block with text

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
    var wide = 150;     		  var high = 150
    var texX = wide/4 - 20;   var texY = high/2 + 10
        
    var svg = d3.select("body")
    	.append("svg")
      	.attr("width", 1500)
      	.attr("height", 500)

svg.append('rect')
    	.attr('width', wide)
    	.attr('height', high)
    	.attr('x', 10)
    	.attr('y', 10) 
    	.style('fill', 'red')
    
    svg.append('rect')
    	.attr('width', wide)
    	.attr('height', high)
    	.attr('x', wide+30)
    	.attr('y', 10) 
    	.style('fill', 'blue')

svg.append("text")
      .text("Red box!")
      .attr("x", texX)
      .attr("y", texY)
      .attr("font-size", 25)
      .attr("font-family", "monospace")
    
   texX = texX+wide+20
   
    svg.append("text")
      .text("Blue box!")
      .attr("x", texX)
      .attr("y", texY)
      .attr("font-size", 25)
      .attr("font-family", "monospace")

</script>
</body>

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