Scatterplot/Beeswarm/forceSimulation/forceCollide

<!DOCTYPE html>
<meta charset="utf-8">
<p id="g1"></p> 
<head>
	<style>
  	body {
      font-family: "Helvetica Neue", Helvetica, sans-serif;
      font-size: 14px;
    }
	div.tooltip {
    position: absolute;
    text-align: center;
    /*width: 150px;*/
    height: 28px;
    padding: 2px 5px;
    font: 12px sans-serif;
    background: lightsteelblue;
    border: 0px;
    border-radius: 8px;
    pointer-events: none;
  }
	</style>
	<script src="//d3js.org/d3.v4.min.js"></script>
	
</head>
<body ng-app="app" ng-controller="ctrl">
  
  <div id="chart"></div>
</body>

for (i = 0; i < samples; i++) {
        var date = new Date(+(new Date()) - Math.floor(Math.random()*1000000000));
        
        data.push({
          datetime: date,
          pivot: items[Math.floor(Math.random()*items.length)]
        });
      }
      return data;
		}

// *** Create random data set using above function
    var fullData = randomData(300);

// *** Set up svg
    var margin = { top: 20, right: 20, bottom: 60, left: 60 };
    		width = 960 - margin.left - margin.right,
    		height = 400 - margin.top - margin.bottom;

var tooltip = d3.select("#chart").append("div")
    	.attr("class", "tooltip")
    	.style("opacity", 0);

var x = d3.scaleTime().range([0, width-margin.left]).nice();
    var y = d3.scaleBand().rangeRound([0, height]);
      
    // *** Parse the date / time
    var parseDate = d3.timeParse("%e/%m/%Y");
    var formatDateTime = d3.timeFormat("%e/%m/%Y" );
    var parseTime = d3.timeParse("%H:%M:%S");
    var formatDateTime = d3.timeFormat("%e/%m/%Y %H:%M:%S");

// *** Scale the range of the data
    var earliestDate = d3.min(fullData, function(d) { return d.datetime; });
    var latestDate = d3.max(fullData, function(d) { return d.datetime; });

x.domain([earliestDate, latestDate]);
    y.domain(d3.map(fullData, function(d){return d.pivot;}).keys().sort());
	
    var xAxis = d3.axisBottom(x).tickFormat(d3.timeFormat("%Y-%m-%d"));
    var yAxis = d3.axisLeft(y);
  
		fullData.forEach(function(d) {
      d.idealy = y(d.pivot)+((height/items.length)/2);
    });
     
    var svg = d3.select("#chart").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
    .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var clip = svg.append("defs").append("svg:clipPath")
    .attr("id", "clip")
    .append("svg:rect")
    .attr("width", width )
    .attr("height", height )
    .attr("x", 0) 
    .attr("y", 0);

var scatter = svg.append("g")
    .attr("id", "scatterplot")
    .attr("clip-path", "url(#clip)");

var colour = d3.scaleOrdinal()
    .domain(d3.map(fullData, function(d){return d.pivot;}).keys())
    .range(d3.schemeCategory10);

// x axis
    svg.append("g")
      .attr("class", "x axis")
      .attr('id', "axis--x")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis)
      .selectAll("text")	
      .style("text-anchor", "end")
      .attr("dx", "-.8em")
      .attr("dy", ".15em")
      .attr("transform", "rotate(-65)");

svg.append("text")
         .style("text-anchor", "end")
            .attr("x", width)
            .attr("y", height - 8)
         .text("Date");

// y axis
    svg.append("g")
      .attr("class", "y axis")
      .attr('id', "axis--y")
      .call(yAxis);
    
    svg.append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", "1em")
      .style("text-anchor", "end")
      .text("Time");
  
		var simulation = d3.forceSimulation(fullData)
      .force("x", d3.forceX(function(d) { return x(d.datetime); }))
      .force("y", d3.forceY(function(d) { return d.idealy; }))
      .force("collide", d3.forceCollide(4)
             	.strength(1)
      				.iterations(2))
      .stop();

console.log(fullData[0]);
  for (var i = 0; i < 120; ++i) simulation.tick();

scatter.selectAll(".dot")
      .data(fullData)
      .enter().append("circle")
      .attr("class", "dot")
      .attr("r", 4)
      .attr("cx", function(d) { return d.x })
      .attr("cy", function(d) { return d.y; })
      .attr("opacity", 0.7)
      .style("fill", function(d) { return colour(d.pivot); })
    	.on("mouseover", function(d) {
             tooltip.transition()
               .duration(200)
               .style("opacity", .9);
             tooltip.html(formatDateTime(d.datetime) + "<br/>" + d.pivot)
               .style("left", (d3.event.pageX) + "px")
               .style("top", (d3.event.pageY - 28) + "px");
          		
           })
           .on("mouseout", function(d) {
             tooltip.transition()
               .duration(500)
               .style("opacity", 0);
           });

</script>

https://d3js.org/d3.v4.min.js