chunk/split a string in Javascript without breaking words

Here's some brute force code that will do it:

function splitIntoLines(input, len) {
    var i;
    var output = [];
    var lineSoFar = "";
    var temp;
    var words = input.split(' ');
    for (i = 0; i < words.length;) {
        // check if adding this word would exceed the len
        temp = addWordOntoLine(lineSoFar, words[i]);
        if (temp.length > len) {
            if (lineSoFar.length == 0) {
                lineSoFar = temp;     // force to put at least one word in each line
                i++;                  // skip past this word now
            }
            output.push(lineSoFar);   // put line into output
            lineSoFar = "";           // init back to empty
        } else {
            lineSoFar = temp;         // take the new word
            i++;                      // skip past this word now
        }
    }
    if (lineSoFar.length > 0) {
        output.push(lineSoFar);
    }
    return(output);
}

function addWordOntoLine(line, word) {
    if (line.length != 0) {
        line += " ";
    }
    return(line += word);
}

If this routine encounters a single word longer than the desired line length, it will put it on a line by itself and will not break it up.

You can play with it here: http://jsfiddle.net/jfriend00/fbaLe/

This builds on @steve's answer but will split the string respecting word break so that the string is never longer than the specified length. This works more like a normal word wrap.

function chunkString(s, len)
{
    var curr = len, prev = 0;

    output = [];

    while(s[curr]) {
      if(s[curr++] == ' ') {
        output.push(s.substring(prev,curr));
        prev = curr;
        curr += len;
      }
      else
      {
        var currReverse = curr;
        do {
            if(s.substring(currReverse - 1, currReverse) == ' ')
            {
                output.push(s.substring(prev,currReverse));
                prev = currReverse;
                curr = currReverse + len;
                break;
            }
            currReverse--;
        } while(currReverse > prev)
      }
    }
    output.push(s.substr(prev)); 
    return output;
}