd">
<p id="caps"></p>

And here's the js:

var LOGINPAGE = LOGINPAGE || {};
LOGINPAGE.CAPSdetect = {};
$(function() {
    LOGINPAGE.CAPSdetect.engage();
});

LOGINPAGE.CAPSdetect.isDetected = false;
LOGINPAGE.CAPSdetect.capsOn = false;

LOGINPAGE.CAPSdetect.engage = function() {
    $('#pwd').on('keypress', LOGINPAGE.CAPSdetect.shiftDetect);
    $(window).on('keydown', LOGINPAGE.CAPSdetect.capsDetect);
}

LOGINPAGE.CAPSdetect.shiftDetect = function(event) {
    var caps = $('#caps');
    var which = event.keyCode;
    var shift = event.shiftKey;
    var targ = event.target;
    if ((which >= 65 && which <= 90 && !shift) || (which >= 97 && which <= 122 && shift)) {
        caps.html('CAPS LOCK IS ON').css('color', 'crimson');
        LOGINPAGE.CAPSdetect.isDetected = true;
        LOGINPAGE.CAPSdetect.capsOn = true;
    } else if((which >= 65 && which <= 90 && shift) || (which >= 97 && which <= 122 && !shift)){
        caps.html('');
    }
}

LOGINPAGE.CAPSdetect.capsDetect = function(event) {
    if(event.keyCode === 20 && LOGINPAGE.CAPSdetect.isDetected) {
        LOGINPAGE.CAPSdetect.capsOn = (LOGINPAGE.CAPSdetect.capsOn)? false:true;
        if(LOGINPAGE.CAPSdetect.capsOn) {
            $('#caps').html('CAPS LOCK IS ON');
        } else {
            $('#caps').html('');
        }
    }
}

I'm using namespaces to avoid globals for isDetected and capsOn hence the LOGINPAGE.CAPSdetect. before some functions and variables. See this jsfiddle for no namespacing and to test it out.

回答3:

Try this code:

    <script language="Javascript">
function capLock(e){
 kc = e.keyCode?e.keyCode:e.which;
 sk = e.shiftKey?e.shiftKey:((kc == 16)?true:false);
 if(((kc >= 65 && kc <= 90) && !sk)||((kc >= 97 && kc <= 122) && sk)){
  document.getElementById('divon').style.visibility = 'visible';
   document.getElementById('divoff').style.visibility = 'hidden';
 }else{
  document.getElementById('divon').style.visibility = 'hidden';
   document.getElementById('divoff').style.visibility = 'visible';
}
}
</script>
<input type="text" name="trackcaps" onkeypress="capLock(event)" />
<div id="divon" style="visibility:hidden">Caps Lock is on.</div>
<div id="divoff" style="visibility:hidden">Caps Lock is off.</div>