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@@ -0,0 +1,92 @@
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+<!DOCTYPE html>
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+<html lang="en">
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+<head>
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+ <meta charset="UTF-8">
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+ <meta http-equiv="X-UA-Compatible" content="IE=edge">
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+ <meta name="viewport" content="width=device-width, initial-scale=1.0">
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+ <title>A-Level</title>
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+</head>
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+<body>
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+ <div id="assortment"></div>
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+<select id="fruits">
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+ <option value="apples">apples</option>
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+ <option value="oranges">oranges</option>
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+ <option value="bananas">bananas</option>
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+</select>
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+<input type="number" id="quantity" placeholder="quantity of goods">
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+<input type="number" id="cash" placeholder="give me your cash">
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+<button id="btn">Buy</button>
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+
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+<script>
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+ function fruitBuyer(state, {type, whatFruits, howMany, cash}){
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+ if (!state){
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+ return {
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+
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+ apples: {
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+ quantity: 100,
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+ price: 15
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+ },
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+
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+ oranges: {
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+ quantity: 100,
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+ price: 25
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+ },
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+
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+ bananas:{
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+ quantity: 100,
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+ price: 20
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+ },
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+ cashBox: 0
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+ }
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+ }
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+ if (type === 'buy'){
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+ return {
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+ ...state,
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+ [whatFruits]: {
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+ quantity: ((state[whatFruits].quantity - howMany) < 0 || cash < state[whatFruits].price ) ? state[whatFruits].quantity : state[whatFruits].quantity - howMany,
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+ price: state[whatFruits].price
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+ },
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+ cashBox: ((state[whatFruits].quantity - howMany) < 0 || cash < state[whatFruits].price ) ? state.cashBox : (cash * howMany) + state.cashBox
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+
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+ }
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+ }
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+ return state
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+
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+}
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+
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+function createStore(reducer){
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+ let state = reducer(undefined, {})
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+ let cbs = []
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+
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+ const getState = () => state
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+ const subscribe = cb => (cbs.push(cb),
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+ () => cbs = cbs.filter(c => c !== cb))
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+ const dispatch = action => {
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+ const newState = reducer(state, action)
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+ if (newState !== state){
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+ state = newState
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+ for (let cb of cbs) cb()
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+ }
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+ }
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+
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+ return {
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+ getState,
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+ dispatch,
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+ subscribe
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+ }
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+}
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+const store = createStore(fruitBuyer);
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+store.subscribe(() => assortment.innerHTML = JSON.stringify(store.getState()));
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+const buyFruits = (whatFruits, howMany, cash) => ({type: 'buy', whatFruits:`${whatFruits}`, howMany, cash});
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+btn.addEventListener('click', () =>{
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+ const whatFruits = fruits.value;
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+ const howMany = quantity.value;
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+ const cashValue = cash.value
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+ store.dispatch(buyFruits(whatFruits, howMany, cashValue))
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+})
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+store.dispatch(buyFruits('apples',0, 0));
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+
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+</script>
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+</body>
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+</html>
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+
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