如何验证输入文本允许第一和第二位数字仅为字母

Question

I need to validate a input text, the first 2 digits only letters after adding a hyphen and finally 5 numerical digits.

format example: aa-12345

now i have

<asp:TextBox ID="txtCodigoTopografo" onkeydown="test(this)"   runat="server"></asp:TextBox>

function test(e) {
        console.log(e);

        switch (e.value.length) {

            case 0:
                if (e.value)
                e.value = e.value.replace(/[^a-z]/gi, '');
                break;

            case 1:
                e.value = e.value.replace(/[^a-z]/gi, ''); 
                break;
            case 2:
               e.value = e.value.replace(/[^0-9]/gi, '');
                break;
            case 3:
                e.value = e.value.replace(/[^0-9]/gi, '');
              
                break;
        }


       
        
       
    }

Answer 1

Your current method is trying to replace stuff with regex. Instead, use regex to verify your input string is in the correct format.

This regex assumes the letters must be lower case. You can change [az] to [Az] if you allow upper or lower case.

 function test() { var textboxContent = document.getElementById("input").value; var passed = /^[az]{2}-\\d{5}$/.test(textboxContent); if (passed) { document.getElementById("result").textContent = "Passed!"; } else { document.getElementById("result").textContent = "Failed!"; } }

 <input type="text" id="input" placeholder="Type here!" oninput="test()" /> <p id="result"></p>

An explanation of the regex:

^     Match the start of the input. Used so that you don't match part way along the input
[a-z] Match a lowercase letter...
{2}   ...2 times (you could do "[a-z][a-z]" instead)
-     Match hyphen
\d    Match a digit...
{5}   ...5 times (you could do "\d\d\d\d\d" instead)
$     Match the end of the input. Used so that you don't match part way along the input