d3.js fit scale to rgb() range of blue

Question

Trying to fill rect colours on a bar chart by a scale,

  var x1 = d3.scaleTime()
    .domain([parseTime('00:00'), d3.max(data, function(d) {
      return d.value
    })])
    .range([2, 256]);

like this,

  .style('fill', function(d) {
          return "'rgb(0,0," + x1(d.value) + ")'"
        })

Trying to range over the colour blue on the scale d.value

I'm getting black at the moment, presumable a default colour.

Thanks

Answer 1

You can simplify this, d3 scales can interpolate between colors, so you could use code such as :

 var x1 = d3.scaleLinear()
    .domain([0,100]])
    .range(["#000000","#0000ff"]);

You could also use:

 var x1 = d3.scaleLinear()
    .domain([0,100]])
    .range(["black","blue"]);

And then use the scale to color to the rectangles directly:

.style('fill', function(d) { 
          return x1(d.value);
        })

Also, yes, black is the default color. For sake of demonstration in the snippet, I'm using a linear rather than date scale:

var svg = d3.select("body")
  .append("svg")
  .attr("width",500)
  .attr("height",200);

var x1 = d3.scaleLinear()
  .domain([0,100])
  .range(["#000000","#0000ff"]);

var x2 = d3.scaleLinear()
  .domain([0,100])
  .range(["orange","steelblue"]);
        
var rects = svg.selectAll(null)
  .data(d3.range(100))
  .enter()
  .append("rect")
  .attr("fill",function(d) { return x1(d); })
  .attr("width",10)
  .attr("height",10)
  .attr("y",function(d) { return Math.floor(d/10) * 12; })
  .attr("x",function(d) { return d % 10 * 12; })

var rects = svg.selectAll("null")
  .data(d3.range(100))
  .enter()
  .append("rect")
  .attr("fill",function(d) { return x2(d); })
  .attr("width",10)
  .attr("height",10)
  .attr("y",function(d) { return Math.floor(d/10) * 12; })
  .attr("x",function(d) { return d % 10 * 12 + 130 ; })

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