Js object to json array simple implementation case

function obj2Str(obj){ 
switch(typeof(obj)){ 
case 'object': 
var ret = []; 
if (obj instanceof Array){ 
for (var i = 0, len = obj.length; i < len; i++){ 
ret.push(obj2Str(obj[i])); 
} 
return '[' + ret.join(',') + ']'; 
} 
else if (obj instanceof RegExp){ 
return obj.toString(); 
} 
else{ 
for (var a in obj){ 
ret.push(a + ':' + obj2Str(obj[a])); 
} 
return '{' + ret.join(',') + '}'; 
} 
case 'function': 
return 'function() {}'; 
case 'number': 
return obj.toString(); 
case 'string': 
return """ + obj.replace(/(\|")/g, "\$1").replace(/n|r|t/g, function(a) {return ("n"==a)?"\n":("r"==a)?"\r":("t"==a)?"\t":"";}) + """; 
case 'boolean': 
return obj.toString(); 
default: 
return obj.toString(); 
} 
}