D3 Appending Text to a SVG Rectangle

A rect can’t contain a text element. Instead transform a g element with the location of text and rectangle, then append both the rectangle and the text to it:

var bar = chart.selectAll("g")
    .data(data)
  .enter().append("g")
    .attr("transform", function(d, i) { return "translate(0," + i * barHeight + ")"; });

bar.append("rect")
    .attr("width", x)
    .attr("height", barHeight - 1);

bar.append("text")
    .attr("x", function(d) { return x(d) - 3; })
    .attr("y", barHeight / 2)
    .attr("dy", ".35em")
    .text(function(d) { return d; });

http://bl.ocks.org/mbostock/7341714

Multi-line labels are also a little tricky, you might want to check out this wrap function.