Animated Sparkline using SVG Path and d3.js

<html>
	<head>
		<title>Animated Sparkline using SVG Path and d3.js</title>
		<script src="https://cdn.jsdelivr.net/npm/d3@2.10.3/d3.v2.js"></script>
		<style>
			/* tell the SVG path to be a thin blue line without any area fill */
			path {
				stroke: steelblue;
				stroke-width: 1;
				fill: none;
			}
		</style>
	</head>
	<body>

// create a simple data array that we'll plot with a line (this array represents only the Y values, X will just be the index location)
		var data = [3, 6, 2, 7, 5, 2, 1, 3, 8, 9, 2, 5, 9, 3, 6, 3, 6, 2, 7, 5, 2, 1, 3, 8, 9, 2, 5, 9, 2, 7, 5, 2, 1, 3, 8, 9, 2, 5, 9, 3, 6, 2, 7, 5, 2, 1, 3, 8, 9, 2, 9];

// X scale will fit values from 0-10 within pixels 0-100
		var x = d3.scale.linear().domain([0, 48]).range([-5, 300]); // starting point is -5 so the first value doesn't show and slides off the edge as part of the transition
		// Y scale will fit values from 0-10 within pixels 0-100
		var y = d3.scale.linear().domain([0, 10]).range([0, 30]);

// create a line object that represents the SVN line we're creating
		var line = d3.svg.line()
			// assign the X function to plot our line as we wish
			.x(function(d,i) { 
				// verbose logging to show what's actually being done
				//console.log('Plotting X value for data point: ' + d + ' using index: ' + i + ' to be at: ' + x(i) + ' using our xScale.');
				// return the X coordinate where we want to plot this datapoint
				return x(i); 
			})
			.y(function(d) { 
				// verbose logging to show what's actually being done
				//console.log('Plotting Y value for data point: ' + d + ' to be at: ' + y(d) + " using our yScale.");
				// return the Y coordinate where we want to plot this datapoint
				return y(d); 
			})
			.interpolate("basis")
	
			// display the line by appending an svg:path element with the data line we created above
			graph.append("svg:path").attr("d", line(data));
			// or it can be done like this
			//graph.selectAll("path").data([data]).enter().append("svg:path").attr("d", line);
			
			
			function redrawWithAnimation() {
				// update with animation
				graph.selectAll("path")
					.data([data]) // set the new data
					.attr("transform", "translate(" + x(1) + ")") // set the transform to the right by x(1) pixels (6 for the scale we've set) to hide the new value
					.attr("d", line) // apply the new data values ... but the new value is hidden at this point off the right of the canvas
					.transition() // start a transition to bring the new value into view
					.ease("linear")
					.duration(1000) // for this demo we want a continual slide so set this to the same as the setInterval amount below
					.attr("transform", "translate(" + x(0) + ")"); // animate a slide to the left back to x(0) pixels to reveal the new value
					
					/* thanks to 'barrym' for examples of transform: https://gist.github.com/1137131 */
			}
			
			function redrawWithoutAnimation() {
				// static update without animation
				graph.selectAll("path")
					.data([data]) // set the new data
					.attr("d", line); // apply the new data values
			}
			
			setInterval(function() {
			   var v = data.shift(); // remove the first element of the array
			   data.push(v); // add a new element to the array (we're just taking the number we just shifted off the front and appending to the end)
			   redrawWithAnimation();
			   //redrawWithoutAnimation();
			}, 1000);
		
	</script>

</body>
</html>

Modified http://mbostock.github.com/d3/d3.v2.js to a secure url

https://mbostock.github.com/d3/d3.v2.js