basic JSON prettify

simplePrettyJson.js

function simplePrettyJson (str) {
    var stack = [], // collect all tokens
        word = [],  // accumulator to build tokens of more than one char, like an object's keys. 
                    // Not strictly needed but could be useful if we ever allow callbacks
        ws = '',
        tab = '    ', // 3 spaces are standard and 2 are trendy, but 4 are readable
        depth = 0,
        inquotes = false,
        curr, next, prev;
    
    for (var ii = 0, l = str.length; ii < l; ii++) {
        ws = '\n';
        prev = curr;
        curr = str.charAt(ii);
        next = str.charAt(ii + 1);
        if (curr == '"' && prev != '\\') {
            if (!inquotes) {
                inquotes = true;
                stack.push(curr)
            } else {
                stack.push(word.join(''), curr)
                word = [];
                inquotes = false;
            }
        } else if (!inquotes) {
            switch (curr) {
                case '{' :
                    ++depth;
                    stack.push(curr)
                    for (var i = 0; i < depth; i++)
                        ws += tab;
                    stack.push(ws)
                break;
                case '[' :
                    ++depth;
                    stack.push(curr)
                    if (next != ']') { // we want to keep an empty array on the same line
                        for (var i = 0; i < depth; i++)
                            ws += tab;
                        stack.push(ws)
                    }
                break;
                case '}' :
                    --depth;
                    for (var i = 0; i < depth; i++)
                        ws += tab
                    stack.push(ws) 
                    stack.push(curr)
                break;
                case ']' :
                    --depth;
                    if (prev != '[') { // we want to keep an empty array on the same line
                        for (var i = 0; i < depth; i++)
                            ws += tab;
                        stack.push(ws)
                    }
                    stack.push(curr)
                break;
                case ',' : 
                    stack.push(curr)
                    if (next != '{') { // this is a personal style preference, not standard
                        for (var i = 0; i < depth; i++)
                            ws += tab;
                        stack.push(ws)        
                    }
                break;
                default :
                    stack.push(curr)
            }
        } else {
            word.push(curr)
        }
    }
    return stack.join('')
}