0

我有一些预制的 javascript，它与来自我的数据库的预设响应的表单交互。单击插入按钮时没有任何反应，chrome 显示错误：未捕获的类型错误：无法读取 null 的属性“selectionStart”

这是javascript/php/html：

 <tr><?php echo tep_draw_form('status', FILENAME_ORDERS, tep_get_all_get_params(array('action')) . 'action=update_order'); ?>
         <td class="main">
            <script language="javascript">  
                  function insereTexto(){  
                     //Paste into textarea
                     var textarea = document.getElementById("txt");  

                     //Text to be inserted  
                     var texto = document.getElementById("txtValor").value;  

                     //beginning of the selection 
                     var sel_start = textarea.selectionStart;              

                     //end of the selection  
                     var sel_end = textarea.selectionEnd;  


                     if (!isNaN(textarea.selectionStart))  
                     //Treatment for Mozilla
                     {  
                        var sel_start = textarea.selectionStart;  
                        var sel_end = textarea.selectionEnd;  

                        mozWrap(textarea, texto, '')  
                        textarea.selectionStart = sel_start + texto.length;  
                        textarea.selectionEnd = sel_end + texto.length;  
                     }     

                     else if (textarea.createTextRange && textarea.caretPos)   
                     {  
                        if (baseHeight != textarea.caretPos.boundingHeight)   
                        {  
                           textarea.focus();  
                           storeCaret(textarea);  
                        }        
                        var caret_pos = textarea.caretPos;  
                        caret_pos.text = caret_pos.texto.charAt(caret_pos.texto.length - 1) == ' ' ? caret_pos.text + text + ' ' : caret_pos.text + text;  

                     }  
                     else //For those who can not enter, insert at the end of it (ie. ..)
                     {  
                        textarea.value = textarea.value + texto;  
                     }        
                  }  

                  /* 
                  This function opens the text of two strings and inserts the text at the cursor position well after he joins novamento text but the text entered
This wonderful feature only works in Mozilla ... IE does not have the properties SelectionStart, textLength ...
                  */  
                  function mozWrap(txtarea, open, close)  
                  {  
                     var selLength = txtarea.textLength;  
                     var selStart = txtarea.selectionStart;  
                     var selEnd = txtarea.selectionEnd;  
                     var scrollTop = txtarea.scrollTop;  

                     if (selEnd == 1 || selEnd == 2)   
                     {  
                        selEnd = selLength;  
                     }  
                     //S1 has the text from the beginning to the cursor position 
                     var s1 = (txtarea.value).substring(0,selStart);  

                     //S2 has the selected text 
                     var s2 = (txtarea.value).substring(selStart, selEnd)  

                     //S3 has all the selected text  
                     var s3 = (txtarea.value).substring(selEnd, selLength);  

                     //Places the text in the textarea. Uses the string that was in the beginning, in the middle of the input string, then the selection string then the
                     //closing and finally what's left after the selection
                     txtarea.value = s1 + open + s2 + close + s3;           
                     txtarea.selectionStart = selEnd + open.length + close.length;  
                     txtarea.selectionEnd = txtarea.selectionStart;  
                     txtarea.focus();  
                     txtarea.scrollTop = scrollTop;  
                     return;  
                  }  
                  /* 
                  Insert at Caret position. Code from 
                   [url]http://www.faqts.com/knowledge_base/view.phtml/aid/1052/fid/130[/url] 
                  */  
                  function storeCaret(textEl)  
                  {  
                        if (textEl.createTextRange)  
                        {  
                           textEl.caretPos = document.selection.createRange().duplicate();  
                        }  
                  }  

                </script>  

                                <select id="txtValor" /> 
                                <option value="">Select Text</option>
                                <option value="<?php echo $order->customer['name']; ?>">Customer Name</option>
                                <option value="<?php echo STORE_NAME_ADDRESS; ?>">signature</option>
                                <option value="<?php echo STORE_NAME; ?>">Store Name</option>
                                <option value="<?php echo $_SERVER['SERVER_NAME']; ?>">Site</option>
                                <option value="<?php echo STORE_OWNER; ?>">Store Owner</option>
                                <option value="<?php echo STORE_OWNER_EMAIL_ADDRESS; ?>">Email the Store</option>
                                <?php
                                $get_premades_query = tep_db_query("select * from orders_premade_comments order by id");
                                while($result = mysql_fetch_array($get_premades_query)) {
                                echo '<option value="'.$result["text"].'">'. $result["title"].'</option>';
                                }
                                ?>
                                </select>
                                <input type="button" value="Insert at the cursor position" onclick="insereTexto()"/>  
                                <input type="button" value="Clean" onclick="this.form.elements['comments'].value=''">
                                    <font class="smallText"><a href="premade_comments.php">[Setup]</a></font><br>


        <?php echo tep_draw_textarea_field('comments', 'soft', '80', '10','','id="txt"'); ?></td>
      </tr>

我真的不太了解javascript，php正在调用正确的数据库字段，我可以正确地回显它们。但是我猜测 selectionStart 函数没有被正确使用？

4

2 回答 2

2

消息说：

Cannot read property 'selectionStart' of null

这是正确的：null没有属性，所以它不能有selectionStart.

那么这是null从哪里来的呢？.selectionStart要求textarea：

                 //beginning of the selection 
                 var sel_start = textarea.selectionStart;

并且textarea来自 DOM：

   //Paste into textarea
   var textarea = document.getElementById("txt");

显然，getElementById()电话返回null而不是返回。

您应该检查 HTML 以验证是否有一个id 为txt. 您还可以添加显式检查，以防这种情况只是间歇性发生：

   //Paste into textarea
   var textarea = document.getElementById("txt");
   if (!textarea)
       alert("Och! No txt textarea defined?");

...当它发生时，检查 HTML 源代码以验证发生这种情况的原因。也许您并不总是显示 textarea，也许 ID 发生了变化等。

于 2013-07-04T14:29:12.880 回答
1

这是你的问题

 var textarea = document.getElementById("txt");

未在您的文档中定义

  • 另一个警告：使用不支持的 html 标签

    <font class="smallText"><a href="premade_comments.php">[Setup]</a></font>

    该<font>标签在 HTML 5 中不受支持，在 HTML 4.01 中已弃用

  • 这里有一个提示： 使用 php 简写回声符号来提高代码的可读性。

    这个<?php echo STORE_NAME_ADDRESS; ?>

    与制作多个 echo 语句时相同，<?=STORE_NAME_ADDRESS ?>并且看起来更好

于 2013-07-04T14:29:57.340 回答