lineWrap.js

function lineWrap(str) {    
  // Split by lines
  return str.split(/\r|\n|\r\n/g).reduce(function(prev, piece) {
    
    var parts = [];
    
    // Wrap line
    while (piece.length) {
      var match = piece.match(/^.{1,80}(?:\s|$)/),
          matchlen;
      
      if (!match) {
        match = [piece.substr(0, 80)];
      }
      
      if (matchlen = match[0].length) {
        parts.push(match[0]);
        piece = piece.substr(matchlen);
      }
    };
    
    return prev.concat(parts);
    
  }, []).join('\r\n');
}