Question

这是我创建注册页面的尝试，但是在for循环之后，后续的任何内容都没有执行，我不知道为什么？以下是javascript代码和表单

<script type='text/javascript'>
myArray = ['username','email','password','password2'];
reply = ['User Name','Email','Password','Password Again'];
message = "Please Type you're ";
start = "<font color = red size='-1'>";
end = "</font>";
test = 10;
obj = validate();
alert (obj);
function validate(){

for (var i=0; i<=myArray.length; i++) {
               if (document.getElementById("in"+myArray[i]).value == "")
               {
                   document.getElementById(myArray[i]).innerHTML = start+message+reply[i]+end;
                   test = 30;
               }
                }
alert ("test");
}

<form action="echo.php" method="post" name="register" onsubmit="return validate();">
<table>
    <tr>
      <td width="185"><font size="2">First Name</font></td>
      <td width="499">
        <input id = "infirst_name" name="first_name" type="text" /><div id="first_name"></div></td>
    </tr>
    <tr>
      <td><font size="2">Last Name</font></td>
      <td><input id = "inlast_name" name="last_name" type="text" /><div id="last_name"></font></div></td>
    </tr>
    <tr>
      <td><font size="2">Username*</font></td>
      <td>
        <input id = "inusername" name="username" type="text" /><div id="username"></div></td>
    </tr>
    <tr>
      <td><font size="2">Email*</font></td>
      <td><input id = "inemail" name="email" type="text" /><div id="email"></div></td>
    </tr>
    <tr>
      <td><font size="2">Password*</font></td>
      <td><input id = "inpassword" name="password" type="password" /><div id="password"></div></td>
    </tr>
    <tr>
      <td><font size="2">Repeat Password*</font></td>
      <td>
        <input id = "inpassword2" name="password2" type="password" /><div id="password2"></div></td>
    </tr>
    <tr>
    <tr>
      <td><font size="2">I have read and Agree to the Terms and Conditions</font></td>
      <td>
        <input id = "incheckme" name="checkme" type="checkbox" /><div id="checkme"></div></td>
    </tr>
    <tr>
      <td><input type="submit" value="Register" /></td>
      <td>&nbsp;</td>
    </tr>
  </table>
</form>

Answer 1

尝试修复循环：

for (var i=0; i < myArray.length; i++) {

如果遇到未捕获的错误，JavaScript将停止执行任何操作。在你的情况下，似乎你已经循环了最后一个元素（并尝试在未定义的对象上设置innerHTML）。

Answer 2

最有可能的原因是你遍历数组的末尾，但引用它就像那里有东西一样。

Answer 3

请参阅JS控制台输出：也许它说您有错误。 i超出myArray长度：将循环条件从“i＆lt; =”更改为“i＆lt;”你会没事的。

为什么JavaScript代码在for循环后停止执行

3 个答案: