reframe-checkbox.cljs

;; Here we are importing re-frame.core (our SPA library and referring to it as rf for brevity)
(ns simple.core
  (:require [re-frame.core :as rf]
            [clojure.string :as str]))

;; Event Handler
(rf/reg-event-db                        ;; By calling the reg-event-db function we can register an event handler
 :change-checkbox                       ;; for when the :change-checkbox event is dispatched
 (fn [db [_ new-value]]                 ;; we then supply a function that takes the db and an event vector as 2 the 2 parameters
   (assoc db :is-checked new-value)))   ;; we update the DB map (think similar to a JS object) :is-checked value to the new value and return

;; Query 
(rf/reg-sub            ;; We register a subscription with the following key and function
 :is-checked           ;; The key is for what subscription we want to listen for
 (fn [db _]            ;; we supply a function that takes the DB atom as a parameter
   (:is-checked db)))  ;; We get the value stored from the :is-checked key

;; View (including dispatch)
(defn checkbox-input                                    ;; Define a function
  []                                                    ;; that takes no parameters
  (let [is-checked (rf/subscribe [:is-checked])]        ;; create a variable that stores the atom from the subscription to :is-checked
    [:div.checkbox                                      ;; return a vector of keys and values, that gets evalutated to HTML (think how JSX is to HTML... but better) 
     "Checkbox button is: " (str @is-checked)           ;; Dereference the atom and pull the value of the checkbox
     [:div                                              ;; Nested div
      "Change input: "
      [:input {:type "checkbox"                         ;; define an input -> <input type="checkbox" value={is-checked} on-change={() => dispatch(...) />
               :value @is-checked
               ;; We supply a function to on-change that calls dispatch with a vector containing the dispatch key and the new value
               :on-change #(rf/dispatch [:change-checkbox (not @is-checked)])}]]]))

this will also helps

(rf/dispatch [    (.. % -target -checked)])