To make a new line (<br />) on the text every 10 chars

gistfile1.js

function binSearch(text, searchLen) {
     var left = 0, right = text.length;
     var breakPos = left, lastBreakPos = right;
     while (Math.abs(lastBreakPos - breakPos) > 1) {
        lastBreakPos = breakPos;
        breakPos = Math.floor((left+right)/2);
        if (searchLen < getTextWidth(text.substring(0, breakPos)))
           right = breakPos - 1;
        else
           left = breakPos + 1;
     }
     return Math.min(breakPos, lastBreakPos);
  }

  function getTextWidth(text) {
     var ea = document.createElement("span");
     ea.innerHTML = text;
     document.body.appendChild(ea);
     var len = ea.offsetWidth;
     document.body.removeChild(ea);
     return len;
  }

  function linebreak(text, maxLen) {
     var breakPos = 0;
     var out = "";
     var part1 = text, part2 = "";
     if (getTextWidth(part1) > maxLen) {
        while (getTextWidth(part1) > maxLen) {
           var breakPos = binSearch(part1, maxLen);
           part2 = part1.substring(breakPos, part1.length);
           part1 = part1.substring(0, breakPos);
           out += part1 + "<br/>";
           part1 = part2;
        }
        return out + part2;
     }
     else
        return text;
  }
  
  // excample:
  linebreak(el.innerHTML, 150);