Convention-based event handlers

HTML

<button id="panel-button-2">panel-2-button</button>
<div id="content-inner-panel-2">content-inner-panel-2</div>

<button id="panel-button-2_medium">panel-button-2_medium</button>
<div id="content-inner-panel-2_medium">content-inner-panel-2_medium</div>

<button id="panel-button-2_large">panel-button-2_large</button>
<div id="content-inner-panel-2_large">content-inner-panel-2_large</div>

<button id="panel-button-3">panel-3-button</button>
<div id="content-inner-panel-3">content-inner-panel-3</div>

<button id="panel-button-3_medium">panel-button-3_medium</button>
<div id="content-inner-panel-3_medium">content-inner-panel-3_medium</div>

<button id="panel-button-3_large">panel-button-3_large</button>
<div id="content-inner-panel-3_large">content-inner-panel-3_large</div>

JavaScript

$('button').click(function() {
    var identifier = this.id.substring(this.id.lastIndexOf("-"));
    $('#content-inner-panel' + identifier).css("color", "red");
});