(First try of) port of Node.js' util.inspect to JSON.stringify

index.js

var inspect = function(obj, showHidden, depth, colors){
	var ctx = {
		style: /*colors ? stylyze : */function(a){return a;}, //todo
		seen: []
	};
	return formatValue(ctx, obj, 2);
}

var _reName = /(\n\s+)"([A-Za-z_$][\w$]*)"/g;
var _reValue = /\"([^\n]*)\"(?=,?\n)/g;

function formatValue(ctx, obj, intent){
	var style = ctx.style;
	
	function format(key, val){
		var type = typeof val;
		//primitives
		switch(type){
			case "object":
				if(val === null) type = "null";
				else switch(Object.prototype.toString.call(val)){
				    case "[object Date]":
				    	return style(Data.prototype.toUTCString.call(val), "date");
				    case "[object RegExp]":
				    	return style(RegExp.prototype.toString.call(val), "regexp");
				    case "[object Error]":
				    	return "[" + Error.prototype.toString.call(val) + "]";
					//case "[object Array]":
				    //case "[object Object]":
				    default:
				    	if(ctx.seen.indexOf(obj) === -1){
				    		ctx.seen.push(obj);
				    		return val;
				    	} else return style("[Circular]", "special");
				}
			case "undefined":
			case "number":
			case "boolean":
				return style("" + val, type);
			case "string":
				val = '\''+String(val).replace(/^"|"$/g,"").replace(/'/g,"\\'").replace(/\\"/g,'"')+'\'';
				return style(val, type);
			case "function":
				return style("[Function" + (val.name && (": " + val.name) ) + "]", "special");
			default:
				return style(""+val, "special"); //unknown type
		}
	};
	return JSON.stringify(obj, format, intent || 2).replace(_reName, "$1$2").replace(_reValue, "$1");
}