How to get index for an item in reagent

Question

When I iterate over vector in Reagent, like this:

(for [item ["rattata" "pidgey" "spearow"]]
  [:li item])])

I would like to get index of a specific item - like this:

  [:li item index]

I'm not asking about general clojure 'for', because another way to iterate over vector will satisfy me as well.

Answer 1

This is actually a general Clojure question, rather than specific to Reagent, but there are a few way you could do this.

You can approach it similarly to your current code with something like

(def items ["rattata" "pidgey" "spearow"])
(for [index (range (count items))]
  [:li (get items index) index])

You could also use map-indexed

(doall (map-indexed (fn [index item] [:li index item]) items))

The doall in this case is for Reagent, as map and friends return lazy lists that can interfere with Reagent (it will print a warning to the console if you forget it).

Answer 2

You can also combine map-indexed with for-loop:

(for [[index item] (map-indexed vector items)]
  [:li item index])])

; vector function is a shorthand:
(for [[index item] (map-indexed (fn [index item] [index item]) items)]
  [:li item index])])