Use native JSON.stringify method. Works with nested objects and all major browsers support this method.
str = JSON.stringify(obj);
str = JSON.stringify(obj, null, 4); // (Optional) beautiful indented output.
console.log(str); // Logs output to dev tools console.
alert(str); // Displays output using window.alert()
Link to Mozilla API Reference and other examples.
obj = JSON.parse(str); // Reverses above operation (Just in case if needed.)
Use a custom JSON.stringify replacer if you encounter this Javascript error
"Uncaught TypeError: Converting circular structure to JSON"How to display a JavaScript object?
If you want to print the object for debugging purposes, use the code:
var obj = {
prop1: 'prop1Value',
prop2: 'prop2Value',
child: {
childProp1: 'childProp1Value',
},
}
console.log(obj)
will display:
Note: you must only log the object. For example, this won’t work:
console.log('My object : ' + obj)
Note ‘: You can also use a comma in the log method, then the first line of the output will be the string and after that, the object will be rendered:
console.log('My object: ', obj);Solution example:
var output = '';
for (var property in object) {
output += property + ': ' + object[property]+'; ';
}
alert(output);Answer #3:
console.dir(object):
Displays an interactive listing of the properties of a specified JavaScript object. This listing lets you use disclosure triangles to examine the contents of child objects.
Note that the console.dir() feature is non-standard.
Answer #4:
try this :
console.log(JSON.stringify(obj))
This will print the stringify version of object. So instead of [object] as an output you will get the content of object.
Answer #5:
If you want to use alert, to print your object, you can do this:
alert("myObject is " + myObject.toSource());
It should print each property and its corresponding value in string format.
Answer #6:
If you would like to see data in tabular format you can use
console.table(obj);
Table can be sorted if you click on the table column.
You can also select what columns to show:
console.table(obj, ['firstName', 'lastName']);How to display a JavaScript object?
Simply use
JSON.stringify(obj)
Example
var args_string = JSON.stringify(obj);
console.log(args_string);
Or
alert(args_string);
Also, note in javascript functions are considered as objects.
As an extra note :
Actually you can assign new property like this and access it console.log or display it in alert
foo.moo = "stackoverflow";
console.log(foo.moo);
alert(foo.moo);Answer #8:
Function:
var print = function(o){
var str='';
for(var p in o){
if(typeof o[p] == 'string'){
str+= p + ': ' + o[p]+'; </br>';
}else{
str+= p + ': { </br>' + print(o[p]) + '}';
}
}
return str;
}
Usage:
var myObject = {
name: 'Wilson Page',
contact: {
email: 'wilson@hotmail.com',
tel: '123456789'
}
}
$('body').append( print(myObject) );Answer #9:
NB: In these examples, yourObj defines the object you want to examine.
First off my least favorite yet most utilized way of displaying an object:
This is the defacto way of showing the contents of an object
console.log(yourObj)
will produce something like :
I think the best solution is to look through the Objects Keys, and then through the Objects Values if you really want to see what the object holds…
console.log(Object.keys(yourObj));
console.log(Object.values(yourObj));
It will output something like :
(pictured above: the keys/values stored in the object)
There is also this new option if you’re using ECMAScript 2016 or newer:
Object.keys(yourObj).forEach(e => console.log(`key=${e} value=${yourObj[e]}`));
This will produce the neat output :
The solution mentioned in a previous answer: console.log(yourObj) displays too many parameters and is not the most user friendly way to display the data you want. That is why I recommend logging keys and then values separately.
Next up :
console.table(yourObj)
Someone in an earlier comment suggested this one, however it never worked for me. If it does work for someone else on a different browser or something, then kudos! Ill still put the code here for reference! Will output something like this to the console :
Alternative answer explained:
This one is not for printing to screen (via console, or textfield or whatever). It does work fine in those situations and works just fine as the OP requested, for alert. Many answers here do not address using alert as the OP requested. Anyhow, It is, however, formatted for data transport. This version seems to return a very similar result as toSource(). I’ve not tested against JSON.stringify, but I assume this is about the same thing. This version is more like a poly-fil so that you can use it in any environment. The result of this function is a valid Javascript object declaration.
I wouldn’t doubt if something like this was already on SO somewhere, but it was just shorter to make it than to spend a while searching past answers. And since this question was my top hit on google when I started searching about this; I figured putting it here might help others.
Anyhow, the result from this function will be a string representation of your object, even if your object has embedded objects and arrays, and even if those objects or arrays have even further embedded objects and arrays. (I heard you like to drink? So, I pimped your car with a cooler. And then, I pimped your cooler with a cooler. So, your cooler can drink, while your being cool.)
Arrays are stored with [] instead of {} and thus dont have key/value pairs, just values. Like regular arrays. Therefore, they get created like arrays do.
Also, all string (including key names) are quoted, this is not necessary unless those strings have special characters (like a space or a slash). But, I didn’t feel like detecting this just to remove some quotes that would otherwise still work fine.
This resulting string can then be used with eval or just dumping it into a var thru string manipulation. Thus, re-creating your object again, from the text.
function ObjToSource(o){
if (!o) return 'null';
var k="",na=typeof(o.length)=="undefined"?1:0,str="";
for(var p in o){
if (na) k = "'"+p+ "':";
if (typeof o[p] == "string") str += k + "'" + o[p]+"',";
else if (typeof o[p] == "object") str += k + ObjToSource(o[p])+",";
else str += k + o[p] + ",";
}
if (na) return "{"+str.slice(0,-1)+"}";
else return "["+str.slice(0,-1)+"]";
}
Let me know if I messed it all up, works fine in my testing. Also, the only way I could think of to detect type array was to check for the presence of length. Because Javascript really stores arrays as objects, I cant actually check for type array (there is no such type!). If anyone else knows a better way, I would love to hear it. Because, if your object also has a property named length then this function will mistakenly treat it as an array.
EDIT: Below is the fixed function to be able to print infinitely recursive objects. This does not print the same as toSource from FF because toSource will print the infinite recursion one time, whereas, this function will kill it immediately. This function runs slower than the one above, so I’m adding it here instead of editing the above function, as it’s only needed if you plan to pass objects that link back to themselves, somewhere.
const ObjToSource=(o)=> {
if (!o) return null;
let str="",na=0,k,p;
if (typeof(o) == "object") {
if (!ObjToSource.check) ObjToSource.check = new Array();
for (k=ObjToSource.check.length;na<k;na++) if (ObjToSource.check[na]==o) return '{}';
ObjToSource.check.push(o);
}
k="",na=typeof(o.length)=="undefined"?1:0;
for(p in o){
if (na) k = "'"+p+"':";
if (typeof o[p] == "string") str += k+"'"+o[p]+"',";
else if (typeof o[p] == "object") str += k+ObjToSource(o[p])+",";
else str += k+o[p]+",";
}
if (typeof(o) == "object") ObjToSource.check.pop();
if (na) return "{"+str.slice(0,-1)+"}";
else return "["+str.slice(0,-1)+"]";
}
Test:
var test1 = new Object();
test1.foo = 1;
test1.bar = 2;
var testobject = new Object();
testobject.run = 1;
testobject.fast = null;
testobject.loop = testobject;
testobject.dup = test1;
console.log(ObjToSource(testobject));
console.log(testobject.toSource());
Result:
{'run':1,'fast':null,'loop':{},'dup':{'foo':1,'bar':2}}
({run:1, fast:null, loop:{run:1, fast:null, loop:{}, dup:{foo:1, bar:2}}, dup:{foo:1, bar:2}})
NOTE: Trying to print document.body is a terrible example. For one, FF just prints an empty object string when using toSource. And when using the function above, FF crashes on SecurityError: The operation is insecure.. And Chrome will crash on Uncaught RangeError: Maximum call stack size exceeded. Clearly, document.body was not meant to be converted to a string. Because it’s either too large, or against security policy to access certain properties. Unless I messed something up here, do tell!
Hope you learned something from this post.
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