How to list the properties of a JavaScript object?

Question

Say I create an object thus:

var myObject =
        {\"ircEvent\": \"PRIVMSG\", \"method\": \"newURI\", \"regex\": \"^http://.*\"};

What is

Answer 1

I'm a huge fan of the dump function.

http://ajaxian.com/archives/javascript-variable-dump-in-coldfusion

Answer 2

In modern browsers (IE9+, FF4+, Chrome5+, Opera12+, Safari5+) you can use the built in Object.keys method:

var keys = Object.keys(myObject);

The above has a full polyfill but a simplified version is:

var getKeys = function(obj){
   var keys = [];
   for(var key in obj){
      keys.push(key);
   }
   return keys;
}

Alternatively replace var getKeys with Object.prototype.keys to allow you to call .keys() on any object. Extending the prototype has some side effects and I wouldn't recommend doing it.

Answer 3

IE does not support for(i in obj) for native properties. Here is a list of all the props I could find.

It seems stackoverflow does some stupid filtering.

The list is available at the bottom of this google group post:- https://groups.google.com/group/hackvertor/browse_thread/thread/a9ba81ca642a63e0

Answer 4

Note that Object.keys and other ECMAScript 5 methods are supported by Firefox 4, Chrome 6, Safari 5, IE 9 and above.

For example:

var o = {"foo": 1, "bar": 2}; 
alert(Object.keys(o));

ECMAScript 5 compatibility table: http://kangax.github.com/es5-compat-table/

Description of new methods: http://markcaudill.com/index.php/2009/04/javascript-new-features-ecma5/

Answer 5

Since I use underscore.js in almost every project, I would use the keys function:

var obj = {name: 'gach', hello: 'world'};
console.log(_.keys(obj));

The output of that will be:

['name', 'hello']

Answer 6

With ES6 and later (ECMAScript 2015), you can get all properties like this:

let keys = Object.keys(myObject);

And if you wanna list out all values:

let values = Object.keys(myObject).map(key => myObject[key]);