[英]Javascript throwing TypeError, document.getElementById when passed PHP variable
I'm trying to write a function that will dynamically display a form (inside a div, of which there will be several instances, thus the weird "id" name) when you click a button. 我正在尝试编写一个函数,当您单击按钮时,该函数将动态显示表单(在div中,其中会有多个实例,因此会有奇怪的“ id”名称)。 Then, it should POST to a separate PHP file. 然后,它应该发布到单独的PHP文件。 Here's the code I have so far: 这是我到目前为止的代码:
function add_comment_url($table, $id) {
$html = '<div id="comment' . $id . '" name="comment_box" style="display: none">
<form action="cgi-bin/add_comment.php" method="post">
<textarea id="comment" name="comment"></textarea>
<input type="hidden" name="id" value="' . $id . '">
<input type="hidden" name="table" value="' . $table . '">
<input type="submit" name="submit" value="Submit Comment">
</form></div>
<input type="button" value="Add Comment" onclick="showComment();">
<script>
var id= ' . json_encode($id) . ';
showComment(id);
</script>';
return($html);
}
The "Add Comment" button shows up fine, but I can't get the to display, and the Firefox console shows a "TypeError: div is null" error when I click on the button. “添加评论”按钮显示正常,但我无法显示,并且当我单击该按钮时,Firefox控制台显示“ TypeError:div is null”错误。
I'm guessing I screwed up the JS variable assignment, but I'm at a loss as to how to fix it. 我猜想我搞砸了JS变量分配,但是我对如何解决这个问题不知所措。 Any thoughts? 有什么想法吗?
EDIT - Final code 编辑-最终代码
I figured out what I did wrong... I was defining the var
when I didn't need to! 我发现我做错了什么...我在不需要时定义了var
! Here's the new function, which works: 这是新功能,可以正常工作:
function add_comment_url($table, $id) {
$html = '<div id="comment' . $id . '" name="comment_box" style="display: none">
<form action="cgi-bin/add_comment.php" method="post">
<textarea id="comment" name="comment"></textarea>
<input type="hidden" name="id" value="' . $id . '">
<input type="hidden" name="table" value="' . $table . '">
<input type="submit" name="submit" value="Submit Comment">
</form></div>
<input type="button" value="Add Comment" onclick="showComment(' . $id . ');">';
return($html);
} }
You can't use <?php
inside PHP strings. 您不能在PHP字符串中使用<?php
。 You should use string concatenation or interpolation: 您应该使用字符串串联或插值:
function add_comment_url($table, $id) {
$html = '<div id="comment' . $id . '" name="comment_box" style="display: none">
<form action="cgi-bin/add_comment.php" method="post">
<textarea id="comment" name="comment"></textarea>
<input type="hidden" name="id" value="' . $id . '">
<input type="hidden" name="table" value="' . $table . '">
<input type="submit" name="submit" value="Submit Comment">
</form></div>
<input type="button" value="Add Comment" onclick="showComment();">
<script>
function showComment() {
var id= ' . json_encode($id) . ';
div = document.getElementById(\'comment\' + id);
div.style.display = "block";}</script>';
return($html);
}
Are you repeating this function definition for every comment block? 您是否为每个注释块重复此函数定义? I would recommend just defining showComment()
once, and make it take the commentID
as an argument. 我建议只定义一次showComment()
,并使其以commentID
作为参数。
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