去除对象中值为null、undefined、“”的字段

function removeEmptyField(obj) {
        var newObj = {};
        if(typeof obj == "string"){
            obj = JSON.parse(obj);
        }
        if(obj instanceof Array){
            newObj = [];
        }
        if(obj instanceof Object){
            for(var attr in obj){
                if(obj.hasOwnProperty(attr) && obj[attr] !== "" && obj[attr] !== null && obj[attr] !== undefined){
                    if(obj[attr] instanceof Object){
                        newObj[attr] = removeEmptyField(obj[attr]);
                    }else if(typeof obj[attr] == "string" && ((obj[attr].indexOf("{") > -1 && obj[attr].indexOf("}") > -1) || (obj[attr].indexOf("[") > -1 && obj[attr].indexOf("]") > -1))){
                        try{
                            var attrObj = JSON.parse(obj[attr]);
                            if(attrObj instanceof Object){
                                newObj[attr] = removeEmptyField(attrObj);
                            }
                        }catch (e){
                            newObj[attr] = obj[attr];
                        }
                    }else{
                        newObj[attr] = obj[attr];
                    }
                }
            }
        }
        return newObj;
    }

function stringifyNoEmptyField(obj){
        var newObj = removeEmptyField(obj);
        for(var attr in newObj){
            if(newObj.hasOwnProperty(attr) && newObj[attr] instanceof Array){
                newObj[attr] = JSON.stringify(newObj[attr]);
            }
        }
        return JSON.stringify(newObj);
    }