Formats a valid JSON string into a pretty output

PrettyJson.cs

/// <summary>
/// Formats a JSON string by walking through it and examining the contents.
/// </summary>
/// <param name="json">Unformatted JSON string, expects valid JSON with quoted keys and no whitespace.</param>
/// <returns>Formatted JSON string</returns>
/// <remarks>
/// [ { should have line breaks and tabs after them
/// ] } should have line breaks and tabs before them
/// : should have a space after it
/// , should have a line break and tab
/// </remarks>
public static string PrettyJson(this string json) {
	var sbOutput = new StringBuilder();
	var tokens = new char[] {'{','}','[',']',',',':'};
	bool inQuotes = false;
	int level = 0;
	
	Action Blockify = () => {
		var chars = new char[level];

		for (var i = 0; i < level; i++)
			chars[i] = '\t';
			
		sbOutput.AppendLine();
		sbOutput.Append(chars);
	};

	for (var i = 0; i < json.Length; i++) {
		var curChar = json[i];

		// Ignore escaped quotes
		if (curChar == '"' && json[i-1] != '\\')
			inQuotes = !inQuotes;

		// Ignore anything in quotes or that isn't a token
		if (inQuotes || !tokens.Contains(curChar)) {
			sbOutput.Append(curChar); 
			continue;
		}
			
		if (curChar == '{' || curChar == '[' || curChar == ',') {
			if (curChar != ',') level++;
			sbOutput.Append(curChar);
			Blockify();
		}
		else if (curChar == '}' || curChar == ']') {
			level--;			
			Blockify();
			sbOutput.Append(curChar);
		}
		else if (curChar == ':') {
			sbOutput.Append(curChar + " ");
		}
	}

	return sbOutput.ToString();
}

PrettyJson.js

// Formats a well-formed JSON string into a pretty version
String.prototype.prettyJson = function() {
    var json = this,
        output = "",
        tokens = ['{', '}', '[', ']', ',', ':'],
        inQuotes = false,
        level = 0,
        blockify = function() {
            output += '\r\n';

            for (var k = 0; k < level; k++) {
                output += '  ';
            }
        };

    for (var i = 0; i < json.length; i++) {
        var curChar = json.charAt(i);

        // Ignore escaped quotes
        if (curChar === '"' && json.charAt(i - 1) !== '\\') {
            inQuotes = !inQuotes;
        }

        // Ignore anything in quotes or that isn't a token
        if (inQuotes || tokens.indexOf(curChar) === -1) {
            output += curChar;
            continue;
        }

        if (curChar === '{' || curChar === '[' || curChar === ',') {
            if (curChar !== ',') level++;
            output += curChar;
            blockify();
        } else if (curChar === '}' || curChar === ']') {
            level--;
            blockify();
            output += curChar;
        } else if (curChar === ':') {
            output += curChar + " ";
        }
    }

    return output;
};