JavaScript that uses a Regex to split a string, ensuring balanced parenthesis and balanced quotes.

Example.js

var input = "a, b, (c, d), (e, (f, g), h), 'i, j, (k, l), m', 'n, \"o, 'p', q\", r'";
var result = SplitBalanced(input, ",");
// Results: 
    ["a", 
     " b", 
     " (c, d)", 
     " (e, (f, g), h)", 
     " 'i, j, (k, l), m'", 
     " 'n \"o, 'p', q\", r'"];

SplitBalanced.js

function SplitBalanced(input, split, open, close, toggle, escape) {
    // Build the pattern from params with defaults:
    var pattern = "([\\s\\S]*?)(e)?(?:(o)|(c)|(t)|(sp)|$)"
                    .replace("sp", split)
                    .replace("o", open || "[\\(\\{\\[]")
                    .replace("c", close || "[\\)\\}\\]]")
                    .replace("t", toggle || "['\"]")
                    .replace("e", escape || "[\\\\]");
    var r = new RegExp(pattern, "gi");
    var stack = [];
    var buffer = [];
    var results = [];
    input.replace(r, function($0,$1,$e,$o,$c,$t,$s,i){
        if ($e) { // Escape
            buffer.push($1, $s || $o || $c || $t);
            return;
        }
        else if ($o) // Open
            stack.push($o);
        else if ($c) // Close
            stack.pop();
        else if ($t) { // Toggle
            if (stack[stack.length-1] !== $t)
                stack.push($t);
            else
                stack.pop();
        }
        else { // Split (if no stack) or EOF
            if ($s ? !stack.length : !$1) {
               buffer.push($1);
               results.push(buffer.join(""));
               buffer = [];
               return;
            }
        }
        buffer.push($0);
    });
    return results;
}