index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>timer / fps</title>
<script src="//d3js.org/d3.v4.min.js"></script>
</head>
<body>
<div id="fps">FPS: <span>?</span></div>
</body>
<script>
var w = 960, h = 100;
var svg = d3.select("body")
.append("svg")
.attr("width",w)
.attr("height",h);
var data = d3.range(w).map(function(d,i) {
return {
x1: i,
y1: 0,
x2: i,
y2: Math.trunc(Math.random()*h)
};
});
var lines = svg.selectAll("line").data(data).enter().append("line")
.attr("x1",function(d) {return d.x1; } )
.attr("y1",function(d) {return d.y1; } )
.attr("x2",function(d) {return d.x2; } )
.attr("y2",function(d) {return d.y2; } )
.attr("stroke", "black" )
var fps = d3.select("#fps span");
var t0 = Date.now(), t1;
d3.timer( function() {
data.forEach( function(d) {
d.y2++;
if (d.y2 > h) d.y2 = 0;
})
lines.attr("y2", function(d) {return d.y2;} )
t1 = Date.now();
fps.text( Math.round(1000 / (t1-t0)));
t0 = t1;
});
</script>
</html>