JS: Changing this function to handle a link click - php

Question

Following the example here Very Simple jQuery and PHP Ajax Request – Ready to use code
I've been successful in creating a drop down list that passes the value to an external PHP script and returns the HTML output back to a "div" on the same page and it works great.
What I want to do now is post values when I click on link instead of building a drop down list. So ...if I created this link:
Route Number 2
I want "2" passed to that external PHP script and the content changed on the " div " as it currently works with the dropdown. I don't know how to change the javascript to handle this or what "foo.php" really needs to be.
Here's the current javascript from that example:
<script type="text/javascript">
$(document).ready(function() {
$('#route_number').click(function() {
routenumber = $('#route_number').val();
$.post('api.php', { route_number : routenumber }, function(res) {
$("#mainlayer").html(res);
});
});
});
</script>
And here's what the dropdown portion of the HTML looks like:
<select name="route_number" id="route_number">
<option value="notchosen">Please Choose A Route</option>
<option value="2">Riverfront</option>
<option value="11">Magazine</option>
<option value="16">Claiborne</option>
</select>
<div id="mainlayer">
</div>
So, to be clear, instead of a dropdown that passes values, I want to create links that accomplish the same result.
Thanks in advance,
dan -

Answer 1

Create a class, capture its (meaning whatever link you clicked on) value, then post.
<a class="RouteNumber" href="foo.php?route_number=2">Route Number 2</a>
$(function(){
$('a.RouteNumber').on('click',function(event){
// prevent the browser's default action for clicking on a link
event.preventDefault();
// break href attribute into array, then parse desired value as int
var routenumber = $(this).attr('href').split('='),
rtnum = parseInt(routenumber[1]);
$.post('api.php',{route_number:rtnum},function(res){
$("#mainlayer").html(res);
});
});
});
If you don't need to parse the integer out of it (if a string is good enough), you don't need that second variable. You can just use routenumber[1] in the post data.
Just a heads up, I modified the jQuery to use the .on() syntax. .click() is shorthand for it, but I like using .on() just because it allows for less potential codewriting if you want to do more (like mouseenter/mouseleave, for example) because you can combine them into a single codeset.

Answer 2

I had hoped simply fixing #LifeInTheGrey's example would've sufficed, but there are some things I would've done differently that probably need some explaining.
Your HTML could look something like this:
<a class="route" href="foo.php?route_number=2" data-route="2">Route Number 2</a>
The JavaScript would look something like this:
$(function() {
var fill_div_with_response = function(res) {
$("#mainlayer").html(res);
};
var handle_error = function(res) {
alert('something went wrong!');
};
$(document.body).on('click', '.route', function(event) {
// prevent the browser's default action for clicking on a link
event.preventDefault();
// grab route number from data attribute
var route = $(this).data('route');
// make that post request
$.post('api.php', {route_number: route})
// handle the response
.done(fill_div_with_response)
// handle errors
.fail(handle_error);
});
});
The example uses delegated events. They're cheap to initialize and consume the least amount of memory.
The example handles errors. Most answers to questions like these neglect that. errors happen. Always. Make people aware of that. Surely throwing an alert() is not the thing you want to be doing, but it's still better than simply ignoring errors completely.
The example uses Deferreds (Promises) rather than callbacks, as this usually makes code much cleaner.
We're defining the callbacks fill_div_with_response() and handle_error() at the root closure to prevent redefining them on the next click. There's no need to feed the garbage collector.
The data attribute poses the optimal alternative to <option value="123"> in the way that it prevents you from having to parse the href attribute to extract that number from a string.

Answer 3

since you want to make a menu, I would modify your markup
<ul name="route_number" id="route_number">
<li value="2">Riverfront</li>
<li value="11">Magazine</li>
<li value="16">Claiborne</li>
</ul>
then simply process that list:
$('#route_number').find('li').click(function () {
var routenumber = $(this).attr('value');
$.post('api.php', {
route_number: routenumber
}, function (res) {
$("#mainlayer").html(res);
});
});
EDIT1: As an improvement (as you seem to be pretty new to this stuff) you could use the data with altered markup as such:
<ul name="route_number" id="route_number">
<li data-routenumber="2">Riverfront</li>
<li data-routenumber="11">Magazine</li>
<li data-routenumber="16">Claiborne</li>
</ul>
Then the code would be:
$('#route_number').find('li').click(function () {// add click event manager to each li
var routenumber = $(this).data('routenumber');// get routenumber of clicked
$.post('api.php', {
route_number: routenumber
}, function (res) {
$("#mainlayer").html(res);
});
});
Alternate code using .on() form
$('#route_number').on('click, 'li', function () {//click event manager for ul/li
var routenumber = $(this).data('routenumber');// get routenumber of clicked
$.post('api.php', {
route_number: routenumber
}, function (res) {
$("#mainlayer").html(res);
});
});
Note that this last form binds to the #route_number element so you could add more menu options during processing and they would still work. This is also better than attachment to the document as it is a more focused approach to the event attachment.

Answer 4

My understanding of your question is that the functionality you have is fine, and you just need to change the look to a piece of text from a dropdown. If so, good news! You can keep (almost) the same JavaScript.
Right now, your JavaScript is getting the value of your select box, sending it via AJAX, and using the returned value. The only change you need is to get the 'value' of the text clicked.
You don't want to use a link, since that's designed to take the user someplace. Instead you can use a span and format it to look like a link, or even a button if you want that kind of look.
You will also need to change $('#route_number').val();, probably to something passed by the click event. For example:
<span id="route1" class="routeSpan" onclick="sendVal(1)">Route 1 Name</span>
<span id="route2" class="routeSpan" onclick="sendVal(2)">Route 2 Name</span>
And your JavaScript:
function sendVal(routeVal) {
$.post('api.php',{route_number:routeVal},function(res){
$("#mainlayer").html(res);
});
}