selection.call() method in D3 can aid in code organization and flexibility by eliminating the need to use chained method calls for every operation.
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<script src="../bower_components/underscore/underscore-min.js"></script>
<script src="../ventor/d3.min.js"></script>
<style type="text/css"> body {
padding-top: 50px;
padding-left: 100px; } #chartArea {
width: 400px;
height: 300px;
background-color: #CCC;
} .bar {
display: inline-block;
width: 20px;
height: 75px; /* Gets overriden by D3-assigned height below */
margin-right: 2px;
/* fill: teal; *//* SVG doesn't have background prop, use fill instead*/
z-index: 99;
} .bubble, .center {
display: inline-block;
fill: purple;
fill-opacity: 0.5;
stroke: black;
stroke-weight: 1px;;
z-index: 15;
} .center {
z-index: 10;
} .active {
fill: magenta;
fill-opacity: 0.5;
stroke-width: 3px;
} .axis path, .axis line {
fill: none;
stroke: #000;
stroke-width: 1px;
shape-rendering: crispEdges;
} </style>
</head>
<body>
<button onclick="update()">Update</button>
<section id="chartArea"></section>
<script> function planTrasition(selection, duration, color){ selection
.transition()
.duration(duration)
.style('fill', color)
.attr('cx', function(each_data, index) {
return xScale(each_data.x);
})
.attr('cy', function(each_data) {
return yScale(each_data.y);
})
.attr('r', function(each_data, i) {
return each_data.r;
});
} function stepTransition(selection) { selection.transition()
.duration(600)
.style('fill', "lightblue")
.attr('cx', function(each_data, index) {
return xScale(each_data.x);
})
.transition()
.duration(600)
.attr('cy', function(each_data) {
return yScale(each_data.y);
})
.transition()
.duration(600)
.attr('r', function(each_data, i) {
return each_data.r;
});
} function newData(d){
d.x = Math.round(Math.random() * 100);
d.y = Math.round(Math.random() * 100);
d.r = Math.round(5 + Math.random() * 10);
} function update(){ //Only the data which x < 50 will get update
svg.selectAll('circle')
.filter(function(d) {
return d.x < 50;
})
.each( newData)
.call(stepTransition); svg.selectAll('circle')
.filter(function(d) {
return d.x >= 50;
})
.each( newData)
.call(planTrasition, 2000, "red");
} var dataset = _.map(_.range(30), function(num) {
return {
x: Math.round(Math.random() * 100),
y: Math.round(Math.random() * 100),
r: Math.round(5 + Math.random() * 10)
};
}), //reandom generate 15 data from 1 to 50
margin = {top: 20, right: 20, bottom: 40, left: 40},
w = 400 - margin.left - margin.right,
h = 300 - margin.top - margin.bottom; var svg = d3.select('#chartArea').append('svg')
.attr('width', w + margin.left + margin.right)
.attr('height', h + margin.top + margin.bottom)
.append('g') //The last step is to add a G element which is a graphics container in SBG.
.attr('transform', 'translate(' + margin.left + ', ' + margin.top + ')'); //Then offset that graphic element by our left and top margins. var yScale = d3.scale.linear()
.domain([0, d3.max(dataset, function(d) {
return d.y; //tell the max function just need to care about y prop
})])
.range([h, 0]); var yAxis = d3.svg.axis()
.scale(yScale)
.orient('left')
.ticks(10)
.innerTickSize(10)
.outerTickSize(10)
.tickPadding(10);
svg.append('g')
.attr('class', 'y axis')
.attr('transform', 'translate(0,0)')
.call(yAxis); var xScale = d3.scale.linear()
.domain([0, 100])
.range([0, w]); var xAxis = d3.svg.axis()
.scale(xScale)
.orient('bottom')
.ticks(10)
.innerTickSize(6)
.outerTickSize(12)
.tickPadding(12); svg.append('g')
.attr('class', 'x axis')
.attr('transform', 'translate(0, ' + h + ')')
.call(xAxis); svg.selectAll('circle')
.data(dataset)
.enter()
.append('circle')// svg doesn't have div, use rect instead
.attr('class', "bubble")
.attr('cx', function(each_data, index) {
return xScale(each_data.x);
})
.attr('cy', function(each_data) {
return yScale(each_data.y);
})
.attr('r', function(each_data, i) {
return each_data.r;
})
.on('mouseover', function() {
d3.select(this).classed('active', true)
})
.on('mouseleave', function() {
d3.select(this).classed('active', false)
})
.on('mousedown', function(d) {
var p_cx = d.x, p_cy = d.y, p_r = d.r;
d3.select(this).transition().duration(500).attr('r', d.r * 1.5);
svg.append('circle')
.attr('class', "center")
.attr('cx', function() {
return xScale(p_cx);
})
.attr('cy', function() {
return yScale(p_cy);
})
.attr('r', function() {
return p_r / 4;
})
.style('fill', 'red');
})
.on('mouseup', function(d) { d3.select(this).transition().duration(250).delay(100).attr('r', d.r)
});
</script>
</body>
</html>
![[D3] 13. Cleaner D3 code with selection.call()](https://image.shishitao.com:8440/aHR0cHM6Ly9iYnNtYXguaWthZmFuLmNvbS9zdGF0aWMvTDNCeWIzaDVMMmgwZEhCekwybHRZV2RsY3pBdVkyNWliRzluY3k1amIyMHZZbXh2WnpJd01UVXZNelkwTWpReEx6SXdNVFV3Tmk4d05USXlNamd3TWpJek9EazRNVGt1Y0c1bi5qcGc%3D.jpg?w=700&webp=1 "[D3] 13. Cleaner D3 code with selection.call()")