jQuery Sparkline - Overriden tooltip
https://groups.google.com/d/topic/jquery-sparkline/s-XjpA9QMWo/discussion
HTML
<script src="http://omnipotent.net/jquery.sparkline/2.1/jquery.sparkline.js"></script>
<p>
linechart appears here: <span id="line"> </span>
</p>
JavaScript
// jsfiddle configured to load jQuery Sparkline 2.1
// http://omnipotent.net/jquery.sparkline/
// Values to render
var values = [5];
// Draw a sparkline for the #sparkline element
$('#line').sparkline(values, {
type: "line",
// Make the tooltip say "NA" for values of -1
tooltipFormat: "{{y:val}}",
tooltipValueLookups: {"val": {"-1": "N/A"}}
});