如何将按钮的PHP变量onclick发送给javascript函数作为参数

Question

I am using codeigniter 3. Below is the code of the view page, where data inside the $row->poll_question; is coming from the database. Thus, the different values coming inside this variable are echoed on a page called voting.php. And just beside this variable, there is a button called View Poll. Now, on clicking this button I want to pass the data of this php variable to javascript section. And simply alert and check in javascript. Please help. I have pasted the code I tried.

voting.php

<h3 class="val" id="val" style="color:rgb(158, 158, 158);font-family: 
arial;margin-top: 2%;" ><?php echo $row->poll_question; ?></h3>
</td>

<td>

<a class="btn btn-lg btn-primary view_button" id="view_button" 
 style="margin-left: 18%;padding:10%;border-radius: 10px;" 
 onclick="fetch_val(<?php echo $row->poll_question ?>)">View Poll</a>

Javascript

function fetch_val(val)
{
     alert(val);
}

Answer 1

You have forgot to add quote on '<?php echo $row->poll_question ?>' . Check updated code below

<h3 class="val" id="val" style="color:rgb(158, 158, 158);font-family: 
arial;margin-top: 2%;" ><?php echo $row->poll_question; ?></h3>
</td>

<td>

<a class="btn btn-lg btn-primary view_button" id="view_button" 
 style="margin-left: 18%;padding:10%;border-radius: 10px;" 
 onclick="fetch_val('<?php echo $row->poll_question ?>')">View Poll</a>

Answer 2

I don't recommend the redundant storage of the string.

You already have the value in your id 'ed <h3> tag. Just use that.

Further advice move all stylings to an external stylesheet and use a javascript listener on your #view_button .

You could stay with an inline function call:

<h3 class="val" id="val"><?php echo $row->poll_question; ?></h3>

<a class="btn btn-lg btn-primary view_button" id="view_button" 
   onclick="fetch_val(document.getElementById('val').innerHTML);">View Poll</a>

Or trigger fetch_val() via a listener written in your javascript (this is the cleaner / more professional way):

document.getElementById('view_button').onclick = function() {
    alert(document.getElementById('val').innerHTML);
}

About writing a pure javascript onclick handler: https://stackoverflow.com/a/17633164/2943403

Assigning a custom function to an event: https://stackoverflow.com/a/24665785/2943403

Using either of my above techniques will remove the possibility of quoting issues caused by questions like What is your mother's maiden name? .