Align text within d3 svg

Question

I am having trouble with a simple task in d3 as I am new to the library.

Using the gradient example, I've inserted a linear gradient into the footer div element:

    #footer {
      position: absolute;
      z-index: 10;
      bottom: 10px;
      left: 50%;
      width: 300px;
      margin-left: -150px;
      height: 20px;
      border: 2px solid black;
      background: rgba(12, 12, 12, 0.8);
      color: #eee;
    }

var svg = d3.select("footer")
    .append("svg:svg")
    .attr("width", 300)//canvasWidth)
    .attr("height", 20);

svg.append("rect")
    .attr("width", 300)
    .attr("height", 20)
    .style("fill", "url(#linear-gradient)");

var defs = svg.append("defs");


var linearGradient = defs.append("linearGradient")
    .attr("id", "linear-gradient");

linearGradient.append("stop")
.attr("offset", "0%")
.attr("stop-color", "#ffa474"); 

linearGradient.append("stop")
    .attr("offset", "100%")
    .attr("stop-color", "#8b0000");

how would one insert text "a" and "b" on either side of the gradient so that the text is within the bar and aligned to the left and right sides, while appearing above the color? I have tried adding text in the div element but this only "pushes" aside the gradient bar

Answer 1

You can position your text elements using text-anchor. For the first text, set text-anchor to start. For the last one, set text-anchor to end:

svg.append("text")
    .attr("text-anchor", "start")
    .attr("x", 4)//padding of 4px
    .attr("y", 14)
    .text("a");

svg.append("text")
    .attr("text-anchor", "end")
    .attr("x", 296)//padding of 4px
    .attr("y", 14)
    .text("b");

Here is a demo:

var svg = d3.select("#footer")
    .append("svg:svg")
    .attr("width", 300)//canvasWidth)
    .attr("height", 20);
		
var defs = svg.append("defs");

var linearGradient = defs.append("linearGradient")
    .attr("id", "linear-gradient");

linearGradient.append("stop")
.attr("offset", "0%")
.attr("stop-color", "#ffa474"); 

linearGradient.append("stop")
    .attr("offset", "100%")
    .attr("stop-color", "#8b0000");

svg.append("rect")
    .attr("width", 300)
    .attr("height", 20)
    .style("fill", "url(#linear-gradient)");
		
svg.append("text")
	.attr("text-anchor", "start")
	.attr("x", 4)
	.attr("y", 14)
	.text("a");
	
svg.append("text")
	.attr("text-anchor", "end")
	.attr("x", 296)
	.attr("y", 14)
	.text("b");

#footer {
      position: absolute;
      z-index: 10;
      bottom: 10px;
      left: 50%;
      width: 300px;
      margin-left: -150px;
      height: 20px;
      border: 2px solid black;
      background: rgba(12, 12, 12, 0.8);
      color: #eee;
    }

<script src="https://d3js.org/d3.v4.min.js"></script>
<div id="footer"></div>