[Solved]-Fit Text into SVG Element (Using D3/JS)-d3.js

I had a similar issue and found a reasonable solution by calculating the width of my box. Secondly, I figured out that on average the character width for my current font is about 8. Next I simply do a substring on the text to be displayed. That seems to work perfectly in most cases.

var rectText = rectangles.append("text")
    .text(function(d) {

        TextBoxLength = timeScale(dateFormat.parse(d.endTime)) - timeScale(dateFormat.parse(d.startTime));
        return d.task.substring(0, Math.floor(TextBoxLength / 8));
    })
    .attr("x", function(d) {
        return (timeScale(dateFormat.parse(d.endTime)) - timeScale(dateFormat.parse(d.startTime))) / 2 + timeScale(dateFormat.parse(d.startTime)) + theSidePad;
    })
    .attr("y", function(d, i) {
        return d.position * theGap + 14 + theTopPad;
    })
    .attr("font-size", 12)
    .attr("text-anchor", "middle")
    .attr("text-height", theBarHeight)
    .attr("fill", "#000000");

Another approach, when trying to fit a straight line of text into an svg element, could use the strategy found in http://bl.ocks.org/mbostock/1846692:

node.append("text")
  .text(function(d) { return d.name; })
  .style("font-size", function(d) { return Math.min(2 * d.r, (2 * d.r - 8) / this.getComputedTextLength() * 24) + "px"; })
  .attr("dy", ".35em");

This technique might come in handy. It works with the current svg spec and without foreignObject element http://bl.ocks.org/mbostock/7555321

To make it work with the animations just enclose in a group element and animate that one instead. http://jsfiddle.net/MJJEc/

body = d3.select('body')
svg = body.append('svg')
                    .attr('height', 600)
                    .attr('width', 200);
    var g = svg.append('g').attr("transform" ,"scale(0)");
    rect = g.append('rect')
                    .attr('width', 150)
                    .attr('height', 100)
                    .attr('x', 40)
                    .attr('y', 100)
                    .style('fill', 'none')
                    .attr('stroke', 'black')
    text = g.append('foreignObject')
                    .attr('x', 50)
                    .attr('y', 130)
                    .attr('width', 150)
                    .attr('height', 100)
                    .append("xhtml:body")
                    .html('<div style="width: 150px;">This is some information about whatever</div>')

    g.transition().duration(500).attr("transform" ,"scale(1)");