What's the opposite of JSON.stringify?

Question

What's the opposite of JSON.stringify?

Currently, I am converting an object to a string, such as {'foo': 'bar'}

What is the process for converting the string back into an object?

Answer 1

Answer №1

To properly handle your valid JSON string, you must utilize the JSON.parse() method.

var data = '{"name":"John", "age":30, "city":"New York"}';
try {
  var parsedData = JSON.parse(data); // this is how you parse a string into JSON 
  document.body.innerHTML += parsedData.name;
} catch (error) {
  console.error(error);
}

Answer 2

To properly handle your valid JSON string, you must utilize the JSON.parse() method.

var data = '{"name":"John", "age":30, "city":"New York"}';
try {
  var parsedData = JSON.parse(data); // this is how you parse a string into JSON 
  document.body.innerHTML += parsedData.name;
} catch (error) {
  console.error(error);
}

Answer 3

Answer №2

JSON.stringify and JSON.parse are two complementary functions that work together in handling JSON data.

Answer 4

JSON.stringify and JSON.parse are two complementary functions that work together in handling JSON data.

Answer 5

Answer №3

When using `JSON.stringify` and `JSON.parse`, they are often seen as opposites, with the following pattern typically yielding two objects that are "the same":

var obj = ...;
var json = JSON.stringify(obj);  
var obj2 = JSON.parse(json);

Although this method usually works well for simple objects, there are some limitations to be mindful of.

This helper function, jsonrepack, can help illustrate these limitations:

function jsonrepack( obj ) { return JSON.parse(JSON.stringify(obj) ); }

Only own properties are retained, losing prototypes:

var MyClass = function() { this.foo="foo"; } 
MyClass.prototype = { bar:"bar" }

var o = new MyClass();
var oo = jsonrepack(o);
console.log(oo.bar); // undefined
console.log( oo instanceof MyClass ); // false

Identity is lost:

var o = {};
var oo = jsonrepack(o);
console.log( o === oo ); // false

Functions do not survive:

jsonrepack( { f:function(){} } ); // Returns {}

Date objects become strings:

jsonrepack(new Date(1990,2,1)); // Returns '1990-02-01T16:00:00.000Z'

Undefined values do not survive:

var v = { x:undefined }
console.log("x" in v);              // true
console.log("x" in jsonrepack(v));  // false

Objects with a toJSON function may behave unexpectedly.

x = { f:"foo", toJSON:function(){ return "EGAD"; } }
jsonrepack(x) // Returns 'EGAD'

There are likely issues with other built-in types as well. To overcome some limitations, additional parameters of JSON.parse and JSON.stringify can be utilized.

For example:

function MyClass (v) {
   this.date = new Date(v.year,1,1);
   this.name = "an object";
};

MyClass.prototype.dance = function() {console.log("I'm dancing"); }

var o = new MyClass({year:2010});
var s = JSON.stringify(o);

// Smart unpack function
var o2 = JSON.parse( s, function(k,v){
  if(k==="") { 
     var rv = new MyClass(1990,0,0);
     rv.date = v.date;
     rv.name = v.name;
     return rv
  } else if(k==="date") {
    return new Date( Date.parse(v) );
  } else { return v; } } );

console.log(o);             // { date: <Mon Feb 01 2010 ...>, name: 'an object' }
console.log(o.constructor); // [Function: MyClass]
o.dance();                  // I'm dancing

console.log(o2);            // { date: <Mon Feb 01 2010 ...>, name: 'an object' }
console.log(o2.constructor) // [Function: MyClass]        
o2.dance();                 // I'm dancing

Answer 6

When using `JSON.stringify` and `JSON.parse`, they are often seen as opposites, with the following pattern typically yielding two objects that are "the same":

var obj = ...;
var json = JSON.stringify(obj);  
var obj2 = JSON.parse(json);

Although this method usually works well for simple objects, there are some limitations to be mindful of.

This helper function, jsonrepack, can help illustrate these limitations:

function jsonrepack( obj ) { return JSON.parse(JSON.stringify(obj) ); }

Only own properties are retained, losing prototypes:

var MyClass = function() { this.foo="foo"; } 
MyClass.prototype = { bar:"bar" }

var o = new MyClass();
var oo = jsonrepack(o);
console.log(oo.bar); // undefined
console.log( oo instanceof MyClass ); // false

Identity is lost:

var o = {};
var oo = jsonrepack(o);
console.log( o === oo ); // false

Functions do not survive:

jsonrepack( { f:function(){} } ); // Returns {}

Date objects become strings:

jsonrepack(new Date(1990,2,1)); // Returns '1990-02-01T16:00:00.000Z'

Undefined values do not survive:

var v = { x:undefined }
console.log("x" in v);              // true
console.log("x" in jsonrepack(v));  // false

Objects with a toJSON function may behave unexpectedly.

x = { f:"foo", toJSON:function(){ return "EGAD"; } }
jsonrepack(x) // Returns 'EGAD'

There are likely issues with other built-in types as well. To overcome some limitations, additional parameters of JSON.parse and JSON.stringify can be utilized.

For example:

function MyClass (v) {
   this.date = new Date(v.year,1,1);
   this.name = "an object";
};

MyClass.prototype.dance = function() {console.log("I'm dancing"); }

var o = new MyClass({year:2010});
var s = JSON.stringify(o);

// Smart unpack function
var o2 = JSON.parse( s, function(k,v){
  if(k==="") { 
     var rv = new MyClass(1990,0,0);
     rv.date = v.date;
     rv.name = v.name;
     return rv
  } else if(k==="date") {
    return new Date( Date.parse(v) );
  } else { return v; } } );

console.log(o);             // { date: <Mon Feb 01 2010 ...>, name: 'an object' }
console.log(o.constructor); // [Function: MyClass]
o.dance();                  // I'm dancing

console.log(o2);            // { date: <Mon Feb 01 2010 ...>, name: 'an object' }
console.log(o2.constructor) // [Function: MyClass]        
o2.dance();                 // I'm dancing

Answer 7

Answer №4

It is highly recommended to utilize the JSON.parse method for parsing JSON data.

If you prefer an alternative approach, consider the following:

var myObject = eval('(' + myJSONtext + ')');

Learn more about working with JSON in JavaScript

Find out why using the JavaScript eval function is discouraged

Answer 8

It is highly recommended to utilize the JSON.parse method for parsing JSON data.

If you prefer an alternative approach, consider the following:

var myObject = eval('(' + myJSONtext + ')');

Learn more about working with JSON in JavaScript

Find out why using the JavaScript eval function is discouraged

Answer 9

Answer №5

http://example.com/jsbin-edit

The original JSON object provides developers with two essential methods.

1. JSON.parse()
2. JSON.stringify()

When using the JSON.parse() method, a JSON string can be transformed back into the original JavaScript object

var jsObj = JSON.parse(jsonStr);
The JSON.stringify() function takes a JavaScript object and converts it to its corresponding JSON format.
```
var jsonStr = JSON.stringify(jsObj);
```

Answer 10

http://example.com/jsbin-edit

The original JSON object provides developers with two essential methods.

1. JSON.parse()
2. JSON.stringify()

When using the JSON.parse() method, a JSON string can be transformed back into the original JavaScript object

var jsObj = JSON.parse(jsonStr);
The JSON.stringify() function takes a JavaScript object and converts it to its corresponding JSON format.
```
var jsonStr = JSON.stringify(jsObj);
```

Answer 11

Answer №6

What do you think of this solution?

let parsedData = new Function('return ' + serializedJSON )();

A much more secure option compared to using eval.

let serializedJSON = '{"apple":"banana"}';
let parsedData = new Function('return ' + serializedJSON)();
console.log(parsedData.apple);

Answer 12

What do you think of this solution?

let parsedData = new Function('return ' + serializedJSON )();

A much more secure option compared to using eval.

let serializedJSON = '{"apple":"banana"}';
let parsedData = new Function('return ' + serializedJSON)();
console.log(parsedData.apple);

Answer 13

Answer №7

Take a look at this incredible resource.
http://jsfiddle.net/RT78Y/

Here's the code snippet:

var data = {};
data.name="codingisfun";
data.age=30;
data.phone=987654321;
debugger;
var dataString = JSON.stringify(data);
alert(dataString);
var newData = JSON.parse(dataString);
alert(newData);

Answer 14

Take a look at this incredible resource.
http://jsfiddle.net/RT78Y/

Here's the code snippet:

var data = {};
data.name="codingisfun";
data.age=30;
data.phone=987654321;
debugger;
var dataString = JSON.stringify(data);
alert(dataString);
var newData = JSON.parse(dataString);
alert(newData);

Answer 15

Answer №8

Is this partial solution a viable option?

I am considering storing a global object, called 'bigobj', with both data and methods using a Config node instead of relying on an external library. This 'bigobj' will be used in multiple function nodes within my flow:

It may seem unusual, but it does work: The structure of the global variable 'bigobj':

{
some[]more[]{dx:"here"} , // array of objects with another array of objects. The 'Config' node necessitates JSON.
.....
 "get_dx": "function( d,p) {  return this.some[d].more[p].dx; }"  // a test function
}

In essence, it is a JSON representation of a function.... all condensed into one line.

Implementation: Within a function node:

var bigO = global.get("bigobj");

function callJSONMethod(obj, fname, a, b, c, d){
    var wrap = s => "{ return " + obj[fname] + " };"
    var func = new Function(wrap(obj[fname]));
    return func.call( null ).call( obj, a, b, c, d);
}

msg.payload = callJSONMethod(bigO, "get_dx", 2, 2); 
return msg;

This code snippet returns "here", which is quite surprising!

This means I need to include the function callJSONMethod() in every function block that utilizes bigobj.... although this might be acceptable.

Warm regards

Answer 16

Is this partial solution a viable option?

I am considering storing a global object, called 'bigobj', with both data and methods using a Config node instead of relying on an external library. This 'bigobj' will be used in multiple function nodes within my flow:

It may seem unusual, but it does work: The structure of the global variable 'bigobj':

{
some[]more[]{dx:"here"} , // array of objects with another array of objects. The 'Config' node necessitates JSON.
.....
 "get_dx": "function( d,p) {  return this.some[d].more[p].dx; }"  // a test function
}

In essence, it is a JSON representation of a function.... all condensed into one line.

Implementation: Within a function node:

var bigO = global.get("bigobj");

function callJSONMethod(obj, fname, a, b, c, d){
    var wrap = s => "{ return " + obj[fname] + " };"
    var func = new Function(wrap(obj[fname]));
    return func.call( null ).call( obj, a, b, c, d);
}

msg.payload = callJSONMethod(bigO, "get_dx", 2, 2); 
return msg;

This code snippet returns "here", which is quite surprising!

This means I need to include the function callJSONMethod() in every function block that utilizes bigobj.... although this might be acceptable.

Warm regards

What's the opposite of JSON.stringify?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

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