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javascript - javascript更改键盘键的值

问题描述

我有一个文本字段只包含字母，如果我按下（a）我得到（b）并且如果我按下（b）得到（c）......等等，如果我按下（z）得到警报（“没有后面的字母")

    <input type="number" id="example" onkeypress="return numbersKey(event)">
    <p id="demo"></p>
    <input type="text" id="example2" onkeypress="return lettersOnly(event)">
    <script>
        var myinput = document.getElementById('example'),
            myp = document.getElementById('demo');
        function numbersKey(evt) { 
      
            // Only ASCII charactar in that range allowed 

            var ASCIICode = event.keyCode;

            if (ASCIICode > 31 && (ASCIICode < 48 || ASCIICode > 57))

                return false;

            return true;
            
        };
            
        }
        function lettersOnly() 
        {
            // Only ASCII character in that range allowed
            var charCode = event.keyCode;

            if ((charCode > 64 && charCode < 91) || (charCode > 96 && charCode < 123) || charCode == 8){

                return String.fromCharCode(event.keyCode + 1);
            }    
            else
                return false;
        }

标签： javascripthtml

解决方案

粘贴此完整代码并运行一次即可查看。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input type="text" id="example2" onkeypress="lettersOnly(event)">
    <p id="demo"></p>
</body>
<script>
    function lettersOnly(event) {
        var charCode = event.keyCode;
        if ((charCode > 64 && charCode < 91) || (charCode > 96 && charCode < 123) || charCode == 8){
            if(charCode == 90 || charCode == 122){
                document.getElementById('demo').innerHTML = "There's no letter after";
            }
            else{
                document.getElementById('demo').innerHTML = String.fromCharCode(event.keyCode + 1);
            }

        }    
        else{
            document.getElementById('demo').innerHTML = "Not Letter";
        }
    }

</script>
</html>

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