本文介绍了如何使用Javascript在HTML文本框上设置最小和最大字符长度的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我只是GCSE级别，我的代码中需要一个文本框，只有4个字符。我已经使它最多4，但我需要它至少4。我也让它只接受数字。我在学校没有使用HTML 5.
I am only GCSE level and I need a text box in my code to only have 4 characters. I have made it a max of 4 but I need it to have a minimum of 4 aswell. I also made it only accept numbers. I am not using HTML 5 at my school.
这是我的全部代码：
<head> <title>Exam entry</title> <script language="javascript" type="text/javascript"> function validateForm() { var result = true; var msg=""; if (document.ExamEntry.name.value=="") { msg+="You must enter your name \n"; document.ExamEntry.name.focus(); document.getElementById('name').style.color="red"; result = false; } if (document.ExamEntry.subject.value=="") { msg+="You must enter the subject. \n"; document.ExamEntry.subject.focus(); document.getElementById('subject').style.color="red"; result = false; } if (document.ExamEntry.ExamNumber.value=="") { msg+="You must enter your exam number. \n"; document.ExamEntry.ExamNumber.focus(); document.getElementById('ExamNumber').style.color="red"; result = false; } if(document.ExamEntry.ExamNoLen.value.length <4) { msg+="Your eaxm nuber must be 4 digits long. \n"; document.ExamEntry.ExamNumber.focus(); document.getElementById('ExamNumber').style.color="red"; result = false; } checkInput(elem){ if(elem.value.length != 4){ alert("This value needs to be 4 characters long!"); elem.value = ""; // Reset the textbox } else{ alert("This value is 4 characters long."); } } if(msg==""){ return result; } { alert(msg) return result; } } </script> </head> <body> <h1>Exam Entry Form</h1> <form name="ExamEntry" method="post" action="success.html"> <table width="50%" border="0"> <tr> <td id="name">Name</td> <td><input type="text" name="name" /></td> </tr> <tr> <td id="subject">Subject</td> <td><input type="text" name="subject" /></td> </tr> <tr> <td id="ExamNumber">Exam Number </td> <td> <input name="ExamNumber" type="text" onkeydown="return ( event.ctrlKey || event.altKey || (47<event.keyCode && event.keyCode<58 && event.shiftKey==false) || (95<event.keyCode && event.keyCode<106) || (event.keyCode==8) || (event.keyCode==9) || (event.keyCode>34 && event.keyCode<40) || (event.keyCode==46) )" maxlength="4" onblur="checkInput(this)" /> </td> </tr> <tr> <td><input type="submit" name="Submit" value="Submit" onClick="return validateForm();" /></td> <td><input type="reset" name="Reset" value="Reset" /></td> </tr> </table> </form> </body>推荐答案
嗯，你的用户不能拥有最小长度需要输入1,2和3个字符才能达到4.（除非你应用某种更先进的输入掩码）。但是当它模糊时你可以检查它是4个字符长。
Well you can't have a minlength because your users are going to need to type 1,2 and 3 characters to get to 4. (Unless you apply some sort of input mask which is more advanced). But you can check that it is 4 characters long when it is blurred..
<input name="ExamNumber" type="text" onblur="checkInput(this)" onkeydown="return ( event.ctrlKey || event.altKey || (47<event.keyCode && event.keyCode<58 && event.shiftKey==false) || (95<event.keyCode && event.keyCode<106) || (event.keyCode==8) || (event.keyCode==9) || (event.keyCode>34 && event.keyCode<40) || (event.keyCode==46) )" maxlength="4" />然后是一个简单的JavaScript函数..
And then a simple JavaScript function..
function checkInput(elem){ if(elem.value.length != 4){ alert("This value needs to be 4 characters long!"); elem.value = ""; // Reset the textbox } else{ alert("This value is 4 characters long."); } }更多推荐
如何使用Javascript在HTML文本框上设置最小和最大字符长度
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