D3 v4 - force layout

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge"/>
<title>D3 v4 - force layout</title>
<style>
html, body, #graph {
    width: 900px;
    height: 500px;
}
</style>
</head>

<body>
<div id="graph"></div>    
    
    
    
<script src="//cdnjs.cloudflare.com/ajax/libs/d3/4.1.1/d3.min.js"></script>    
<script>
!(function(){
    "use strict"

var width,height
    var chartWidth, chartHeight
    var margin
    var svg = d3.select("#graph").append("svg")
    var chartLayer = svg.append("g").classed("chartLayer", true)
    
    main()
    
    function main() {
        var range = 100
        var data = {
            nodes:d3.range(0, range).map(function(d){ return {label: "l"+d ,r:~~d3.randomUniform(8, 28)()}}),
            links:d3.range(0, range).map(function(){ return {source:~~d3.randomUniform(range)(), target:~~d3.randomUniform(range)()} })        
        }
        
        setSize(data)
        drawChart(data)    
    }
    
    function setSize(data) {
        width = document.querySelector("#graph").clientWidth
        height = document.querySelector("#graph").clientHeight
    
        margin = {top:0, left:0, bottom:0, right:0 }
        
        
        chartWidth = width - (margin.left+margin.right)
        chartHeight = height - (margin.top+margin.bottom)
        
        svg.attr("width", width).attr("height", height)
        
        
        chartLayer
            .attr("width", chartWidth)
            .attr("height", chartHeight)
            .attr("transform", "translate("+[margin.left, margin.top]+")")
            
            
    }
    
    function drawChart(data) {
        
        var simulation = d3.forceSimulation()
            .force("link", d3.forceLink().id(function(d) { return d.index }))
            .force("collide",d3.forceCollide( function(d){return d.r + 8 }).iterations(16) )
            .force("charge", d3.forceManyBody())
            .force("center", d3.forceCenter(chartWidth / 2, chartWidth / 2))
            .force("y", d3.forceY(0))
            .force("x", d3.forceX(0))
    
        var link = svg.append("g")
            .attr("class", "links")
            .selectAll("line")
            .data(data.links)
            .enter()
            .append("line")
            .attr("stroke", "black")
        
        var node = svg.append("g")
            .attr("class", "nodes")
            .selectAll("circle")
            .data(data.nodes)
            .enter().append("circle")
            .attr("r", function(d){  return d.r })
            .call(d3.drag()
                .on("start", dragstarted)
                .on("drag", dragged)
                .on("end", dragended));    
        
        
        var ticked = function() {
            link
                .attr("x1", function(d) { return d.source.x; })
                .attr("y1", function(d) { return d.source.y; })
                .attr("x2", function(d) { return d.target.x; })
                .attr("y2", function(d) { return d.target.y; });
    
            node
                .attr("cx", function(d) { return d.x; })
                .attr("cy", function(d) { return d.y; });
        }  
        
        simulation
            .nodes(data.nodes)
            .on("tick", ticked);
    
        simulation.force("link")
            .links(data.links);    
        
        
        
        function dragstarted(d) {
            if (!d3.event.active) simulation.alphaTarget(0.3).restart();
            d.fx = d.x;
            d.fy = d.y;
        }
        
        function dragged(d) {
            d.fx = d3.event.x;
            d.fy = d3.event.y;
        }
        
        function dragended(d) {
            if (!d3.event.active) simulation.alphaTarget(0);
            d.fx = null;
            d.fy = null;
        } 
                
    }
}());
</script>    
</body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/4.1.1/d3.min.js