如何只允许使用JavaScript的字母数字字符

问题描述：

一直在使用JavaScript，我想要做的只是允许传递字段中的某些字符 - az，AZ和0-9。

Been playing around with JavaScript, and what Im trying to do is only allow certain characters in the pass word field - a-z, A-Z and 0-9.

<form action="http://www.cknuckles.com/cgi/echo.cgi" method="get" name="logOn">
  User Name:<br />
  <input type="text" name="userName" size="25" /><br />
  Password:<br />
  <input type="password" name="pw" size="25" /><br />
  <input type="submit" value="Log In" onClick="validate()"/> 
</form>

以上是我的HTML，下面是我尝试用来验证它的JavaScript - 但它不是工作 - 任何线索。

Above is my HTML, and Below is my JavaScript I tried to use to validate it - but it doesnt work - any clues.

<script language="javascript">
   document.logOn.onsubmit=validate;

   function validate(){

var name=document.logOn.pw.value;
    if(!name = "[a-zA-Z0-9]"){              
alert("Your Password Cant Have Any Funky Things In It - Play It Straight!");
    return false;
}               

    return true;
}
</script>

但这不起作用。我仍然可以将字符添加为*和[和{等。

But This isnt working. I can still put chars in like "*" and "[" and "{" etc.

任何想法？

答

你需要让你的条件测试一个正则表达式，而不是一个字符串：

You need to make your condition test a regexp, not a string:

if(!/^[a-zA-Z0-9]+$/.test(name)){ ...

含义：

^ - 行首

[a-zA-Z0-9] + - 一个或多个字符/数字

$ - 行尾

^ -- start of line
[a-zA-Z0-9]+ -- one or more characters/numbers
$ -- end of line

或者您可以搜索反之，即任何不接受的字符：

or you could search for the inverse of that, which is "any non-accepted character":

if(/[^a-zA-Z0-9]/.test(name)){

如何只允许使用JavaScript的字母数字字符

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