Change javascript onclick event to jquery click and still pass parameters

Question

I think I may be missing something or haven't grasped a fundamental of jQuery. I have searched for hours but yet to find an answer to my question.

I've got an old website that I'm upgrading to use jQuery and many of the links call a JavaScript onClick call that passes multiple parameters, as per the example below:

<a href="#" onclick="displayData('Book Title', 'ISBN', 'dateOfPublishing', 'Price');">View Details</a>

The problem is that I've updated the old displayData function with various jQuery code and the displayData function is within the

$(document).ready(function() { 
});

code, and this seems to prevent the function displayData being called using the onClick as it says object expected. I've moved the displayData function out from the $(document).ready() but by doing so, this has prevented references to other functions within the $(document).ready() code being referenced.

A cut down example of what I have is below:

<script>
  $(document).ready(function() {
    function displayData(title, isbn, dt, price) {
      // there's a call to jQuery AJAX here
        $.ajax({
            type: "POST",
            contentType: "application/json; charset=utf-8",
            url: "WebServices/BookService.asmx/GetBookReviews",
            data: "{isbn: '" + isbn + "'}",
            dataType: "json",
            success: function(msg) {
                DisplayReviews(msg.d);
            }
        });
      return false;
    }

    function DisplayReviews(data) {
       // data normally formatted here and passed to formattedData variable
       var formattedData = FormatData(data);
       $('#reviewScreen').html(formattedData);
    }

    function FormatData(data) {
      // function reformats data... code removed for space..
      return data;
    }


  });
</script>


<table>
  <tr><td><a href="#" class="reviewLink" onclick="displayData('Book Title', '1234141HABJA1', '2010-01-12', '$15.99');">View Reviews</a></td><td>Book Title</td></tr>
  <tr><td><a href="#" class="reviewLink" onclick="displayData('Book TItle 2', '516AHGN1515', '1999-05-08', '$25.00');">View Reviews</a></td><td>Book Title 2</td></tr>
</table>

What I'd like to do is to be able to remove the onclick="displayData();" within the link and instead us a jQuery click reference, something like

$('a.reviewLink').click(function() {
  displayData(parameters go here....);
});

I just don't know how I'd pass the parameters to the function from the link as they would not longer be in the HTML onclick attribute.

If I continue to use the onclick attribute in the link, and move the displayData(params) out of the $(document).ready() code block, it works fine, but the moment I try and reference any of the other functions within the $(document).ready() code block I get the dreaded object expected error with the other functions such as DisplayReviews(param).

I don't know if this makes any sense.... sorry if it's confusing, I'm not the worlds best programmer and don't know all the terminology necessarily, so have tried as best I can to explain. I hope you can help.

Many thanks

Solution 1

The init code should go into the .ready(), not your library functions, those can be defined in a seperate .js file.

<script src="yourFunctions.js"></script>
<script>
    $(document).ready(function(){

         $('a.reviewLink').click(function() {
             displayData(parameters go here....); // in yourFunctions.js
         });

    });
</script>

An alternative to passing inline parameters without using inline javascript, is to use HTML5's 'data-' attribute on tags. You can use it in xhtml, html etc as well and it just works.

html:

<div data-name="Jack" data-lastname="black">My name is</div>

jquery:

 $('div').click(function(){
      alert($(this).attr('data-name') + ' ' + $(this).attr('data-lastname'));
 });

Note: You HAVE to use either jQuery's .attr() or native .getAttribute() method to retreive 'data-' values.

I use 'data-' myself all the time.

Solution 2

As pointed out by Skilldrick, displayData doesn't need to be defined inside your document ready wrapper (and probably shouldn't be).

You are correct in wanting to use the jQuery click event assignment rather than onClick - it makes your code easier to read, and is required by the principle of Unobtrusive Javascript.

As for those parameters that you want to pass, there are a few ways to go about the task. If you are not concerned with XHTML compliance, you could simply put some custom attributes on your link and then access them from your script. For example:

<a href="#" booktitle="Book Title" isbn="ISBN" pubdate="Publish Date" price="Price">View Details</a>

And then in your click event:

$('a.reviewLink').click(function() {
  var booktitle = $(this).attr('booktitle');
  var isbn = $(this).attr('isbn');
  var pubdate = $(this).attr('pubdate');
  var price = $(this).attr('price');
  displayData(booktitle, isbn, pubdate, price);
});

I'm sure someone on here will decry that method as the darkest evil, but it has worked well for me in the past. Alternatively, you could follow each link with a hidden set of data, like so:

<a href="#">View Details</a>
<ul class="book-data">
   <li class="book-title">Book Title</li>
   <li class="book-isbn">ISBN</li>
   <li class="book-pubdate">Publish Date</li>
   <li class="book-price">Price</li>
</ul>

Create a CSS rule to hide the data list: .book-data { display: none; }, and then in your click event:

$('a.reviewLink').click(function() {
  var $bookData = $(this).next('.book-data');
  var booktitle = $bookData.children('.book-title').text();
  var isbn = $bookData.children('.book-isbn').text();
  var pubdate = $bookData.children('.book-pubdate').text();
  var price = $bookData.children('.book-price').text();
  displayData(booktitle, isbn, pubdate, price);
});

There are lots of ways to accomplish your task, but those are the two that spring most quickly to mind.