format.js

function format(text, width) {
  var formatted = '';
  var words = text.split(' ');
  var line_length = 0;
  
  words.map(function(value, index){ 
    // The first word shouldn't have a space before it, and the length check shouldn't
    // add any extra to the line count
    if( index == 0){
      addition = 0;
    }
    else {
      addition = 1;
    }
    
    // If adding the word won't push us over the edge...
    if(line_length + value.length + addition <= width){

      // If this is the first word of the first line, don't include a space
      if(addition == 1) {
        // Append the word to the string
        formatted += ' ' + value;
      }
      else {
        // Append the word to the string
        formatted += value;
      }
      
      // And update the current length of the line
      line_length += value.length + addition;
    }
    else {
      // Add a new line character and append the word to the new line
      formatted += '\n';
      
      // Reset char count
      line_length = 0;
      
      // Append the word to the string
      formatted += value;
      
      // And update the current length of the line
      line_length += value.length;
    }
  });
  
  return formatted;
}