clojurescript/reagent for function doesn't work

Question

Im recently using reagent and re-frame for my clojurescript project and i have a problem: So i have html custom tags

<question id="1"></question>
<question id="2"></question>

And i want to swap them into my reagent-generated html using cljs for function

(defn mypanel []
 [:p "Hi!"])

(let [q (.getElementsByTagName js/document "question")]
  (for [i (range 2)]
    ^{:keys i}
    (reagent/render [mypanel]
                  (aget (.getElementsByTagName js/document "question") i))))

But it doesn't work, i tried to test it without using the for function by

(reagent/render [mypanel]
     (aget (.getElementsByTagName js/document "question") 0))

and it worked just fine with only one tag.

And i don't know why the for function doesn't work, or does reagent doesn't work that way? Anybody have a suggestion?

I'm very noob at this.

score 7 · Answer 1 · edited Jun 12 '16 at 22:21

7

for produces a lazy sequence, which means that none of the work to evaluate the sequence is done until it is required. You can't use lazy sequences to force side effects, as they will never be evaluated (render is one such place). To force side effects you should probably replace it with doseq. And in your case dotimes would probably be better:

(let [q (.getElementsByTagName js/document "question")]
  (dotimes [i 2]
    ^{:keys i}
    (reagent/render [mypanel]
                  (aget (.getElementsByTagName js/document "question") i))))

edited Jun 12 '16 at 22:21

Daniel Compton

13,878
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answered Jun 02 '16 at 12:34

leetwinski

17,408
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1

It worked! i see, so render have that side effects! Thanks a lot! – Nyoman Arie Pranasakti Jun 02 '16 at 13:01

score 0 · Answer 2 · answered Feb 11 '20 at 20:22

0

The other option could be to force the lazyseq returned by for:

 (doall (for [i (range 2)]....

answered Feb 11 '20 at 20:22

aarkerio

2,183
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clojurescript/reagent for function doesn't work

2 Answers2