Underscore forEach index?

Question

I have an object that contains the follow structure

{
Apples: Array[1],
Mangos: Array[2],
Oranges: Array[5],
Bananas: Array[11]
}

These values are extracted using a

_.forEach(contents, function(values, key) {

}

Where the key = apples and the values would be the array. I am wondering how I can get the current index within this foreach loop ?

i.e. so I get 1,2,3,4 ? There may not be a way to do this other than to push them to an array ?

You should notice that objects are an unordered collection of properties. — CD.., Feb 27 '13 at 08:48
Since it is a hash object, I don't think it preserves the order of keys — Arun P Johny, Feb 27 '13 at 08:49
thanks for the responses - i think the easiest way is just to push the key into an array and keep track of it there due the inability to keep track ? — Andy, Feb 27 '13 at 08:50
the position within the object is not useful or meaningful. why do you think you want it? — Eevee, Feb 27 '13 at 08:51

Flavien Volken · Accepted Answer · 2013-02-27T08:53:41.760

4

I'm not sure that I completely got your question, but if you are looking for the index of the item currently enumerated here is a way using the "_forEach" equivalent

var test = {"a":"foo", "b":"bar"}
var index = 0;
for (key in test){ alert(key +"is at "+index+" position"); index++;}

edited Feb 27 '13 at 08:53

answered Feb 27 '13 at 08:46

Flavien Volken

19,196
12
100
133

shouldn't it be (index++)? – Arun P Johny Feb 27 '13 at 08:49
yes sorry =), also as you mentioned, there is no logical order convention for the keys (only arrays are doing so) – Flavien Volken Feb 27 '13 at 08:51
Even though it is not part of the standard it looks like most browsers share a common behaviour according this question http://stackoverflow.com/questions/280713/elements-order-in-a-for-in-loop – Arun P Johny Feb 27 '13 at 09:08

score 4 · Answer 2 · answered Feb 02 '18 at 13:42

Try this:

_.each(myArray,function(eachItem,index){
       console.log("item: "+ eachItem + "at index " + index);
    }

Example:

var myArr = [
Apples: "One",
Mangos: "Two",
Oranges: "Three",
Bananas: "Four"
]

_.each(myArr,function(eachItem,index){
       console.log("item: "+ eachItem + "at index " + index);
    }

Output:

item:One at index 0

item:Two at index 1

item:Three at index 2

item:Four at index 3

Reference: Underscore JS Reference Link

Underscore forEach index?

2 Answers2