{"id":3538,"date":"2022-08-09T19:41:17","date_gmt":"2022-08-09T10:41:17","guid":{"rendered":"https:\/\/dennie.tokyo\/it\/?p=3538"},"modified":"2022-08-13T12:09:51","modified_gmt":"2022-08-13T03:09:51","slug":"%e3%80%90react%e3%80%91%e3%83%95%e3%83%83%e3%82%af%e3%81%a8%e3%82%ab%e3%82%b9%e3%82%bf%e3%83%a0%e3%83%95%e3%83%83%e3%82%af","status":"publish","type":"post","link":"https:\/\/dennie.tokyo\/it\/?p=3538","title":{"rendered":"\u3010React\u3011\u30d5\u30c3\u30af\u3068\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af"},"content":{"rendered":"\n

\u524d\u56de\u306f\u30b9\u30c6\u30fc\u30c8\u3092\u4f7f\u7528\u3057\u3066\u72b6\u614b(\u30c7\u30fc\u30bf)\u3092\u7ba1\u7406\u3057\u307e\u3057\u305f\u3002<\/p>\n\n\n\n\n\n\n\n

\u524d\u56de<\/span>\n

<\/p>\n

\u3010React\u3011\u30b9\u30c6\u30fc\u30c8\u7ba1\u7406<\/a><\/p>\n<\/div>\n\n\n\n

\u30b9\u30c6\u30fc\u30c8\u306fReact\u304c\u63d0\u4f9b\u3059\u308b\u6a5f\u80fd\u3067\u3059\u3002
\u3053\u306e\u3088\u3046\u306a\u6a5f\u80fd\u306f\u30d5\u30c3\u30af\u3068\u547c\u3070\u308c\u3001\u30b9\u30c6\u30fc\u30c8\u4ee5\u5916\u306b\u3082\u5b58\u5728\u3057\u307e\u3059\u3002React\u304c\u63d0\u4f9b\u3059\u308b\u30d5\u30c3\u30af\u3092\u30d3\u30eb\u30c8\u30a4\u30f3\u30d5\u30c3\u30af\u3068\u8a00\u3044\u307e\u3059\u3002\u307e\u305f\u3001\u30d5\u30c3\u30af\u306f\u81ea\u8eab\u3067\u4f5c\u6210\u3059\u308b\u4e8b\u3082\u53ef\u80fd\u3067\u3001\u81ea\u8eab\u3067\u4f5c\u6210\u3057\u305f\u30d5\u30c3\u30af\u3092\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u3068\u8a00\u3044\u307e\u3059\u3002<\/p>\n\n\n\n

\u30d5\u30c3\u30af\u3068\u306f<\/h1>\n\n\n\n

\u30d5\u30c3\u30af\u306f\u518d\u5229\u7528\u53ef\u80fd\u306a\u6a5f\u80fd\u306e\u4e8b\u3067\u3059\u3002\u4f8b\u3048\u3070\u4eca\u307e\u3067\u4f7f\u7528\u3057\u3066\u304d\u305f\u30b9\u30c6\u30fc\u30c8\u3082\u30a4\u30f3\u30dd\u30fc\u30c8\u3059\u308b\u3060\u3051\u7c21\u5358\u306b\u5229\u7528\u3059\u308b\u4e8b\u304c\u3067\u304d\u307e\u3057\u305f\u3002<\/p>\n\n\n\n

\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u3068\u306f<\/h1>\n\n\n\n

\u5b9f\u614b<\/h2>\n\n\n\n

\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u306f\u81ea\u8eab\u3067\u4f5c\u6210\u3057\u305f\u30d5\u30c3\u30af\u306e\u4e8b\u3067\u3059\u3002\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u3068\u8a00\u3063\u3066\u3082\u5b9f\u614b\u306f\u30d5\u30c3\u30af\u3092\u4f7f\u3063\u3066\u5b9f\u88c5\u3055\u308c\u305f\u95a2\u6570\u306e\u4e8b\u3067\u3059\u3002<\/p>\n\n\n\n

\u518d\u5229\u7528\u3068\u5171\u901a\u5316<\/h2>\n\n\n\n

\u30d5\u30c3\u30af\u306f\u518d\u5229\u7528\u3092\u76ee\u7684\u3068\u3057\u3066\u3044\u307e\u3059\u3002
\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3057\u3066\u3044\u308b\u4e2d\u3067\u540c\u3058\u3088\u3046\u306a\u51e6\u7406\u3092\u66f8\u304f\u5834\u9762\u304c\u3042\u308b\u5834\u5408\u3001\u95a2\u6570\u5316(\u5171\u901a\u5316)\u3057\u3088\u3046\u3068\u601d\u3046\u3067\u3057\u3087\u3046\u3002\u540c\u3058\u51e6\u7406\u3092\u95a2\u6570\u5316\u3057\u3066\u518d\u5229\u7528\u3059\u308b\u3088\u3046\u306a\u30a4\u30e1\u30fc\u30b8\u3067\u3059\u3002
\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3084\u4f8b\u3092\u898b\u306a\u304c\u3089\u30a4\u30e1\u30fc\u30b8\u3092\u63b4\u3093\u3067\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n

\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u306e\u4f8b<\/h1>\n\n\n\n

\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u306b\u89e6\u308c\u308b\u524d\u306b\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u3092\u4f7f\u7528\u305b\u305a\u3001\u300c\u521d\u3081\u306b\u3084\u308a\u305f\u3044\u4e8b\u300d\u3068\u300c\u6b21\u306b\u3084\u308a\u305f\u3044\u4e8b\u300d\u3092\u3084\u3063\u3066\u307f\u3088\u3046\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n\n\n\n

\u521d\u3081\u306b\u3084\u308a\u305f\u3044\u4e8b<\/h2>\n\n\n\n

\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u3092\u8a2d\u5b9a\u3057\u753b\u9762\u306b\u8868\u793a\u3055\u305b\u307e\u3059\u3002\u30eb\u30fc\u30eb\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\u3002<\/p>\n\n\n\n

\u30fb\u300c\u30d7\u30e9\u30b9\u300d\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068\u3001\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u304c1\u5897\u3048\u308b\u3002\u6700\u5927\u306f3\u3002
\u30fb\u300c\u30de\u30a4\u30ca\u30b9\u300d\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068\u3001\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u304c1\u6e1b\u308b\u3002\u6700\u5c0f\u306f1\u3002
\u30fb\u300c\u30ea\u30bb\u30c3\u30c8\u300d\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068\u3001\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u304c1\u306b\u306a\u308b\u3002<\/p>\n\n\n\n

\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30a2\u30a6\u30c8\u30d7\u30c3\u30c8\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8<\/h3>\n\n\n\n

\u4eca\u56de\u306f\u3001\u4ee5\u4e0b\u306e2\u3064\u306e\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3092\u4f7f\u7528\u3057\u307e\u3059\u3002<\/p>\n\n\n\n

\u30fbApp\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8
\u30b9\u30c6\u30fc\u30c8\u306b\u3066\u30b3\u30fc\u30d2\u30fc\u6570\u91cf\u3092\u4fdd\u6301\u3059\u308b\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3002<\/p>\n\n\n\n

\u30fbOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8
\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u3092\u9078\u629e\u3067\u304d\u308b\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3002<\/p>\n\n\n\n

App\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8<\/h4>\n\n\n\n

App\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u306f\u30b9\u30c6\u30fc\u30c8\u3092\u5229\u7528\u3057\u3066\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u3092\u4fdd\u6301\u3057\u307e\u3059\u3002 Order\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3078\u30b9\u30c6\u30fc\u30c8(\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u3068\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u3092\u66f4\u65b0\u3059\u308b\u95a2\u6570)\u3092\u30d7\u30ed\u30d1\u30c6\u30a3\u7d4c\u7531\u3067\u6e21\u3057\u3066\u3044\u307e\u3059\u3002\u3053\u3053\u3089\u8fba\u306f\u7279\u5225\u65b0\u3057\u3044\u3053\u3068\u306f\u3057\u3066\u3044\u307e\u305b\u3093\u3002<\/p>\n\n\n\n

import React from 'react';\nimport Order from '.\/Order';\n\nfunction App() {\n\n  \/\/ \u9078\u629e\u3055\u308c\u305f\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u3092\u4fdd\u6301\u3059\u308b\u30b9\u30c6\u30fc\u30c8\n  const [orderVal, setOrderVal] = React.useState(1);\n  \n  \/\/ \u5b50\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3092\u547c\u3073\u51fa\u3059\n  return (\n    <>\n      <Order val={orderVal} setVal={setOrderVal} \/>\n    <\/>\n  );\n}\n\nexport default App;<\/code><\/pre><\/div>\n\n\n\n
Order\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8<\/h4>\n\n\n\n
\u30d7\u30e9\u30b9\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068incrementOrder\u95a2\u6570\u304c\u547c\u3070\u308c\u307e\u3059\u3002\u3053\u306e\u95a2\u6570\u306f\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u30921\u5897\u3084\u3057\u307e\u3059\u3002\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u304c3\u4ee5\u4e0a\u306e\u5834\u5408\u3001\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u30923\u3078\u8a2d\u5b9a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n
\u30de\u30a4\u30ca\u30b9\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068decrementOrder\u95a2\u6570\u304c\u547c\u3070\u308c\u307e\u3059\u3002\u3053\u306e\u95a2\u6570\u306f\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u30921\u6e1b\u3089\u3057\u307e\u3059\u3002\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u304c1\u4ee5\u4e0b\u306e\u5834\u5408\u3001\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u30921\u3078\u8a2d\u5b9a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n
\u30ea\u30bb\u30c3\u30c8\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068resetOrder\u95a2\u6570\u304c\u547c\u3070\u308c\u307e\u3059\u3002\u3053\u306e\u95a2\u6570\u306f\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u30921\u306b\u3057\u307e\u3059\u3002<\/p>\n\n\n\n
function Order({val, setVal}) {\n\n    \/\/ \u30b3\u30fc\u30d2\u30fc\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u5897\u3084\u3059\n    const incrementOrder = () => {\n\n        \/\/ \u30b3\u30fc\u30d2\u30fc\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u304c3\u4ee5\u4e0a\u306e\u5834\u5408\u3001\u30b3\u30fc\u30d2\u30fc\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30923\u306b\u3059\u308b\u3002\n        if(val >= 3){\n            setVal(3);\n            return;\n        }\n\n        setVal((val) => val + 1);\n    };\n\n    \/\/ \u30b3\u30fc\u30d2\u30fc\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u6e1b\u3089\u3059\n    const decrementOrder = () => {\n\n        \/\/ \u30b3\u30fc\u30d2\u30fc\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u304c1\u4ee5\u4e0b\u306e\u5834\u5408\u3001\u30b3\u30fc\u30d2\u30fc\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u306b\u3059\u308b\u3002\n        if(val <= 1){\n            setVal(1);\n            return;\n        }\n\n        setVal((val) => val - 1);\n    };\n\n    \/\/ \u30b3\u30fc\u30d2\u30fc\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u306b\u3059\u308b\n    const resetOrder = () => setVal(1);\n\n    \/\/ \u30d6\u30e9\u30a6\u30b6\u8868\u793a\u51e6\u7406\n    return (\n      <>\n        <p>\u6ce8\u6587\u3059\u308b\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u3092\u6307\u5b9a\u304f\u3060\u3055\u3044\u3002<\/p>\n        <div>\n            <button onClick={incrementOrder}>\u30d7\u30e9\u30b9<\/button>\n            <button onClick={decrementOrder}>\u30de\u30a4\u30ca\u30b9<\/button>\n            <button onClick={resetOrder}>\u30ea\u30bb\u30c3\u30c8<\/button>\n        <\/div>\n        <p>\u30b3\u30fc\u30d2\u30fc\u306e\u6570\uff1a{val}<\/p>\n      <\/>\n    );\n  }\n  \n  export default Order;<\/code><\/pre><\/div>\n\n\n\n
\u6b21\u306b\u3084\u308a\u305f\u3044\u4e8b<\/h2>\n\n\n\n
\u30b3\u30fc\u30d2\u30fc\u4ee5\u5916\u306b\u3001\u30df\u30eb\u30af\u3082\u6ce8\u6587\u3067\u304d\u3088\u3046\u306b\u3057\u307e\u3059\u3002\u30b3\u30fc\u30d2\u30fc\u306e\u6ce8\u6587\u6570\u3068\u540c\u3058\u30eb\u30fc\u30eb\u3068\u3057\u307e\u3059\u3002<\/p>\n\n\n\n
\u30fb\u300c\u30d7\u30e9\u30b9\u300d\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068\u3001\u30df\u30eb\u30af\u306e\u6570\u91cf\u304c1\u5897\u3048\u308b\u3002\u6700\u5927\u306f3\u3002
\u30fb\u300c\u30de\u30a4\u30ca\u30b9\u300d\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068\u3001\u30df\u30eb\u30af\u306e\u6570\u91cf\u304c1\u6e1b\u308b\u3002\u6700\u5c0f\u306f1\u3002
\u30fb\u300c\u30ea\u30bb\u30c3\u30c8\u300d\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068\u3001\u30df\u30eb\u30af\u306e\u6570\u91cf\u304c1\u306b\u306a\u308b\u3002<\/p>\n\n\n\n
\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30a2\u30a6\u30c8\u30d7\u30c3\u30c8\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8<\/h3>\n\n\n\n
\u4eca\u56de\u306fApp\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3001Order\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3068MilkOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3092\u4f7f\u7528\u3057\u307e\u3059\u3002<\/p>\n\n\n\n
\u30fbApp\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8
\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u3068\u30df\u30eb\u30af\u306e\u6570\u91cf\u3092\u30b9\u30c6\u30fc\u30c8\u3067\u4fdd\u6301\u3059\u308b\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3002<\/p>\n\n\n\n
\u30fbOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8
\u5909\u66f4\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u30df\u30eb\u30af\u306e\u6570\u91cf\u3092\u9078\u629e\u3067\u304d\u308b\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3002<\/p>\n\n\n\n
\u30fbMilkOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8
\u30df\u30eb\u30af\u306e\u6570\u91cf\u3092\u9078\u629e\u3067\u304d\u308b\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3002<\/p>\n\n\n\n
App\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8<\/h3>\n\n\n\n
\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u91cf\u3060\u3051\u3067\u306a\u304f\u3001\u30df\u30eb\u30af\u306e\u6570\u91cf\u3082\u30b9\u30c6\u30fc\u30c8\u3067\u7ba1\u7406\u3057\u307e\u3059\u3002\u307e\u305f\u3001MilkOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3078\u30b9\u30c6\u30fc\u30c8\u3092\u6e21\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n
import React from 'react';\nimport Order from '.\/Order';\nimport MilkOrder from '.\/MilkOrder';\n\nfunction App() {\n\n  \/\/ \u9078\u629e\u3055\u308c\u305f\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u3092\u4fdd\u6301\u3059\u308b\u30b9\u30c6\u30fc\u30c8\n  const [orderVal, setOrderVal] = React.useState(1);\n\n  \/\/ \u9078\u629e\u3055\u308c\u305f\u30df\u30eb\u30af\u306e\u6570\u3092\u4fdd\u6301\u3059\u308b\u30b9\u30c6\u30fc\u30c8\n  const [milkOrderVal, setMilkOrderVal] = React.useState(1);\n  \n  \/\/ \u5b50\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3092\u547c\u3073\u51fa\u3059\n  return (\n    <>\n      <Order val={orderVal} setVal={setOrderVal} \/>\n      <MilkOrder val={milkOrderVal} setVal={setMilkOrderVal} \/>\n    <\/>\n  );\n}\n\nexport default App;<\/code><\/pre><\/div>\n\n\n\n
Order\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8<\/h3>\n\n\n\n
\u5909\u66f4\u306f\u306a\u3044\u306e\u3067\u5272\u611b\u3057\u307e\u3059\u3002<\/p>\n\n\n\n
MilkOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8<\/h3>\n\n\n\n
\u30d7\u30e9\u30b9\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068incrementOrder\u95a2\u6570\u304c\u547c\u3070\u308c\u307e\u3059\u3002\u3053\u306e\u95a2\u6570\u306f\u30df\u30eb\u30af\u306e\u6570\u30921\u5897\u3084\u3057\u307e\u3059\u3002\u30df\u30eb\u30af\u306e\u6570\u91cf\u304c3\u4ee5\u4e0a\u306e\u5834\u5408\u3001\u30df\u30eb\u30af\u306e\u6570\u30923\u3078\u8a2d\u5b9a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n
\u30de\u30a4\u30ca\u30b9\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068decrementOrder\u95a2\u6570\u304c\u547c\u3070\u308c\u307e\u3059\u3002\u3053\u306e\u95a2\u6570\u306f\u30df\u30eb\u30af\u306e\u6570\u30921\u6e1b\u3089\u3057\u307e\u3059\u3002\u30df\u30eb\u30af\u306e\u6570\u91cf\u304c1\u4ee5\u4e0b\u306e\u5834\u5408\u3001\u30df\u30eb\u30af\u306e\u6570\u30921\u3078\u8a2d\u5b9a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n
\u30ea\u30bb\u30c3\u30c8\u30dc\u30bf\u30f3\u3092\u62bc\u3059\u3068resetOrder\u95a2\u6570\u304c\u547c\u3070\u308c\u307e\u3059\u3002\u3053\u306e\u95a2\u6570\u306f\u30df\u30eb\u30af\u306e\u6570\u30921\u306b\u3057\u307e\u3059\u3002<\/p>\n\n\n\n
function MilkOrder({val, setVal}) {\n\n    \/\/ \u30df\u30eb\u30af\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u5897\u3084\u3059\n    const incrementOrder = () => {\n\n        \/\/ \u30df\u30eb\u30af\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u304c3\u4ee5\u4e0a\u306e\u5834\u5408\u3001\u30df\u30eb\u30af\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30923\u306b\u3059\u308b\u3002\n        if(val >= 3){\n            setVal(3);\n            return;\n        }\n\n        setVal((val) => val + 1);\n    };\n\n    \/\/ \u30df\u30eb\u30af\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u6e1b\u3089\u3059\n    const decrementOrder = () => {\n\n        \/\/ \u30df\u30eb\u30af\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u304c1\u4ee5\u4e0b\u306e\u5834\u5408\u3001\u30df\u30eb\u30af\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u306b\u3059\u308b\u3002\n        if(val <= 1){\n            setVal(1);\n            return;\n        }\n\n        setVal((val) => val - 1);\n    };\n\n    \/\/ \u30df\u30eb\u30af\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u306b\u3059\u308b\n    const resetOrder = () => setVal(1);\n\n    \/\/ \u30d6\u30e9\u30a6\u30b6\u8868\u793a\u51e6\u7406\n    return (\n      <>\n        <p>\u6ce8\u6587\u3059\u308b\u30df\u30eb\u30af\u306e\u6570\u3092\u6307\u5b9a\u304f\u3060\u3055\u3044\u3002<\/p>\n        <div>\n            <button onClick={incrementOrder}>\u30d7\u30e9\u30b9<\/button>\n            <button onClick={decrementOrder}>\u30de\u30a4\u30ca\u30b9<\/button>\n            <button onClick={resetOrder}>\u30ea\u30bb\u30c3\u30c8<\/button>\n        <\/div>\n        <p>\u30df\u30eb\u30af\u306e\u6570\uff1a{val}<\/p>\n      <\/>\n    );\n  }\n  \n  export default MilkOrder;<\/code><\/pre><\/div>\n\n\n\n
\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af<\/h2>\n\n\n\n
\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u306e\u8a2d\u5b9a\u3082\u30df\u30eb\u30af\u306e\u6570\u306e\u8a2d\u5b9a\u3082\u540c\u3058\u4e8b\u3092\u3084\u3063\u3066\u3044\u308b\u4e8b\u306b\u6c17\u3065\u3044\u305f\u4e8b\u3067\u3057\u3087\u3046\u3002\u3053\u308c\u3092\u5171\u901a\u5316\u3057\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u3068\u3057\u3066\u4f7f\u7528\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n
\u5171\u901a\u5316<\/h3>\n\n\n\n
hooks.js \u3068\u3044\u3046\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u6210\u3057\u307e\u3059\u3002\u540d\u524d\u306f\u306a\u3093\u3067\u3082\u3044\u3044\u3067\u3059\u3002\u3053\u306e\u30d5\u30a1\u30a4\u30eb\u306b\u30d5\u30c3\u30af\u3092\u96c6\u7d04\u3059\u308b\u3068\u3044\u3046\u610f\u5473\u3067 hooks \u3068\u3044\u3046\u540d\u79f0\u306b\u3057\u307e\u3057\u305f\u3002<\/p>\n\n\n\n
useOrderCount\u3068\u3044\u3046\u95a2\u6570\u3092\u4f5c\u6210\u3057\u307e\u3057\u305f\u3002\u6ce8\u6587\u306e\u6570\u91cf\u3092\u30b9\u30c6\u30fc\u30c8\u3067\u4fdd\u6301\u3057\u3066\u3044\u307e\u3059\u3002
\u5148\u7a0b\u306f\u3001\u30b3\u30fc\u30d2\u30fc\u3082\u30df\u30eb\u30af\u3082\u6ce8\u6587\u6570\u304c\u540c\u3058\u3088\u3046\u306b\u9078\u3079\u307e\u3057\u305f\u3002\u3053\u308c\u3092\u5171\u901a\u5316\u3059\u308b\u70ba\u3001\u6ce8\u6587\u30921\u5897\u3084\u3059\u95a2\u6570(incrementOrder)\u3001\u6ce8\u6587\u30921\u6e1b\u3089\u3059\u95a2\u6570(decrementOrder)\u3001\u6ce8\u6587\u3092\u30ea\u30bb\u30c3\u30c8\u3059\u308b\u95a2\u6570(resetOrder)\u3092\u4f5c\u6210\u3057\u307e\u3057\u305f\u3002
\u8fd4\u5374\u5024\u306f\u914d\u5217\u3067\u3001\u7b2c\u4e00\u5f15\u6570\u306f\u6ce8\u6587\u6570\u3001\u7b2c\u4e8c\u5f15\u6570\u306f\u3001\u6ce8\u6587\u30921\u5897\u3084\u3059\u95a2\u6570\u3001\u6ce8\u6587\u30921\u6e1b\u3089\u3059\u95a2\u6570\u3001\u6ce8\u6587\u3092\u30ea\u30bb\u30c3\u30c8\u3059\u308b\u95a2\u6570\u3092\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3067\u8fd4\u5374\u3057\u3066\u3044\u307e\u3059\u3002
\u306a\u304a\u3001\u95a2\u6570\u540d\u306f\u30d5\u30c3\u30af\u3092\u4f7f\u3046\u3068\u3044\u3046\u3053\u3068\u304b\u3089\u30d7\u30ec\u30d5\u30a3\u30c3\u30af\u30b9\u306b “use” \u3092\u3064\u3051\u3066 “use\u301c” \u3068\u3044\u3046\u540d\u79f0\u306b\u3059\u308b\u306e\u304c\u4e00\u822c\u7684\u306e\u3088\u3046\u3067\u3059\u3002<\/p>\n\n\n\n
import React from 'react';\n\nexport const useOrderCount = (val=1) => {\n\n    \/\/ \u6ce8\u6587\u306e\u6570\u91cf\u3092\u7ba1\u7406\u3059\u308b\u30b9\u30c6\u30fc\u30c8\n    const [orderVal, setOrderVal] = React.useState(val);\n\n    \/\/ \u6ce8\u6587\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u5897\u3084\u3059\n    const incrementOrder = () => {\n\n        \/\/ \u6ce8\u6587\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u304c3\u4ee5\u4e0a\u306e\u5834\u5408\u3001\u6ce8\u6587\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30923\u306b\u3059\u308b\u3002\n        if(orderVal >= 3){\n            setOrderVal(3);\n            return;\n        }\n\n        setOrderVal((orderVal) => orderVal + 1);\n    };\n\n    \/\/ \u6ce8\u6587\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u6e1b\u3089\u3059\n    const decrementOrder = () => {\n\n        \/\/ \u6ce8\u6587\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u304c1\u4ee5\u4e0b\u306e\u5834\u5408\u3001\u6ce8\u6587\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u306b\u3059\u308b\u3002\n        if(orderVal <= 1){\n            setOrderVal(1);\n            return;\n        }\n\n        setOrderVal((orderVal) => orderVal - 1);\n    };\n\n    \/\/ \u6ce8\u6587\u306e\u30aa\u30fc\u30c0\u30fc\u6570\u30921\u306b\u3059\u308b\n    const resetOrder = () => setOrderVal(1);\n\n    \/\/ \u7b2c\u4e00\u5f15\u6570\u306b\u306f\u30c7\u30fc\u30bf\u3001\u7b2c\u4e8c\u5f15\u6570\u306b\u306f\u30c7\u30fc\u30bf\u3092\u66f4\u65b0\u3059\u308b\u95a2\u6570\u3068\u3057\u3066\u914d\u5217\u3092\u8fd4\u5374\u3059\u308b\u3002\n    return [orderVal, {incrementOrder, decrementOrder, resetOrder}];\n};<\/code><\/pre><\/div>\n\n\n\n
\u3053\u306e\u3088\u3046\u306b\u30d5\u30c3\u30af(\u4eca\u56de\u306f\u30b9\u30c6\u30fc\u30c8)\u3092\u5229\u7528\u3057\u305f\u95a2\u6570\u3092\u518d\u5229\u7528\u3059\u308b\u4e8b\u3092\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u3068\u8a00\u3044\u307e\u3059\u3002<\/p>\n\n\n\n
\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u306e\u5229\u7528<\/h3>\n\n\n\n
\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u306e\u5229\u7528\u306f\u7c21\u5358\u3067\u3001\u5148\u7a0b\u306e hooks \u304b\u3089\u30a8\u30af\u30b9\u30dd\u30fc\u30c8\u3055\u308c\u305f\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af(useOrderCount) \u3092\u30a4\u30f3\u30dd\u30fc\u30c8\u3057\u3066\u4f7f\u7528\u3059\u308b\u3060\u3051\u3067\u3059\u3002<\/p>\n\n\n\n
\u4ee5\u4e0b\u306fApp\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u306b\u306a\u308a\u307e\u3059\u3002\u30ab\u30b9\u30bf\u30e0\u30d5\u30c3\u30af\u304b\u3089\u8fd4\u5374\u3055\u308c\u308b\u5024\u3092\u3001\u5404\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3078\u6e21\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n
import React from 'react';\nimport { useOrderCount } from ".\/hooks";\nimport Order from '.\/Order';\nimport MilkOrder from '.\/MilkOrder';\n\nfunction App() {\n\n  \/\/ \u9078\u629e\u3055\u308c\u305f\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u3092\u4fdd\u6301\u3059\u308b\u30b9\u30c6\u30fc\u30c8\n  const [cofferOrderVal, funcA] = useOrderCount(1);\n\n  \/\/ \u9078\u629e\u3055\u308c\u305f\u30df\u30eb\u30af\u306e\u6570\u3092\u4fdd\u6301\u3059\u308b\u30b9\u30c6\u30fc\u30c8\n  const [milkOrderVal, funcB] = useOrderCount(1);\n  \n  \/\/ \u5b50\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3092\u547c\u3073\u51fa\u3059\n  return (\n    <>\n      <Order val={cofferOrderVal} setVal={funcA} \/>\n      <MilkOrder val={milkOrderVal} setVal={funcB} \/>\n    <\/>\n  );\n}\n\nexport default App;<\/code><\/pre><\/div>\n\n\n\n
\u6ce8\u6587\u6570\u306e\u8868\u793a<\/h3>\n\n\n\n
\u6700\u5f8c\u306b\u30b3\u30fc\u30d2\u30fc\u306e\u6ce8\u6587\u6570\u3092\u8868\u793a\u3059\u308bOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3068\u3001\u30df\u30eb\u30af\u306e\u6ce8\u6587\u6570\u3092\u8868\u793a\u3059\u308bMilkOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n
\u4ee5\u4e0b\u306f\u3001Order\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3067\u3059\u3002<\/p>\n\n\n\n
function Order({val, setVal}) {\n\n    \/\/ \u30d6\u30e9\u30a6\u30b6\u8868\u793a\u51e6\u7406\n    return (\n      <>\n        <p>\u6ce8\u6587\u3059\u308b\u30b3\u30fc\u30d2\u30fc\u306e\u6570\u3092\u6307\u5b9a\u304f\u3060\u3055\u3044\u3002<\/p>\n        <div>\n            <button onClick={setVal.incrementOrder}>\u30d7\u30e9\u30b9<\/button>\n            <button onClick={setVal.decrementOrder}>\u30de\u30a4\u30ca\u30b9<\/button>\n            <button onClick={setVal.resetOrder}>\u30ea\u30bb\u30c3\u30c8<\/button>\n        <\/div>\n        <p>\u30b3\u30fc\u30d2\u30fc\u306e\u6570\uff1a{val}<\/p>\n      <\/>\n    );\n  }\n  \n  export default Order;<\/code><\/pre><\/div>\n\n\n\n
\u4ee5\u4e0b\u306f\u3001MilkOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3067\u3059\u3002<\/p>\n\n\n\n
function MilkOrder({val, setVal}) {\n\n    \/\/ \u30d6\u30e9\u30a6\u30b6\u8868\u793a\u51e6\u7406\n    return (\n      <>\n        <p>\u6ce8\u6587\u3059\u308b\u30df\u30eb\u30af\u306e\u6570\u3092\u6307\u5b9a\u304f\u3060\u3055\u3044\u3002<\/p>\n        <div>\n            <button onClick={setVal.incrementOrder}>\u30d7\u30e9\u30b9<\/button>\n            <button onClick={setVal.decrementOrder}>\u30de\u30a4\u30ca\u30b9<\/button>\n            <button onClick={setVal.resetOrder}>\u30ea\u30bb\u30c3\u30c8<\/button>\n        <\/div>\n        <p>\u30df\u30eb\u30af\u306e\u6570\uff1a{val}<\/p>\n      <\/>\n    );\n  }\n  \n  export default MilkOrder;<\/code><\/pre><\/div>\n\n\n\n
Order\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3001MilkOrder\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8 \u3068\u3082\u306b\u6570\u91cf\u3092\u5909\u66f4\u3059\u308b\u95a2\u6570\u304c\u5f15\u6570\u3067\u6e21\u3055\u308c\u308b\u70ba\u3001\u8a18\u8f09\u304c\u306a\u304f\u306a\u308a\u30b9\u30c3\u30ad\u30ea\u3057\u307e\u3057\u305f\u3002<\/p>\n\n\n\n
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