Try this:
var keys = [];
for (var key in dictionary) {
if (dictionary.hasOwnProperty(key)) {
keys.push(key);
}
}
hasOwnProperty
is needed because it’s possible to insert keys into the prototype object of dictionary
. But you typically don’t want those keys included in your list.
For example, if you do this:
Object.prototype.c = 3;
var dictionary = {a: 1, b: 2};
and then do a for...in
loop over dictionary
, you’ll get a
and b
, but you’ll also get c
.