我如何通过按键事件代码知道该字符是否刚刚输入 <textarea> 是小写还是大写？

Question

I'm trying to capture the character just entered into a . But I can only get which key is pressed via key event like keydown or keyup, not knowing if it's lower case or upper case.

For example, when I input A or a, the event key codes for keydown are all 65. I thought of using val() to get the string in the and get the last character of it. But that is too slow and memory consuming, since I want to record every keyboard event while the user is typing.

So is there a way I can simply get the last entered character? Thanks in advance!

Answer 1

Try this:

 var p = $('#log')[0]; $("#textarea").on("keypress", function(e) { p.textContent = ''; var k = e.keyCode || e.which; var character = String.fromCharCode(k); if (!isNaN(character * 1)) { p.textContent += 'character is numeric'; } else { if (character == character.toUpperCase()) { p.textContent += 'UPPER case true'; } if (character == character.toLowerCase()) { p.textContent += 'lower case true'; } } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <textarea id="textarea"></textarea> <p id="log"></p> 

Answer 2

I see what you mean about the shiftKey

var myObj = $('#myTextarea');

function isLetter(char){
  if ((char.toLowerCase() !== char) || (char.toUpperCase() !== char)) {
    return true;
  } 
  return;
}

myObj.keypress(function( event ){
  var text = myObj.val();
  var char = text.charAt(text.length-1);
  if (!event.shiftKey && isLetter(char)) {
    if (char == char.toUpperCase()) {
      console.log('Upper');
    }
    if (char == char.toLowerCase()) {
      console.log('Lower');
    }
  }
});

Answer 3

try:

<textarea id="area1"></textarea>

---

window.onload = function () {
    document.getElementById("area1").onkeypress = function(event){

        var code = event.which;

        if ((code >= 65) && (code <= 90)) {
            alert('Upper');
        }
        else if ((code >= 97) && (code <= 122)) {
            alert('Lower');
        }           

    }
}