function appendMultiText(container, str, posX, posY, width, fontsize, fontfamily){
   
   if( arguments.length < 6){
    fontsize = 14;
   }  
   
   if( arguments.length < 7){
    fontfamily = "simsun, arial";
   }
   
   //获取分割后的字符串
   var strs = splitByLine(str,width,fontsize);
   
   var mulText = container.append("text")
    .attr("x",posX)
    .attr("y",posY)
    .style("font-size",fontsize)
    .style("font-family",fontfamily);
    
   mulText.selectAll("tspan")
    .data(strs)
    .enter()
    .append("tspan")
    .attr("x",mulText.attr("x"))
    .attr("dy","1em")
    .text(function(d){
     return d;
    });
    
   return mulText;
   
   function splitByLine(str,max,fontsize){
    var curLen = 0;
    var result = [];
    var start = 0, end = 0;
    for(var i=0;i<str.length;i++){
     var code = str.charCodeAt(i);
     var pixelLen = code > 255 ? fontsize : fontsize/2;
     curLen += pixelLen;
     if(curLen > max){
      end = i;
      result.push(str.substring(start,end));
      start = i;
      curLen = pixelLen;
     }
     if( i === str.length - 1 ){
      end = i;
      result.push(str.substring(start,end+1));
     }
    }
    return result;
   }
}

<script src="multext.js" charset="utf-8"></script> 

<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script> 

appendMultiText( 
  container,     //文本的容器，可以是<svg>或<g>  
  str,        //字符串 
  posX,        //文本的x坐标 
  posY,        //文本的y坐标 
  width,       //每一行的宽度，单位为像素 
  fontsize,      //文字的大小（可省略），默认为 14 
  fontfamily     //文字的字体（可省略），默认为 simsun, arial 
) 

var width = 300; 
var height = 300; 
 
var svg = d3.select("body") 
      .append("svg") 
      .attr("width",width) 
      .attr("height",height); 

var str = "青青子衿，悠悠我心，但为君故，沉吟至今。";       
             
appendMultiText(svg,str,30,100,120,20,"simsun"); 

var str = "青青子衿，悠悠我心，但为君故，沉吟至今。";       
             
var multext = appendMultiText(svg,str,30,100,120,20,"simsun"); 
         
multext.attr("transform","rotate(-20)"); 

var g = svg.append("g"); 
             
var multext = appendMultiText(g,str,30,100,120);