intro:
I'm trying to write a deep copy method, but need to keep track of my visited nodes, so that I can link to the previously visitedNode instead of deep copying forever until stack overflow.
attempts:
var visitedNodes = {};
var obj = {}; obj.a = obj; // circular; can't use JSON.stringify)
var obj2 = {};
visitedNodes[obj] = "should need key obj (not obj2) to access this string";
console.log(visitedNodes[obj2]); // logs the string unfortunately
I don't have a unique way of storing the memory location -- it stores itself at [object Object] and I can't use JSON.stringify because it's a circular structure
I tried using var visitedNodes = new Map(); but still no dice
My current approach is to utilize the Array.prototype.indexOf function, but I don't know if it works with circular structures either, because I'm getting a stack overflow here too!!!
this.clone = function (item, visitedNodes) {
visitedNodes = visitedNodes || [];
if (typeof item === "object" && !Array.isArray(item)) {
if (visitedNodes.indexOf(item) === -1) {
var cloneObject = {};
visitedNodes.push(cloneObject);
for (var i in item) {
if (item.hasOwnProperty(i)) {
cloneObject[i] = this.clone(item[i], visitedNodes);
}
}
return cloneObject;
} else {
return visitedNodes[visitedNodes.indexOf(item)];
}
}
else if (typeof item === "object" && Array.isArray(item)) {
if (visitedNodes.indexOf(item) === -1) {
var cloneArray = [];
visitedNodes.push(cloneArray);
for (var j = 0; j < item.length; j++) {
cloneArray.push(this.clone(item[j], visitedNodes));
}
return cloneArray;
} else {
return visitedNodes[visitedNodes.indexOf(item)];
}
}
return item; // not object, not array, therefore primitive
};
the question:
Anyone have any ideas for getting a unique memory address so I can determine if I've been to the Object's reference before? I believe I could construct a unique hash based off Object.keys() and Object.prototype.constructor but that seems absurd and will give false positives if constructor is the same and the child keys are the same as the parent
In visitedNodes save the original reference, and create another array to save with same index the clone object to use when is a reference.
function deepClone(obj) {
var visitedNodes = [];
var clonedCopy = [];
function clone(item) {
if (typeof item === "object" && !Array.isArray(item)) {
if (visitedNodes.indexOf(item) === -1) {
visitedNodes.push(item);
var cloneObject = {};
clonedCopy.push(cloneObject);
for (var i in item) {
if (item.hasOwnProperty(i)) {
cloneObject[i] = clone(item[i]);
}
}
return cloneObject;
} else {
return clonedCopy[visitedNodes.indexOf(item)];
}
}
else if (typeof item === "object" && Array.isArray(item)) {
if (visitedNodes.indexOf(item) === -1) {
var cloneArray = [];
visitedNodes.push(item);
clonedCopy.push(cloneArray);
for (var j = 0; j < item.length; j++) {
cloneArray.push(clone(item[j]));
}
return cloneArray;
} else {
return clonedCopy[visitedNodes.indexOf(item)];
}
}
return item; // not object, not array, therefore primitive
}
return clone(obj);
}
var obj = {b: 'hello'};
obj.a = { c: obj };
var dolly = deepClone(obj);
obj.d = 'hello2';
console.log(obj);
console.log(dolly);
the code running example:
http://jsbin.com/favekexiba/1/watch?js,console
The code in the answer of Fetz works great but breaks on Date objects. Here is a patched version:
const visitedNodes = [];
const clonedCopy = [];
function clone(item) {
if (typeof item === 'object') {
if (item instanceof Date) { // Date
if (visitedNodes.indexOf(item) === -1) {
visitedNodes.push(item);
var cloneObject = new Date(item);
clonedCopy.push(cloneObject);
return cloneObject;
}
return clonedCopy[visitedNodes.indexOf(item)];
} else if (XMLDocument && item instanceof XMLDocument) { // XML Document
if (visitedNodes.indexOf(item) === -1) {
visitedNodes.push(item);
const cloneObject = item.implementation.createDocument(item.documentElement.namespaceURI, null, null);
const newNode = cloneObject.importNode(item.documentElement, true);
cloneObject.appendChild(newNode);
clonedCopy.push(cloneObject);
return cloneObject;
}
return clonedCopy[visitedNodes.indexOf(item)];
} else if (!Array.isArray(item)) { // Object
if (visitedNodes.indexOf(item) === -1) {
visitedNodes.push(item);
var cloneObject = {};
clonedCopy.push(cloneObject);
for (const i in item) {
if (item.hasOwnProperty(i)) {
cloneObject[i] = clone(item[i]);
}
}
return cloneObject;
}
return clonedCopy[visitedNodes.indexOf(item)];
} else if (Array.isArray(item)) { // Array
if (visitedNodes.indexOf(item) === -1) {
const cloneArray = [];
visitedNodes.push(item);
clonedCopy.push(cloneArray);
for (let j = 0; j < item.length; j++) {
cloneArray.push(clone(item[j]));
}
return cloneArray;
}
return clonedCopy[visitedNodes.indexOf(item)];
}
}
return item; // not date, not object, not array, therefore primitive
}
return clone(obj);
I would've preferred to edit the answer of Fetz but the edit queue is full.
edit 19/07/2017: Added XML Document cloning as well
Is there an easy way of knowing if and array contains all elements of another array?
Example:
var myarray = [1,2,3];
var searchinarray = [1,2,3,4,5];
searchinarray contains all elements of myarray, so this should return true.
Regards
Here is an implementation of that function:
function contains(a, s) {
for(var i = 0, l = s.length; i < l; i++) {
if(!~a.indexOf(s[i])) {
return false;
}
}
return true;
}
This shows that it does what you describe:
> var myarray = [1,2,3];
> var searchinarray = [1,2,3,4,5];
> contains(myarray, searchinarray)
false
> contains(myarray, [1,2])
true
> contains(myarray, [2,3])
true
A contains function should only visit members of the array to be contained that exist, e.g.
var myArray = [1,,2];
var searchInArray = [1,2,3];
contains(myArray, searchInArray);
should return true, however a simple looping solution will return false as myArray[1] doesn't exist so will return undefined, which is not present in the searchInArray. To easily avoid that and not use a hasOwnProperty test, you can use the Array every method:
function contains(searchIn, array) {
return array.every(function(v){return this.indexOf(v) != -1}, searchIn);
}
so that:
var a = [1,,3];
var s = [1,2,3,4,5];
console.log(contains(s, a)); // true
You can add a contains method to all instances of Array if you wish:
if (typeof Array.prototype.contains == 'undefined') {
Array.prototype.contains = function(a) {
return a.every(function(v, i) {
return this.indexOf(v) != -1;
}, this);
}
}
console.log(s.contains(a)); // true
console.log(s.contains([1,9])); // false
You may need a polyfill for browsers that don't have .every (IE 8?).
function compare(array, contains_array) {
for(var i = 0; i < array.length; i++) {
if(contains_array.indexOf(array[i]) == -1) return false;
}
return true;
}
compare(myarray, searchinarray);
I have two multidimensional arrays:
first is something like (['one','one','three'],['four','five',five'],['one','one','one'])
and the second one is like this (['one','one','nine'],['one','one','one'],['two','two'],['two','two','two']...)
Now, what I want is to find match first index of first array with second array, but position of at least first two indexes from boths array must match also, eg.:
first_array (['one','one','three'],['four','five',five'],['one','one','one'])
will match
second_array (['one','one','nine'],['one','one','one'],['two','two']['two','two','two']...)
and output would be eg. 'alert('Match.').
I have tried
for(i=0; i<1; i++){
if(first_array[0] == second_array) console.log('Match');
else console.log('No match');
}
but I constantly get 'No match' although there is a match.
P.S. in 'for' loop, my i is i<1 because I want to compare only first index of first_array with complete second_array.
Thanks in advance
var md1 = [['one','one','three'],['four','five','five'],['one','one','one']];
var md2 = [['one','one','nine'],['one','one','one'],['two','two'],['two','two','two']];
//Iterate through all elements in first array
for(var x = 0; x < md1.length; x++){
//Iterate through all elements in second array
for(var y = 0; y < md2.length; y++){
/*This causes us to compare all elements
in first array to each element in second array
Since md1[x] stays fixed while md2[y] iterates through second array.
We compare the first two indexes of each array in conditional
*/
if(md1[x][0] == md2[y][0] && md1[x][1] == md2[y][1]){
alert("match found");
alert("Array 1 element with index " + x + " matches Array 2 element with index " + y);
}
}
}
Working Example http://jsfiddle.net/2nxBb/1/
Possible duplicate of How to compare arrays in JavaScript?.
For a strict array comparison, check their length and values like so:
var a1 = [1, 2, 3];
var a2 = [1, 2, 3];
array_compare(a1, a2);
function array_compare(a1, a2) {
if(a1.length != a2.length) {
return false;
}
for(var i in a1) {
// Don't forget to check for arrays in our arrays.
if(a1[i] instanceof Array && a2[i] instanceof Array) {
if(!array_compare(a1[i], a2[i])) {
return false;
}
}
else if(a1[i] != a2[i]) {
return false;
}
}
return true;
}
2 way, more simple if this enough for u
JSON.stringify(tree1) === JSON.stringify(tree2)
if not, use this: recursively handles multidimensional arrays and objects
treesAreSame(tree1, tree2) {
if (tree1 === tree2) {
return true;
}
if (tree1 === null || tree1 === undefined || tree2 == null) {
return false;
}
if (Array.isArray(tree1) !== Array.isArray(tree2)) {
return false;
}
if (tree1.length !== tree2.length) {
return false;
}
if (isArray(tree1)) {
for (let i = 0; i < tree1.length; ++i) {
let t1 = tree1[i];
let t2 = tree2[i];
if (isArray(t1) || isObject(t1)) {
if (!treesAreSame(t1, t2)) {
return false;
}
} else {
if (t1 !== t2) {
return false;
}
}
}
}
if (isObject(tree1)) {
for (const k of Object.keys(tree1)) {
let t1 = tree1[k];
let t2 = tree2[k];
if (isArray(t1) || isObject(t1)) {
if (!treesAreSame(t1, t2)) {
return false;
}
} else {
if (t1 !== t2) {
return false;
}
}
}
}
return true;
};
isObject(a) {
return (!!a) && (a.constructor === Object);
};
isArray(a) {
return (!!a) && (a.constructor === Array);
};
I wanna set the value in a JSON using a path string like this "a.0.b" for a JSON that looks like this:
{
a: [
{
b: 'c'
}
]
}
I came up with this solution but I wonder if there is a simpler way to write this:
function setValue(path, value, json) {
var keys = path.split('.');
_.reduce(keys, function(obj, key, i) {
if (i === keys.length - 1) {
obj[key] = value;
} else {
return obj[key];
}
}, json);
}
so calling setValue('a.0.b', 'd', {a:[{b:'c'}]}) would change the json to {a:[{b:'d'}]}
Here's a solution. I benchmarked the two possible solutions and it seems looping over object and path is faster than using the reduce function. See the JSPerf tests here: http://jsperf.com/set-value-in-json-by-a-path-using-lodash-or-underscore
function setValue(path, val, obj) {
var fields = path.split('.');
var result = obj;
for (var i = 0, n = fields.length; i < n && result !== undefined; i++) {
var field = fields[i];
if (i === n - 1) {
result[field] = val;
} else {
if (typeof result[field] === 'undefined' || !_.isObject(result[field])) {
result[field] = {};
}
result = result[field];
}
}
}
I have a nested JSON object that I need to loop through, and the value of each key could be a String, JSON array or another JSON object. Depending on the type of object, I need to carry out different operations. Is there any way I can check the type of the object to see if it is a String, JSON object or JSON array?
I tried using typeof and instanceof but both didn't seem to work, as typeof will return an object for both JSON object and array, and instanceof gives an error when I do obj instanceof JSON.
To be more specific, after parsing the JSON into a JS object, is there any way I can check if it is a normal string, or an object with keys and values (from a JSON object), or an array (from a JSON array)?
For example:
JSON
var data = "{'hi':
{'hello':
['hi1','hi2']
},
'hey':'words'
}";
Sample JavaScript
var jsonObj = JSON.parse(data);
var path = ["hi","hello"];
function check(jsonObj, path) {
var parent = jsonObj;
for (var i = 0; i < path.length-1; i++) {
var key = path[i];
if (parent != undefined) {
parent = parent[key];
}
}
if (parent != undefined) {
var endLength = path.length - 1;
var child = parent[path[endLength]];
//if child is a string, add some text
//if child is an object, edit the key/value
//if child is an array, add a new element
//if child does not exist, add a new key/value
}
}
How do I carry out the object checking as shown above?
I'd check the constructor attribute.
e.g.
var stringConstructor = "test".constructor;
var arrayConstructor = [].constructor;
var objectConstructor = ({}).constructor;
function whatIsIt(object) {
if (object === null) {
return "null";
}
if (object === undefined) {
return "undefined";
}
if (object.constructor === stringConstructor) {
return "String";
}
if (object.constructor === arrayConstructor) {
return "Array";
}
if (object.constructor === objectConstructor) {
return "Object";
}
{
return "don't know";
}
}
var testSubjects = ["string", [1,2,3], {foo: "bar"}, 4];
for (var i=0, len = testSubjects.length; i < len; i++) {
alert(whatIsIt(testSubjects[i]));
}
Edit: Added a null check and an undefined check.
You can use Array.isArray to check for arrays. Then typeof obj == 'string', and typeof obj == 'object'.
var s = 'a string', a = [], o = {}, i = 5;
function getType(p) {
if (Array.isArray(p)) return 'array';
else if (typeof p == 'string') return 'string';
else if (p != null && typeof p == 'object') return 'object';
else return 'other';
}
console.log("'s' is " + getType(s));
console.log("'a' is " + getType(a));
console.log("'o' is " + getType(o));
console.log("'i' is " + getType(i));
's' is string'a' is array 'o' is object'i' is other
An JSON object is an object. To check whether a type is an object type, evaluate the constructor property.
function isObject(obj)
{
return obj !== undefined && obj !== null && obj.constructor == Object;
}
The same applies to all other types:
function isArray(obj)
{
return obj !== undefined && obj !== null && obj.constructor == Array;
}
function isBoolean(obj)
{
return obj !== undefined && obj !== null && obj.constructor == Boolean;
}
function isFunction(obj)
{
return obj !== undefined && obj !== null && obj.constructor == Function;
}
function isNumber(obj)
{
return obj !== undefined && obj !== null && obj.constructor == Number;
}
function isString(obj)
{
return obj !== undefined && obj !== null && obj.constructor == String;
}
function isInstanced(obj)
{
if(obj === undefined || obj === null) { return false; }
if(isArray(obj)) { return false; }
if(isBoolean(obj)) { return false; }
if(isFunction(obj)) { return false; }
if(isNumber(obj)) { return false; }
if(isObject(obj)) { return false; }
if(isString(obj)) { return false; }
return true;
}
you can also try to parse the data and then check if you got object:
try {
var testIfJson = JSON.parse(data);
if (typeof testIfJson == "object"){
//Json
} else {
//Not Json
}
}
catch {
return false;
}
If you are trying to check the type of an object after you parse a JSON string, I suggest checking the constructor attribute:
obj.constructor == Array || obj.constructor == String || obj.constructor == Object
This will be a much faster check than typeof or instanceof.
If a JSON library does not return objects constructed with these functions, I would be very suspiciouse of it.
The answer by #PeterWilkinson didn't work for me because a constructor for a "typed" object is customized to the name of that object. I had to work with typeof
function isJson(obj) {
var t = typeof obj;
return ['boolean', 'number', 'string', 'symbol', 'function'].indexOf(t) == -1;
}
You could make your own constructor for JSON parsing:
var JSONObj = function(obj) { $.extend(this, JSON.parse(obj)); }
var test = new JSONObj('{"a": "apple"}');
//{a: "apple"}
Then check instanceof to see if it needed parsing originally
test instanceof JSONObj
I wrote an npm module to solve this problem. It's available here:
object-types: a module for finding what literal types underly objects
Install
npm install --save object-types
Usage
const objectTypes = require('object-types');
objectTypes({});
//=> 'object'
objectTypes([]);
//=> 'array'
objectTypes(new Object(true));
//=> 'boolean'
Take a look, it should solve your exact problem. Let me know if you have any questions! https://github.com/dawsonbotsford/object-types
Why not check Number - a bit shorter and works in IE/Chrome/FF/node.js
function whatIsIt(object) {
if (object === null) {
return "null";
}
else if (object === undefined) {
return "undefined";
}
if (object.constructor.name) {
return object.constructor.name;
}
else { // last chance 4 IE: "\nfunction Number() {\n [native code]\n}\n" / node.js: "function String() { [native code] }"
var name = object.constructor.toString().split(' ');
if (name && name.length > 1) {
name = name[1];
return name.substr(0, name.indexOf('('));
}
else { // unreachable now(?)
return "don't know";
}
}
}
var testSubjects = ["string", [1,2,3], {foo: "bar"}, 4];
// Test all options
console.log(whatIsIt(null));
console.log(whatIsIt());
for (var i=0, len = testSubjects.length; i < len; i++) {
console.log(whatIsIt(testSubjects[i]));
}
I combine the typeof operator with a check of the constructor attribute (by Peter):
var typeOf = function(object) {
var firstShot = typeof object;
if (firstShot !== 'object') {
return firstShot;
}
else if (object.constructor === [].constructor) {
return 'array';
}
else if (object.constructor === {}.constructor) {
return 'object';
}
else if (object === null) {
return 'null';
}
else {
return 'don\'t know';
}
}
// Test
var testSubjects = [true, false, 1, 2.3, 'string', [4,5,6], {foo: 'bar'}, null, undefined];
console.log(['typeOf()', 'input parameter'].join('\t'))
console.log(new Array(28).join('-'));
testSubjects.map(function(testSubject){
console.log([typeOf(testSubject), JSON.stringify(testSubject)].join('\t\t'));
});
Result:
typeOf() input parameter
---------------------------
boolean true
boolean false
number 1
number 2.3
string "string"
array [4,5,6]
object {"foo":"bar"}
null null
undefined
I know this is a very old question with good answers. However, it seems that it's still possible to add my 2ยข to it.
Assuming that you're trying to test not a JSON object itself but a String that is formatted as a JSON (which seems to be the case in your var data), you could use the following function that returns a boolean (is or is not a 'JSON'):
function isJsonString( jsonString ) {
// This function below ('printError') can be used to print details about the error, if any.
// Please, refer to the original article (see the end of this post)
// for more details. I suppressed details to keep the code clean.
//
let printError = function(error, explicit) {
console.log(`[${explicit ? 'EXPLICIT' : 'INEXPLICIT'}] ${error.name}: ${error.message}`);
}
try {
JSON.parse( jsonString );
return true; // It's a valid JSON format
} catch (e) {
return false; // It's not a valid JSON format
}
}
Here are some examples of using the function above:
console.log('\n1 -----------------');
let j = "abc";
console.log( j, isJsonString(j) );
console.log('\n2 -----------------');
j = `{"abc": "def"}`;
console.log( j, isJsonString(j) );
console.log('\n3 -----------------');
j = '{"abc": "def}';
console.log( j, isJsonString(j) );
console.log('\n4 -----------------');
j = '{}';
console.log( j, isJsonString(j) );
console.log('\n5 -----------------');
j = '[{}]';
console.log( j, isJsonString(j) );
console.log('\n6 -----------------');
j = '[{},]';
console.log( j, isJsonString(j) );
console.log('\n7 -----------------');
j = '[{"a":1, "b": 2}, {"c":3}]';
console.log( j, isJsonString(j) );
When you run the code above, you will get the following results:
1 -----------------
abc false
2 -----------------
{"abc": "def"} true
3 -----------------
{"abc": "def} false
4 -----------------
{} true
5 -----------------
[{}] true
6 -----------------
[{},] false
7 -----------------
[{"a":1, "b": 2}, {"c":3}] true
Please, try the snippet below and let us know if this works for you. :)
IMPORTANT: the function presented in this post was adapted from https://airbrake.io/blog/javascript-error-handling/syntaxerror-json-parse-bad-parsing where you can find more and interesting details about the JSON.parse() function.
function isJsonString( jsonString ) {
let printError = function(error, explicit) {
console.log(`[${explicit ? 'EXPLICIT' : 'INEXPLICIT'}] ${error.name}: ${error.message}`);
}
try {
JSON.parse( jsonString );
return true; // It's a valid JSON format
} catch (e) {
return false; // It's not a valid JSON format
}
}
console.log('\n1 -----------------');
let j = "abc";
console.log( j, isJsonString(j) );
console.log('\n2 -----------------');
j = `{"abc": "def"}`;
console.log( j, isJsonString(j) );
console.log('\n3 -----------------');
j = '{"abc": "def}';
console.log( j, isJsonString(j) );
console.log('\n4 -----------------');
j = '{}';
console.log( j, isJsonString(j) );
console.log('\n5 -----------------');
j = '[{}]';
console.log( j, isJsonString(j) );
console.log('\n6 -----------------');
j = '[{},]';
console.log( j, isJsonString(j) );
console.log('\n7 -----------------');
j = '[{"a":1, "b": 2}, {"c":3}]';
console.log( j, isJsonString(j) );
Try, Catch block will help you to solve this
Make a function
function IsJson(str) {
try {
JSON.parse(str);
} catch (e) {
return false;
}
return true;
}
Example:
console.log(IsJson('abc')) // false
console.log(IsJson('[{"type":"email","detail":"john#example.com"}]')) // true
Try this
if ( typeof is_json != "function" )
function is_json( _obj )
{
var _has_keys = 0 ;
for( var _pr in _obj )
{
if ( _obj.hasOwnProperty( _pr ) && !( /^\d+$/.test( _pr ) ) )
{
_has_keys = 1 ;
break ;
}
}
return ( _has_keys && _obj.constructor == Object && _obj.constructor != Array ) ? 1 : 0 ;
}
It works for the example below
var _a = { "name" : "me",
"surname" : "I",
"nickname" : {
"first" : "wow",
"second" : "super",
"morelevel" : {
"3level1" : 1,
"3level2" : 2,
"3level3" : 3
}
}
} ;
var _b = [ "name", "surname", "nickname" ] ;
var _c = "abcdefg" ;
console.log( is_json( _a ) );
console.log( is_json( _b ) );
console.log( is_json( _c ) );
Based on #Martin Wantke answer, but with some recommended improvements/adjusts...
// NOTE: Check JavaScript type. By Questor
function getJSType(valToChk) {
function isUndefined(valToChk) { return valToChk === undefined; }
function isNull(valToChk) { return valToChk === null; }
function isArray(valToChk) { return valToChk.constructor == Array; }
function isBoolean(valToChk) { return valToChk.constructor == Boolean; }
function isFunction(valToChk) { return valToChk.constructor == Function; }
function isNumber(valToChk) { return valToChk.constructor == Number; }
function isString(valToChk) { return valToChk.constructor == String; }
function isObject(valToChk) { return valToChk.constructor == Object; }
if(isUndefined(valToChk)) { return "undefined"; }
if(isNull(valToChk)) { return "null"; }
if(isArray(valToChk)) { return "array"; }
if(isBoolean(valToChk)) { return "boolean"; }
if(isFunction(valToChk)) { return "function"; }
if(isNumber(valToChk)) { return "number"; }
if(isString(valToChk)) { return "string"; }
if(isObject(valToChk)) { return "object"; }
}
NOTE: I found this approach very didactic, so I submitted this answer.
Peter's answer with an additional check! Of course, not 100% guaranteed!
var isJson = false;
outPutValue = ""
var objectConstructor = {}.constructor;
if(jsonToCheck.constructor === objectConstructor){
outPutValue = JSON.stringify(jsonToCheck);
try{
JSON.parse(outPutValue);
isJson = true;
}catch(err){
isJson = false;
}
}
if(isJson){
alert("Is json |" + JSON.stringify(jsonToCheck) + "|");
}else{
alert("Is other!");
}
I have a pretty lazy answer to this, which will not throw an error if you try to parse a string/other values.
const checkForJson = (value) => {
if (typeof value !== "string") return false;
return value[0] === "{" && value[value.length - 1] === "}";
}
You can use this to check the value of your keys while you make some recursive func; sorry if this doesn't answer the question completely
Ofc this isn't the most elegant solution and will fail when a string actually starts with "{" and ends with "}" although those use cases would be rare, and if you really wanted, you can check for a presence of quotes or other nonsense... anyway, use at your own discretion.
TLDR: it's not bulletproof, but it's simple and works for the vast majority of use cases.
lodash is also the best bet to check these things.
function Foo() {
this.a = 1;
}
_.isPlainObject(new Foo);
// => false
_.isPlainObject([1, 2, 3]);
// => false
_.isPlainObject({ 'x': 0, 'y': 0 });
// => true
_.isPlainObject(Object.create(null));
// => true
https://www.npmjs.com/package/lodash
https://lodash.com/docs/#isPlainObject
Quickly check for a JSON structure using lodash-contrib:
const _ = require('lodash-contrib');
_.isJSON('{"car": "ferarri"}'); //true for stringified
_.isJSON({car: "ferarri"}); //true
Usage guide: this blog entry
try this dirty way
('' + obj).includes('{')