Iterate over values of object

Question

I want to iterate over all values of a map. I know it's possible to iterate over all keys. But is it possible to iterate directly over the values?

 var map = { key1 : 'value1', key2 : 'value2' }
 for (var key in map) { ...} // iterates over keys

Answer 1

It's not a map. It's simply an Object.

Edit: below code is worse than OP's, as Amit pointed out in comments.

You can "iterate over the values" by actually iterating over the keys with:

var value;
Object.keys(map).forEach(function(key) {
    value = map[key];
    console.log(value);
});

Answer 2

I iterate like this and it works for me.

for (let [k, v] of myMap) {
    console.log("Key: " + k);
    console.log("Value: " + v);
}

Hope this helps :)

Answer 3

In the sense I think you intended, in ES5 or ES2015, no, not without some work on your part.

In ES2016, probably with object.values.

Mind you Arrays in JavaScript are effectively a map from an integer to a value, and the values in JavaScript arrays can be enumerated directly.

['foo', 'bar'].forEach(v => console.log(v)); // foo bar

Also, in ES2015, you can make an object iterable by placing a function on a property with the name of Symbol.iterator:

var obj = { 
    foo: '1', 
    bar: '2',
    bam: '3',
    bat: '4',
};

obj[Symbol.iterator] = iter.bind(null, obj);

function* iter(o) {
    var keys = Object.keys(o);
    for (var i=0; i<keys.length; i++) {
        yield o[keys[i]];
    }
}

for(var v of obj) { console.log(v); } // '1', '2', '3', '4'

Also, per other answers, there are other built-ins that provide the functionality you want, like Map (but not WeakMap because it is not iterable) and Set for example (but these are not present in all browsers yet).

Answer 4

EcmaScript 2017 introduced Object.entries that allows you to iterate over values and keys. Documentation

var map = { key1 : 'value1', key2 : 'value2' }

for (let [key, value] of Object.entries(map)) {
    console.log(`${key}: ${value}`);
}

The result will be:

key1: value1
key2: value2