tl;dr

1. In ECMAScript 5, it is not possible.
2. In ECMAScript 2015, it is possible with Maps.
3. In ECMAScript 2017, it would be readily available.

ECMAScript 5:

No, its not possible with objects.

You should either iterate with for..in, or Object.keys, like this

for (var key in dictionary) {
    // check if the property/key is defined in the object itself, not in parent
    if (dictionary.hasOwnProperty(key)) {           
        console.log(key, dictionary[key]);
    }
}

Note: The if condition above is necessary, only if you want to iterate the properties which are dictionary object's very own. Because for..in will iterate through all the inherited enumerable properties.

Or

Object.keys(dictionary).forEach(function(key) {
    console.log(key, dictionary[key]);
});

ECMAScript 2015

In ECMAScript 2015, you can use Map objects and iterate them with Map.prototype.entries. Quoting example from that page,

var myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

var mapIter = myMap.entries();

console.log(mapIter.next().value); // ["0", "foo"]
console.log(mapIter.next().value); // [1, "bar"]
console.log(mapIter.next().value); // [Object, "baz"]

Or iterate with for..of, like this

'use strict';

var myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

for (const entry of myMap.entries()) {
  console.log(entry);
}

Output

[ '0', 'foo' ]
[ 1, 'bar' ]
[ {}, 'baz' ]

Or

for (const [key, value] of myMap.entries()) {
  console.log(key, value);
}

Output

0 foo
1 bar
{} baz

ECMAScript 2017

ECMAScript 2017 would introduce a new function Object.entries. You can use this to iterate the object as you wanted.

'use strict';

const object = {'a': 1, 'b': 2, 'c' : 3};
for (const [key, value] of Object.entries(object)) {
  console.log(key, value);
}

Output

a 1
b 2
c 3

The Object.entries() method has been specified in ES2017 (and is supported in all modern browsers):

for (const [ key, value ] of Object.entries(dictionary)) {
    // do something with `key` and `value`
}

Explanation:

• Object.entries() takes an object like { a: 1, b: 2, c: 3 } and turns it into an array of key-value pairs: [ [ 'a', 1 ], [ 'b', 2 ], [ 'c', 3 ] ].

• With for ... of we can loop over the entries of the so created array.

• Since we are guaranteed that each of the so iterated array items is itself a two-entry array, we can use destructuring to directly assign variables key and value to its first and second item.

I think the fast and easy way is

Object.entries(event).forEach(k => {
    console.log("properties ... ", k[0], k[1]); });

just check the documentation https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries

using swagger-ui.js

you can do this -

_.forEach({ 'a': 1, 'b': 2 }, function(n, key) {
    console.log(n, key);
 });

As an improvement to the accepted answer, in order to reduce nesting, you could do this instead:

for (var key in dictionary) {
    if (!dictionary.hasOwnProperty(key)) {           
        continue;
    }
    console.log(key, dictionary[key]);
}

You can use below script.

var obj={1:"a",2:"b",c:"3"};
for (var x=Object.keys(obj),i=0;i<x.length,key=x[i],value=obj[key];i++){
    console.log(key,value);
}

outputs
1 a
2 b
c 3

Try this:

dict = {0:{1:'a'}, 1:{2:'b'}, 2:{3:'c'}}
for (var key in dict){
  console.log( key, dict[key] );
}

0 Object { 1="a"}
1 Object { 2="b"}
2 Object { 3="c"}

Try this:

var value;
for (var key in dictionary) {
    value = dictionary[key];
    // your code here...
}

You can do something like this :

dictionary = {'ab': {object}, 'cd':{object}, 'ef':{object}}
var keys = Object.keys(dictionary);

for(var i = 0; i < keys.length;i++){
   //keys[i] for key
   //dictionary[keys[i]] for the value
}

WELCOME TO 2020 *Drools in ES6*

Theres some pretty old answers in here - take advantage of destructuring. In my opinion this is without a doubt the nicest (very readable) way to iterate an object.

Object.entries(myObject).forEach(([k,v]) => {
    console.log("The key: ",k)
    console.log("The value: ",v)
})