Converting an object to a string

Question

How can I convert a JavaScript object into a string?

Example:

var o = {a:1, b:2}
console.log(o)
console.log('Item: ' + o)

Output:

Object { a=1, b=2} // very nice readable output :)
Item: [object Object] // no idea what's inside :(

Answer 1

I would recommend using JSON.stringify, which converts the set of the variables in the object to a JSON string.

var obj = {
  name: 'myObj'
};

JSON.stringify(obj);

Most modern browsers support this method natively, but for those that don't, you can include a JS version.

Answer 2

Use javascript String() function

 String(yourobject); //returns [object Object]

or stringify()

JSON.stringify(yourobject)

Answer 3

Keeping it simple with console, you can just use a comma instead of a +. The + will try to convert the object into a string, whereas the comma will display it separately in the console.

Example:

var o = {a:1, b:2};
console.log(o);
console.log('Item: ' + o);
console.log('Item: ', o);   // :)

Output:

Object { a=1, b=2}           // useful
Item: [object Object]        // not useful
Item:  Object {a: 1, b: 2}   // Best of both worlds! :)

Reference: https://developer.mozilla.org/en-US/docs/Web/API/Console.log

Answer 4

Sure, to convert an object into a string, you either have to use your own method, such as:

function objToString (obj) {
    var str = '';
    for (var p in obj) {
        if (Object.prototype.hasOwnProperty.call(obj, p)) {
            str += p + '::' + obj[p] + '\n';
        }
    }
    return str;
}

Actually, the above just shows the general approach; you may wish to use something like http://phpjs.org/functions/var_export:578 or http://phpjs.org/functions/var_dump:604

or, if you are not using methods (functions as properties of your object), you may be able to use the new standard (but not implemented in older browsers, though you can find a utility to help with it for them too), JSON.stringify(). But again, that won't work if the object uses functions or other properties which aren't serializable to JSON.

Update:

A more modern solution would be:

function objToString (obj) {
    let str = '';
    for (const [p, val] of Object.entries(obj)) {
        str += `${p}::${val}\n`;
    }
    return str;
}

or:

function objToString (obj) {
    return Object.entries(obj).reduce((str, [p, val]) => {
        return `${str}${p}::${val}\n`;
    }, '');
}

Answer 5

EDIT Do not use this answer as it works only in some versions of Firefox. No other browsers support it. Use Gary Chambers solution.

toSource() is the function you are looking for which will write it out as JSON.

var object = {};
object.first = "test";
object.second = "test2";
alert(object.toSource());

Answer 6

One option:

console.log('Item: ' + JSON.stringify(o));

Another option (as soktinpk pointed out in the comments), and better for console debugging IMO:

console.log('Item: ', o);

Answer 7

None of the solutions here worked for me. JSON.stringify seems to be what a lot of people say, but it cuts out functions and seems pretty broken for some objects and arrays I tried when testing it.

I made my own solution which works in Chrome at least. Posting it here so anyone that looks this up on Google can find it.

//Make an object a string that evaluates to an equivalent object
//  Note that eval() seems tricky and sometimes you have to do
//  something like eval("a = " + yourString), then use the value
//  of a.
//
//  Also this leaves extra commas after everything, but JavaScript
//  ignores them.
function convertToText(obj) {
    //create an array that will later be joined into a string.
    var string = [];

    //is object
    //    Both arrays and objects seem to return "object"
    //    when typeof(obj) is applied to them. So instead
    //    I am checking to see if they have the property
    //    join, which normal objects don't have but
    //    arrays do.
    if (typeof(obj) == "object" && (obj.join == undefined)) {
        string.push("{");
        for (prop in obj) {
            string.push(prop, ": ", convertToText(obj[prop]), ",");
        };
        string.push("}");

    //is array
    } else if (typeof(obj) == "object" && !(obj.join == undefined)) {
        string.push("[")
        for(prop in obj) {
            string.push(convertToText(obj[prop]), ",");
        }
        string.push("]")

    //is function
    } else if (typeof(obj) == "function") {
        string.push(obj.toString())

    //all other values can be done with JSON.stringify
    } else {
        string.push(JSON.stringify(obj))
    }

    return string.join("")
}

EDIT: I know this code can be improved but just never got around to doing it. User andrey suggested an improvement here with the comment:

Here is a little bit changed code, which can handle 'null' and 'undefined', and also do not add excessive commas.

Use that at your own risk as I haven't verified it at all. Feel free to suggest any additional improvements as a comment.

Answer 8

If you're just outputting to the console, you can use console.log('string:', obj). Notice the comma.

Answer 9

In cases where you know the object is just a Boolean, Date, String, number etc... The javascript String() function works just fine. I recently found this useful in dealing with values coming from jquery's $.each function.

For example the following would convert all items in "value" to a string:

$.each(this, function (name, value) {
  alert(String(value));
});

More details here:

http://www.w3schools.com/jsref/jsref_string.asp

Answer 10

I was looking for this, and wrote a deep recursive one with indentation :

function objToString(obj, ndeep) {
  if(obj == null){ return String(obj); }
  switch(typeof obj){
    case "string": return '"'+obj+'"';
    case "function": return obj.name || obj.toString();
    case "object":
      var indent = Array(ndeep||1).join('\t'), isArray = Array.isArray(obj);
      return '{['[+isArray] + Object.keys(obj).map(function(key){
           return '\n\t' + indent + key + ': ' + objToString(obj[key], (ndeep||1)+1);
         }).join(',') + '\n' + indent + '}]'[+isArray];
    default: return obj.toString();
  }
}

Usage : objToString({ a: 1, b: { c: "test" } })

Answer 11

var obj={
name:'xyz',
Address:'123, Somestreet'
 }
var convertedString=JSON.stringify(obj) 
 console.log("literal object is",obj ,typeof obj);
 console.log("converted string :",convertedString);
 console.log(" convertedString type:",typeof convertedString);

Answer 12

There is actually one easy option (for recent browsers and Node.js) missing in the existing answers:

console.log('Item: %o', o);

I would prefer this as JSON.stringify() has certain limitations (e.g. with circular structures).

Answer 13

If you just want to see the object for debugging, you can use

var o = {a:1, b:2} 
console.dir(o)

Answer 14

1.

JSON.stringify(o);

Item: {"a":"1", "b":"2"}

2.

var o = {a:1, b:2};
var b=[]; Object.keys(o).forEach(function(k){b.push(k+":"+o[k]);});
b="{"+b.join(', ')+"}";
console.log('Item: ' + b);

Item: {a:1, b:2}

Answer 15

It appears JSON accept the second parameter that could help with functions - replacer, this solves the issue of converting in the most elegant way:

JSON.stringify(object, (key, val) => {
    if (typeof val === 'function') {
      return String(val);
    }
    return val;
  });

Answer 16

For non-nested objects:

Object.entries(o).map(x=>x.join(":")).join("\r\n")

Answer 17

JSON methods are quite inferior to the Gecko engine .toSource() primitive.

See the SO article response for comparison tests.

Also, the answer above refers to http://forums.devshed.com/javascript-development-115/tosource-with-arrays-in-ie-386109.html which, like JSON, (which the other article http://www.davidpirek.com/blog/object-to-string-how-to-deserialize-json uses via "ExtJs JSON encode source code") cannot handle circular references and is incomplete. The code below shows it's (spoof's) limitations (corrected to handle arrays and objects without content).

(direct link to code in //forums.devshed.com/ ... /tosource-with-arrays-in-ie-386109)

javascript:
Object.prototype.spoof=function(){
    if (this instanceof String){
      return '(new String("'+this.replace(/"/g, '\\"')+'"))';
    }
    var str=(this instanceof Array)
        ? '['
        : (this instanceof Object)
            ? '{'
            : '(';
    for (var i in this){
      if (this[i] != Object.prototype.spoof) {
        if (this instanceof Array == false) {
          str+=(i.match(/\W/))
              ? '"'+i.replace('"', '\\"')+'":'
              : i+':';
        }
        if (typeof this[i] == 'string'){
          str+='"'+this[i].replace('"', '\\"');
        }
        else if (this[i] instanceof Date){
          str+='new Date("'+this[i].toGMTString()+'")';
        }
        else if (this[i] instanceof Array || this[i] instanceof Object){
          str+=this[i].spoof();
        }
        else {
          str+=this[i];
        }
        str+=', ';
      }
    };
    str=/* fix */(str.length>2?str.substring(0, str.length-2):str)/* -ed */+(
        (this instanceof Array)
        ? ']'
        : (this instanceof Object)
            ? '}'
            : ')'
    );
    return str;
  };
for(i in objRA=[
    [   'Simple Raw Object source code:',
        '[new Array, new Object, new Boolean, new Number, ' +
            'new String, new RegExp, new Function, new Date]'   ] ,

    [   'Literal Instances source code:',
        '[ [], {}, true, 1, "", /./, function(){}, new Date() ]'    ] ,

    [   'some predefined entities:',
        '[JSON, Math, null, Infinity, NaN, ' +
            'void(0), Function, Array, Object, undefined]'      ]
    ])
alert([
    '\n\n\ntesting:',objRA[i][0],objRA[i][1],
    '\n.toSource()',(obj=eval(objRA[i][1])).toSource(),
    '\ntoSource() spoof:',obj.spoof()
].join('\n'));

which displays:

testing:
Simple Raw Object source code:
[new Array, new Object, new Boolean, new Number, new String,
          new RegExp, new Function, new Date]

.toSource()
[[], {}, (new Boolean(false)), (new Number(0)), (new String("")),
          /(?:)/, (function anonymous() {}), (new Date(1303248037722))]

toSource() spoof:
[[], {}, {}, {}, (new String("")),
          {}, {}, new Date("Tue, 19 Apr 2011 21:20:37 GMT")]

and

testing:
Literal Instances source code:
[ [], {}, true, 1, "", /./, function(){}, new Date() ]

.toSource()
[[], {}, true, 1, "", /./, (function () {}), (new Date(1303248055778))]

toSource() spoof:
[[], {}, true, 1, ", {}, {}, new Date("Tue, 19 Apr 2011 21:20:55 GMT")]

and

testing:
some predefined entities:
[JSON, Math, null, Infinity, NaN, void(0), Function, Array, Object, undefined]

.toSource()
[JSON, Math, null, Infinity, NaN, (void 0),
       function Function() {[native code]}, function Array() {[native code]},
              function Object() {[native code]}, (void 0)]

toSource() spoof:
[{}, {}, null, Infinity, NaN, undefined, {}, {}, {}, undefined]

Answer 18

stringify-object is a good npm library made by the yeoman team: https://www.npmjs.com/package/stringify-object

npm install stringify-object

then:

const stringifyObject = require('stringify-object');
stringifyObject(myCircularObject);

Obviously it's interesting only if you have circular object that would fail with JSON.stringify();

Answer 19

As firefox does not stringify some object as screen object ; if you want to have the same result such as : JSON.stringify(obj) :

function objToString (obj) {
    var tabjson=[];
    for (var p in obj) {
        if (obj.hasOwnProperty(p)) {
            tabjson.push('"'+p +'"'+ ':' + obj[p]);
        }
    }  tabjson.push()
    return '{'+tabjson.join(',')+'}';
}

Answer 20

If you only care about strings, objects, and arrays:

function objectToString (obj) {
        var str = '';
        var i=0;
        for (var key in obj) {
            if (obj.hasOwnProperty(key)) {
                if(typeof obj[key] == 'object')
                {
                    if(obj[key] instanceof Array)
                    {
                        str+= key + ' : [ ';
                        for(var j=0;j<obj[key].length;j++)
                        {
                            if(typeof obj[key][j]=='object') {
                                str += '{' + objectToString(obj[key][j]) + (j > 0 ? ',' : '') + '}';
                            }
                            else
                            {
                                str += '\'' + obj[key][j] + '\'' + (j > 0 ? ',' : ''); //non objects would be represented as strings
                            }
                        }
                        str+= ']' + (i > 0 ? ',' : '')
                    }
                    else
                    {
                        str += key + ' : { ' + objectToString(obj[key]) + '} ' + (i > 0 ? ',' : '');
                    }
                }
                else {
                    str +=key + ':\'' + obj[key] + '\'' + (i > 0 ? ',' : '');
                }
                i++;
            }
        }
        return str;
    }

Answer 21

maybe you are looking for

JSON.stringify(JSON.stringify(obj))


"{\"id\":30}"

Answer 22

Take a look at the jQuery-JSON plugin

At its core, it uses JSON.stringify but falls back to its own parser if the browser doesn't implement it.

Answer 23

If you can use lodash you can do it this way:

> var o = {a:1, b:2};
> '{' + _.map(o, (value, key) => key + ':' + value).join(', ') + '}'
'{a:1, b:2}'

With lodash map() you can iterate over Objects as well. This maps every key/value entry to its string representation:

> _.map(o, (value, key) => key + ':' + value)
[ 'a:1', 'b:2' ]

And join() put the array entries together.

If you can use ES6 Template String, this works also:

> `{${_.map(o, (value, key) => `${key}:${value}`).join(', ')}}`
'{a:1, b:2}'

Please note this do not goes recursive through the Object:

> var o = {a:1, b:{c:2}}
> _.map(o, (value, key) => `${key}:${value}`)
[ 'a:1', 'b:[object Object]' ]

Like node's util.inspect() will do:

> util.inspect(o)
'{ a: 1, b: { c: 2 } }'

Answer 24

function objToString (obj) {
    var str = '{';
    if(typeof obj=='object')
      {

        for (var p in obj) {
          if (obj.hasOwnProperty(p)) {
              str += p + ':' + objToString (obj[p]) + ',';
          }
      }
    }
      else
      {
         if(typeof obj=='string')
          {
            return '"'+obj+'"';
          }
          else
          {
            return obj+'';
          }
      }



    return str.substring(0,str.length-1)+"}";
}

Answer 25

var o = {a:1, b:2};

o.toString=function(){
  return 'a='+this.a+', b='+this.b;
};

console.log(o);
console.log('Item: ' + o);

Since Javascript v1.0 works everywhere (even IE) this is a native approach and allows for a very costomised look of your object while debugging and in production https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/toString

Usefull example

var Ship=function(n,x,y){
  this.name = n;
  this.x = x;
  this.y = y;
};
Ship.prototype.toString=function(){
  return '"'+this.name+'" located at: x:'+this.x+' y:'+this.y;
};

alert([new Ship('Star Destroyer', 50.001, 53.201),
new Ship('Millennium Falcon', 123.987, 287.543),
new Ship('TIE fighter', 83.060, 102.523)].join('\n'));//now they can battle!
//"Star Destroyer" located at: x:50.001 y:53.201
//"Millennium Falcon" located at: x:123.987 y:287.543
//"TIE fighter" located at: x:83.06 y:102.523

Also, as a bonus

function ISO8601Date(){
  return this.getFullYear()+'-'+(this.getMonth()+1)+'-'+this.getDate();
}
var d=new Date();
d.toString=ISO8601Date;//demonstrates altering native object behaviour
alert(d);
//IE6   Fri Jul 29 04:21:26 UTC+1200 2016
//FF&GC Fri Jul 29 2016 04:21:26 GMT+1200 (New Zealand Standard Time)
//d.toString=ISO8601Date; 2016-7-29

Answer 26

Circular References

By using below replacer we can produce less redundant JSON - if source object contains multi-references to some object, or contains circular references - then we reference it by special path-string (similar to JSONPath) - we use it as follows

let s = JSON.stringify(obj, refReplacer());

function refReplacer() {
  let m = new Map(), v= new Map(), init = null;

  return function(field, value) {
    let p= m.get(this) + (Array.isArray(this) ? `[${field}]` : '.' + field); 
    let isComplex= value===Object(value)
    
    if (isComplex) m.set(value, p);  
    
    let pp = v.get(value)||'';
    let path = p.replace(/undefined\.\.?/,'');
    let val = pp ? `#REF:${pp[0]=='[' ? '$':'$.'}${pp}` : value;
    
    !init ? (init=value) : (val===init ? val="#REF:$" : 0);
    if(!pp && isComplex) v.set(value, path);
   
    return val;
  }
}




// ---------------
// TEST
// ---------------

// gen obj with duplicate references
let a = { a1: 1, a2: 2 };
let b = { b1: 3, b2: "4" };
let obj = { o1: { o2:  a  }, b, a }; // duplicate reference
a.a3 = [1,2,b];                      // circular reference
b.b3 = a;                            // circular reference


let s = JSON.stringify(obj, refReplacer(), 4);

console.log(s);

BONUS: and here is inverse function of such serialisation

function parseRefJSON(json) {
  let objToPath = new Map();
  let pathToObj = new Map();
  let o = JSON.parse(json);
  
  let traverse = (parent, field) => {
    let obj = parent;
    let path = '#REF:$';

    if (field !== undefined) {
      obj = parent[field];
      path = objToPath.get(parent) + (Array.isArray(parent) ? `[${field}]` : `${field?'.'+field:''}`);
    }

    objToPath.set(obj, path);
    pathToObj.set(path, obj);
    
    let ref = pathToObj.get(obj);
    if (ref) parent[field] = ref;

    for (let f in obj) if (obj === Object(obj)) traverse(obj, f);
  }
  
  traverse(o);
  return o;
}



// ------------
// TEST
// ------------

let s = `{
    "o1": {
        "o2": {
            "a1": 1,
            "a2": 2,
            "a3": [
                1,
                2,
                {
                    "b1": 3,
                    "b2": "4",
                    "b3": "#REF:$.o1.o2"
                }
            ]
        }
    },
    "b": "#REF:$.o1.o2.a3[2]",
    "a": "#REF:$.o1.o2"
}`;

console.log('Open Chrome console to see nested fields:');
let obj = parseRefJSON(s);

console.log(obj);

Answer 27

/*
    This function is as JSON.Stringify (but if you has not in your js-engine you can use this)
    Params:
        obj - your object
        inc_ident - can be " " or "\t".
        show_types - show types of object or not
        ident - need for recoursion but you can not set this parameter.
*/
function getAsText(obj, inc_ident, show_types, ident) {
    var res = "";
    if (!ident)
        ident = "";
    if (typeof(obj) == "string") {
        res += "\"" + obj + "\" ";
        res += (show_types == true) ? "/* typeobj: " + typeof(obj) + "*/" : "";
    } else if (typeof(obj) == "number" || typeof(obj) == "boolean") {
        res += obj;
        res += (show_types == true) ? "/* typeobj: " + typeof(obj) + "*/" : "";
    } else if (obj instanceof Array) {
        res += "[ ";
        res += show_types ? "/* typeobj: " + typeof(obj) + "*/" : "";
        res += "\r\n";
        var new_ident = ident + inc_ident;
        var arr = [];
        for(var key in obj) {
            arr.push(new_ident + getAsText(obj[key], inc_ident, show_types, new_ident));
        } 
        res += arr.join(",\r\n") + "\r\n";
        res += ident + "]";
    } else {
        var new_ident = ident + inc_ident;      
        res += "{ ";
        res += (show_types == true) ? "/* typeobj: " + typeof(obj) + "*/" : "";
        res += "\r\n";
        var arr = [];
        for(var key in obj) {
            arr.push(new_ident + '"' + key + "\" : " + getAsText(obj[key], inc_ident, show_types, new_ident));
        }
        res += arr.join(",\r\n") + "\r\n";
        res += ident + "}\r\n";
    } 
    return res;
};

example to use:

var obj = {
    str : "hello",
    arr : ["1", "2", "3", 4],
b : true,
    vobj : {
        str : "hello2"
    }
}

var ForReading = 1, ForWriting = 2;
var fso = new ActiveXObject("Scripting.FileSystemObject")
f1 = fso.OpenTextFile("your_object1.txt", ForWriting, true)
f1.Write(getAsText(obj, "\t"));
f1.Close();

f2 = fso.OpenTextFile("your_object2.txt", ForWriting, true)
f2.Write(getAsText(obj, "\t", true));
f2.Close();

your_object1.txt:

{ 
    "str" : "hello" ,
    "arr" : [ 
        "1" ,
        "2" ,
        "3" ,
        4
    ],
    "b" : true,
    "vobj" : { 
        "str" : "hello2" 
    }

}

your_object2.txt:

{ /* typeobj: object*/
    "str" : "hello" /* typeobj: string*/,
    "arr" : [ /* typeobj: object*/
        "1" /* typeobj: string*/,
        "2" /* typeobj: string*/,
        "3" /* typeobj: string*/,
        4/* typeobj: number*/
    ],
    "b" : true/* typeobj: boolean*/,
    "vobj" : { /* typeobj: object*/
        "str" : "hello2" /* typeobj: string*/
    }

}

Answer 28

For your example, I think console.log("Item:",o) would be easiest. But, console.log("Item:" + o.toString) would also work.

Using method number one uses a nice dropdown in the console, so a long object would work nicely.

Answer 29

I hope this example will help for all those who all are working on array of objects

var data_array = [{
                    "id": "0",
                    "store": "ABC"
                },{
                    "id":"1",
                    "store":"XYZ"
                }];
console.log(String(data_array[1]["id"]+data_array[1]["store"]));

Answer 30

If you wont aplay join() to Object.

const obj = {one:1, two:2, three:3};
let arr = [];
for(let p in obj)
    arr.push(obj[p]);
const str = arr.join(',');

Answer 31

I had need to make a more configurable version of JSON.stringify as I had to add comments and know the JSON path:

const someObj = {
  a: {
    nested: {
      value: 'apple',
    },
    sibling: 'peanut'
  },
  b: {
    languages: ['en', 'de', 'fr'],
    c: {
      nice: 'heh'
    }
  },
  c: 'butter',
  d: function () {}
};

function* objIter(obj, indent = '  ', depth = 0, path = '') {
  const t = indent.repeat(depth);
  const t1 = indent.repeat(depth + 1);
  const v = v => JSON.stringify(v);
  yield { type: Array.isArray(obj) ? 'OPEN_ARR' : 'OPEN_OBJ', indent, depth };
  const keys = Object.keys(obj);
  
  for (let i = 0, l = keys.length; i < l; i++) {
    const key = keys[i];
    const prop = obj[key];
    const nextPath = !path && key || `${path}.${key}`;
 
    if (typeof prop !== 'object') {
      yield { type:  isNaN(key) ? 'VAL' : 'ARR_VAL', key, prop, indent, depth, path: nextPath };
    } else {
      yield { type: 'OBJ_KEY', key, indent, depth, path: nextPath };
      yield* objIter(prop, indent, depth + 1, nextPath);
    }
  }

  yield { type: Array.isArray(obj) ? 'CLOSE_ARR' : 'CLOSE_OBJ', indent, depth };
}

const iterMap = (it, mapFn) => {
  const arr = [];
  for (const x of it) { arr.push(mapFn(x)) }
  return arr;
}

const objToStr = obj => iterMap(objIter(obj), ({ type, key, prop, indent, depth, path }) => {
  const t = indent.repeat(depth);
  const t1 = indent.repeat(depth + 1);
  const v = v => JSON.stringify(v);

  switch (type) {
    case 'OPEN_ARR':
      return '[\n';
    case 'OPEN_OBJ':
      return '{\n';
    case 'VAL':
      return `${t1}// ${path}\n${t1}${v(key)}: ${v(prop)},\n`;
    case 'ARR_VAL':
      return `${t1}// ${path}\n${t1}${v(prop)},\n`;
    case 'OBJ_KEY':
      return `${t1}// ${path}\n${t1}${v(key)}: `;
    case 'CLOSE_ARR':
    case 'CLOSE_OBJ':
      return `${t}${type === 'CLOSE_ARR' ? ']' : '}'}${depth ? ',' : ';'}\n`;
    default:
      throw new Error('Unknown type:', type);
  }
}).join('');

const s = objToStr(someObj);
console.log(s);

Answer 32

add on ---

JSON.stringify(obj) is nice, but it will convert to json string object. sometimes we will need the string of it, like when posting it in body for WCF http post and recieving as a string.

in order of this we should reuse the stringify() as following:

let obj = {id:1, name:'cherry'};
let jsonObj = JSON.stringify(doc); //json object string
let strObj = JSON.stringify(jsonObj); //json object string wrapped with string

Answer 33

Some simple solution is the one below.

It only displays "" for strings, not for numbers and functions/methods (if the methods are written as shown here):

  let obj = {
        name: "Philips TV",
        price: 2500,
        somemethod: function() {return "Hi there"}
  };
  
  let readableobj = '{ ';
  
  for(key in obj) {
    readableobj +=
    (typeof obj[key] === "string")? `${key}: "${obj[key]}", ` : `${key}: ${obj[key]}, `;
  }
 
  readableobj += '}';
  
  console.log('obj', readableobj); // obj { name: "Philips TV", price: 42, somemethod: function() {return "Hi there"}, }

This solution uses trailing commas (which are legal since ECMAScript 5 - see reference here in MDN.)

The code is based on simplest form of a 'for in' loop:

let obj = {key: "value"};
for(key in obj) {
    return "The property " + key + " with value " + obj[key];
}

Note: It even works for this kind of method notation:

  let obj = {
        name: "Philips TV",
        price: 2500,
        somemethod() {return "Hi there"}
  };

displaying the result as

    obj { name: "Philips TV", price: 42, somemethod: somemethod() {return "Hi there"}, } 

and even for arrow function notation

  let obj = {
        name: "Philips TV",
        price: 2500,
        somemethod: () => {return "Hi there"}
  };

displaying the result as

    obj { name: "Philips TV", price: 42, somemethod: () => {return "Hi there"}, }

Therefore, you could display in an acceptable format even an object having inside it all three forms of method notations, like this one:

  let obj = {
        name: "Philips TV",
        price: 2500,
        method1: function() {return "Hi there"},
        method2() {return "Hi there"},
        method3: () => {return "Hi there"}
  };

One might see that even the second format method2() {return "Hi there"} is also eventually displayed as a pair key: value as well, by duplicating its identifier

// method2: method2() {return "Hi there"}

Finally, true / false, undefined, null are treated in the same way as numbers and functions (with no "" shown in the final format) because they are not strings, either.

IMPORTANT:

JSON.stringify() destroys the original object in the meaning that the methods are lost and not shown in the final string created by it.

Therefore we probably shouldn't accept solutions involving its use.

console.log('obj', JSON.stringify(obj)); // obj {"name":"Philips TV","price":2500} // which is NOT acceptable

Answer 34

A modified approach using reduce that let to change the separator sep between (key,value) tuple while checking last item:

/**
     * Object to string
     * @param {*} obj 
     * @param {*} k_sep keys separator
     * @param {*} v_sep values separator
     * @returns 
     */
    var objectToString: function (obj, k_sep = '=', v_sep = ',') {
      const entries = Object.entries(obj);
      return entries.reduce((str, [p, val], counter) => {
        if (counter < entries.length - 1) {
          return `${str}${p}${k_sep}${val}${v_sep}`;
        } else {
          return `${str}${p}${k_sep}${val}`;
        }
      }, '');
    }

/**
 * Object to string
 * @param {*} obj 
 * @param {*} k_sep keys separator
 * @param {*} v_sep values separator
 * @returns 
 */
var objectToString = function(obj, k_sep = '=', v_sep = ',') {
  const entries = Object.entries(obj);
  return entries.reduce((str, [p, val], counter) => {
    if (counter < entries.length - 1) {
      return `${str}${p}${k_sep}${val}${v_sep}`;
    } else {
      return `${str}${p}${k_sep}${val}`;
    }
  }, '');
}

console.log(
  objectToString({
    status_code: 200,
    execute_time: 0.1,
    ip: '1270.0.0.1'
  }, ':', ","))
console.log(
  objectToString({
    status_code: 200,
    execute_time: 0.1,
    ip: '1270.0.0.1'
  }, '=', ","))

Answer 35

I used for in and template literal to have both key-value pairs in string and it worked for me.

let obj = {
  name: "John",
  age: 22,
  isDev: true,
};
let toStr = "";
for (let key in obj) {
  if (obj.hasOwnProperty(key)) {
    toStr += `${key} ${obj[key]}` + ", ";
  }
}
console.log(toStr);
console.log(typeof toStr);

Answer 36

If you want a minimalist method of converting a variable to a string for an inline expression type situation, ''+variablename is the best I have golfed.

If 'variablename' is an object and you use the empty string concatenation operation, it will give the annoying [object Object], in which case you probably want Gary C.'s enormously upvoted JSON.stringify answer to the posted question, which you can read about on Mozilla's Developer Network at the link in that answer at the top.

Answer 37

If you are using the Dojo javascript framework then there is already a build in function to do this: dojo.toJson() which would be used like so.

var obj = {
  name: 'myObj'
};
dojo.toJson(obj);

which will return a string. If you want to convert the object to json data then add a second parameter of true.

dojo.toJson(obj, true);

http://dojotoolkit.org/reference-guide/dojo/toJson.html#dojo-tojson

Answer 38

This is in Angular 15:

registerForm = new FormGroup({
  fname1: new FormControl(""),
  lname1: new FormControl(""),
  address1: new FormControl(""),
  address2: new FormControl(""),
  city1: new FormControl(""),
  state1: new FormControl(""),
  zip1: new FormControl("")

});

registerSubmited() {
alert(this.registerForm.value.fname1);
alert(this.registerForm.value.lname1);
alert(this.registerForm.value.address1);
alert(this.registerForm.value.address2);
alert(this.registerForm.value.city1);
alert(this.registerForm.value.state1);
alert(this.registerForm.value.zip1);
}

Answer 39

The JavaScript exception "cyclic object value" occurs when object references were found in JSON. JSON.stringify() doesn't try to solve them and fails accordingly.

JSON.stringify can fail in some conditions: What went wrong?

The JSON format per se doesn't support object references (although an IETF draft exists), hence JSON.stringify() doesn't try to solve them and fails accordingly:

TypeError: cyclic object value (Firefox) TypeError: Converting

circular structure to JSON (Chrome and Opera) TypeError: Circular

reference in value argument not supported (Edge)

Solution from the spec author of the JSON data format

/* JSON.decycle 
https://github.com/douglascrockford/JSON-js/blob/master/cycle.js
*/
if(typeof JSON.decycle!=="function"){JSON.decycle=function decycle(object,replacer){"use strict";var objects=new WeakMap();return(function derez(value,path){var old_path;var nu;if(replacer!==undefined){value=replacer(value)}
if(typeof value==="object"&&value!==null&&!(value instanceof Boolean)&&!(value instanceof Date)&&!(value instanceof Number)&&!(value instanceof RegExp)&&!(value instanceof String)){old_path=objects.get(value);if(old_path!==undefined){return{$ref:old_path}}
objects.set(value,path);if(Array.isArray(value)){nu=[];value.forEach(function(element,i){nu[i]=derez(element,path+"["+i+"]")})}else{nu={};Object.keys(value).forEach(function(name){nu[name]=derez(value[name],path+"["+JSON.stringify(name)+"]")})}
return nu}
return value}(object,"$"))}}


console.log(JSON.stringify(JSON.decycle(document))) 

Answer 40

setobjToString:function(obj){
        var me =this;
        obj=obj[0];
        var tabjson=[];
        for (var p in obj) {
            if (obj.hasOwnProperty(p)) {
                if (obj[p] instanceof Array){
                    tabjson.push('"'+p +'"'+ ':' + me.setobjToString(obj[p]));
                }else{
                    tabjson.push('"'+p +'"'+':"'+obj[p]+'"');
                }
            }
        }  tabjson.push()
        return '{'+tabjson.join(',')+'}';
    }

Answer 41

If all you want is to simply get a string output, then this should work: String(object)

Answer 42

If the object is a jQuery object, then you should use:

obj.html()

instead of:

JSON.stringify(obj)

Example:

var tr = $('tr')

console.log('This does not work:')
console.log(JSON.stringify(tr))
console.log('But this does:')
console.log(tr.html())

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<table>
<tr><td>a</td><td>b</td>
</table>