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Created August 28, 2019 17:07
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General Update Pattern, III
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.block
license: gpl-3.0
Raw
README.md

By adding transitions, we can more easily follow the elements as they are entered, updated and exited. Separate transitions are defined for each of the three states. To avoid repeating transition timing parameters for the enter, update, and exit selections, a top-level transition t sets the duration, and then subsequent transitions use selection.transition, passing in t to inherit timing:

var t = d3.transition()
    .duration(750);

Want to read more? Try these tutorials:

See the D3 wiki for even more resources.

Previous: Key Functions

forked from mbostock's block: General Update Pattern, III

Raw
index.html
<!DOCTYPE html>
<meta charset="utf-8">
<style>
text {
font: bold 48px monospace;
}
.enter {
fill: green;
}
.update {
fill: #333;
}
.exit {
fill: brown;
}
</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
var alphabet = "abcdefghijklmnopqrstuvwxyz".split("");
var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height"),
g = svg.append("g").attr("transform", "translate(32," + (height / 2) + ")");
function update(data) {
var t = d3.transition()
.duration(750);
// JOIN new data with old elements.
var text = g.selectAll("text")
.data(data, function(d) { return d; });
// EXIT old elements not present in new data.
text.exit() // Does this only get called for the number of elements that actually exit?
.attr("class", "exit")
.transition(t)
.attr("y", 60)
.style("fill-opacity", 1e-6)
.remove();
// UPDATE old elements present in new data.
text.attr("class", "update")
//.attr("y", 0) // Not sure why this is here. It looks uneeded
//.style("fill-opacity", 1) // This also looks uneeded
.transition(t)
.attr("x", function(d, i) { return i * 32; });
// ENTER new elements present in new data.
text.enter().append("text")
.attr("class", "enter")
.attr("dy", ".35em")
.attr("x", function(d, i) { return i * 32; })
.attr("y", -60)
.style("fill-opacity", 1e-6)
.text(function(d) { return d; })
.transition(t)
.attr("y", 0)
.style("fill-opacity", 1);
}
// The initial display.
update(alphabet);
// Grab a random sample of letters from the alphabet, in alphabetical order.
d3.interval(function() {
update(d3.shuffle(alphabet)
.slice(0, Math.floor(Math.random() * 26))
.sort());
}, 1500);
</script>
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