Text-wrapping routine.

It might be useful to expose this as d3.svg.textWrap?

function wrap(text, width) {
  text.each(function() {
    var text = d3.select(this),
        words = text.text().split(/\s+/).reverse(),
        word,
        line = [],
        lineNumber = 0,
        lineHeight = 1.1, // ems
        y = text.attr("y"),
        dy = parseFloat(text.attr("dy")),
        tspan = text.text(null).append("tspan").attr("x", 0).attr("y", y).attr("dy", dy + "em");
    while (word = words.pop()) {
      line.push(word);
      tspan.text(line.join(" "));
      if (tspan.node().getComputedTextLength() > width) {
        line.pop();
        tspan.text(line.join(" "));
        line = [word];
        tspan = text.append("tspan").attr("x", 0).attr("y", y).attr("dy", ++lineNumber * lineHeight + dy + "em").text(word);
      }
    }
  });
}

Live example: http://bl.ocks.org/mbostock/7555321

[bunkat]

If this does get added, there is a bug that I noticed when I used this recently. If the first word is wider than the specified width, a blank line is produced instead. Just making sure you don’t pop when there is only one word in the line solves the problem.

if(line.length > 1) line.pop();

[emiguevara]

A follow up on bunkat’s comment, indeed first words that are longer than the provided width generate an empty tspan . An extra condition must be added to prevent this, from:

if (tspan.node().getComputedTextLength() > width) { ... }

to:

if (tspan.node().getComputedTextLength() > width && line.length > 1) {...}