在Javascript里面回应PHP？ [英] Echo PHP inside Javascript?

问题描述

为什么这不起作用？

<?php 

mysqli_select_db($connect,"dev");
$response = "Select response from revbut where session='$u'";
$rquery  =  mysqli_query($connect,$response);

$responseanswer = mysqli_fetch_array($rquery);
$re  = $responseanswer['response'];
?>

<script type="text/javascript">
<?php echo $re; ?>
</script>

$ re 里面的JavaScript没有得到回应。但如果我把它放在上面的PHP函数中，它就会得到回应。

$re inside JavaScript is not getting echoed. But if I place it inside the above PHP function, it is getting echoed.

编辑 - 但是为什么这不起作用？

EDIT - BUT THEN WHY IS THIS NOT WORKING?

if(<?php echo $re; ?>){
    document.getElementById('hide').style.display = "none";
}

如果我将隐藏功能置于if之外 - 它正在工作。

if I PLACE the hide function outside the if - it is working.

推荐答案

它得到回应，但你不会在你的页面上看到任何内容，因为文本将写在Javascript标签内，这是浏览器不显示。查看您的页面来源以确认文本确实存在。

It get's echoed, but you won't see anything on your page as the text will be written within the Javascript-tag which is not displayed by the browser. Look at your page source to verify that the text is really there.

编辑

尝试

if(<?php echo json_encode($re); ?>){
    document.getElementById('hide').style.display = "none"; 
}

这将确保您的PHP字符串将转换为适当的Javascript类型 - 如果是字符串，它将确保字符串包含在中并正确转义。

This will ensure that your PHP string will be converted into the appropriate Javascript type - in case of strings it'll ensure that the string is enclosed in " and is escaped properly.

再次编辑

当您执行以下操作时

<script type="text/javascript"> 
if(<?php echo $re; ?>){
    document.getElementById('hide').style.display = "none"; } 
</script>

这是写给HTML的内容页面（然后由浏览器解释）

this is what is written to the HTML page (that's then interpreted by the browser)

<script type="text/javascript"> 
if(whatever is in the $re vairable){
    document.getElementById('hide').style.display = "none"; } 
</script>

但这甚至不是有效的Javascript。你想要的是

But this is not even valid Javascript. What you want is

<script type="text/javascript"> 
if("whatever is in the $re vairable"){
    document.getElementById('hide').style.display = "none"; } 
</script>

注意确保整个东西是有效的Javascript，并且浏览器的Javascript引擎将 $ re 的内容解释为Javascript字符串。对 json_encode（）的调用正是这样 - 它将PHP变量转换为适当的Javascript变量。

Note the " which ensures that the whole thing is valid Javascript and that the contents of $re will be interpreted as an Javascript string by the Browser's Javascript engine. The call to json_encode() does exactly this - it transforms PHP variables into the appropriate Javascript variables.

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