How can I show any object as string in JavaScript?

Question

If I have any object, maybe new MyObject(), and I wnat show all inner properties. How can I do it?

When use alert(new MyObject()) the result is [object Object]. But I want all inner properties. For example...

var MyObject = function() {
    this.prop1 = "Hello World";
    this.prop2 = "LOL";
    this.recursive = this;
    this.func = function() { return "func return"; }
}
alert(new MyObject());

In this case how can I do to show { prop1 = "Hello World", prop2 = "LOL", etc... }

Normally you use `JSON.stringify(new MyObject())`. Just note it will not work because of the circular referencing `this.recursive = this`, because it would print forever. To remedy that you can use the second paramater, see [this answer](http://stackoverflow.com/a/9653082/3149020). — Spencer Wieczorek, Aug 03 '16 at 03:49
@Spencer just noticed :) still I believe `stringify` accepts a callback to handle this if necessary. — Damon, Aug 03 '16 at 03:50
@Damon Yes it does, you can use the second parameter as a replacer to find circular references. I gave the solution to that in my comment above. — Spencer Wieczorek, Aug 03 '16 at 03:53
JSON.stringify raise Uncaught TypeError: Converting circular structure to JSON — Sergio Cabral, Aug 03 '16 at 03:56
@SergioCabral Read the comments above. I already explained that exactly, and gave a link to the solution. — Spencer Wieczorek, Aug 03 '16 at 03:59
Keep in mind that since this is your own object, you can feel free to override the `toString()` method. Then your `alert()` will work as written. — Josiah Keller, Aug 03 '16 at 04:09

Sergio Cabral · Answer 1 · 2021-07-01T04:01:11.737

You can write this function and convert any object to string.

Look JSFiddle

////For NodeJS remove comment below:
//var window = { };

function ToString(obj) {
    clearTimeout(window.ToStringTimeout);

    var result;
    var ident = arguments.length >= 2 ? arguments[1] : undefined;

    if (obj == null) {
        result = String(obj);
    }

    var objString;
    try {
        objString = obj.toString();
    } catch (err1) {
        try {
            objString = String(obj); 
        } catch (err2) {
            try {
                objString = obj + "";
            } catch (err3) {
                objString = "ERROR CONVERT STRING";
            }
        }
    }

    if (!result) {
        window.ToStringRecursive = window.ToStringRecursive ? window.ToStringRecursive : [];
        if (window.ToStringRecursive.indexOf(obj) >= 0) {
            result = obj ? (typeof(obj) == "string" ? "\"" + obj + "\"" : objString) : obj;
        } else {
            window.ToStringRecursive.push(obj);
        }
        if (!result) {
            switch (typeof obj) {
                case "string":
                    result = '"' + obj + '"';
                    break;
                case "function":
                    result = obj.name || objString;
                    break;
                case "object":
                    var indent = Array(ident || 1).join('\t'),
                        isArray = Array.isArray(obj);
                    result = '{[' [+isArray] + Object.keys(obj).map(
                        function(key) {
                            return '\n\t' + indent + key + ': ' + ToString(obj[key], (ident || 1) + 1);
                        }).join(',') + '\n' + indent + '}]' [+isArray];
                    break;
                default:
                    result = objString;
                    break;
            }
        }
    }

    window.ToStringTimeout = setTimeout(function() {
        delete window.ToStringTimeout;
        delete window.ToStringRecursive;
    }, 100);

    return result;
}

And use this:

console.log(ToString(new MyObject()));

To show this:

{
    prop1: "Hello World",
    prop2: "LOL",
    recursive: [object Object],
    func: function () { return "func return"; }
}

Observe... when any property is recursive this not show again, because this is infinite.

score 2 · Answer 2 · edited Aug 03 '16 at 05:45

2

Use This :

 var MyObject = function() {
     this.prop1 = "Hello World";
     this.prop2 = "LOL";
     this.recursive = this;
     this.func = function() { return "func return"; } }

 console.log(eval(new MyObject()));

Result is :

{ prop1: 'Hello World',
  prop2: 'LOL',
  recursive: [Circular],
  func: [Function] }

edited Aug 03 '16 at 05:45

Spencer Wieczorek

21,229
7
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answered Aug 03 '16 at 05:29

Meena

97
2

1

Is not string, ok? – Sergio Cabral Aug 03 '16 at 05:55

Ronnie Royston · Answer 3 · 2016-08-03T04:05:00.740

0

Like this:

var obj = {type:"Fiat", model:"500", color:"white"};
var str = '';
    
for (var p in obj) {
  str = str + p + " = " + obj[p] + ',';
}
console.log(str);

edited Aug 03 '16 at 04:05

answered Aug 03 '16 at 03:48

Ronnie Royston

16,778
6
77
91

That's not what the OP is wanting. – Spencer Wieczorek Aug 03 '16 at 03:49
umm, true. how about that? – Ronnie Royston Aug 03 '16 at 03:51
fixed it. ...ambien. – Ronnie Royston Aug 03 '16 at 04:05
i see. it runs fine for me. https://jsfiddle.net/rhroyston/v71y0emo/1/ – Ronnie Royston Aug 03 '16 at 05:23

score 0 · Answer 4 · answered Aug 03 '16 at 05:13

0

var MyObject = function() {
  this.prop1 = "Hello World";
  this.prop2 = "LOL";
  this.recursive = this;
  this.func = function() {
    return this.recursive.prop1 + "," + this.recursive.prop2;
  }
}
var output = new MyObject();
alert(output.func());

answered Aug 03 '16 at 05:13

Jaydeep Mor

1,690
3
21
39

Yes he want to get object value.Hence i create instance and call function for get value. – Jaydeep Mor Aug 03 '16 at 05:32
1

No they want to print it as an object literal. – Spencer Wieczorek Aug 03 '16 at 05:44

score 0 · Accepted Answer · answered Aug 11 '21 at 08:49

Much more efficient... using JSON.stringify with a replacer to evict recursive property:

function toString(instance, space = '  ') {
  const objects = [];
  const replacer = (key, value) => {
    if (typeof value === 'object' && value !== null) {
      if (objects.findIndex(object => object === value) >= 0) {
        return ({}).toString();
      }
      objects.push(value);
    }
    return value;
  };
  return JSON.stringify(instance, replacer, space);
}

How can I show any object as string in JavaScript?

5 Answers5