{"id":1359,"date":"2021-10-01T17:57:30","date_gmt":"2021-10-01T08:57:30","guid":{"rendered":"https:\/\/weseek.co.jp\/tech\/?p=1359"},"modified":"2023-04-17T10:28:18","modified_gmt":"2023-04-17T01:28:18","slug":"%e3%80%90node-js%e3%80%91-eventemitter%e3%81%ae%e4%bd%bf%e3%81%84%e6%96%b9%e8%a7%a3%e8%aa%ac","status":"publish","type":"post","link":"https:\/\/weseek.co.jp\/tech\/1359\/","title":{"rendered":"Node.js|EventEmitter\u306e\u4f7f\u3044\u65b9\u89e3\u8aac"},"content":{"rendered":"<p>\u3053\u306e\u6295\u7a3f\u306f\u3001\u5f0a\u793e\u304c\u63d0\u4f9b\u3059\u308bWESEEK TECH\u901a\u4fe1\u306e\u4e00\u74b0\u3067\u3059\u3002<br \/>\nWESEEK TECH\u901a\u4fe1\u3068\u306f\u3001WESEEK\u306e\u30a8\u30f3\u30b8\u30cb\u30a2\u304c\u30ad\u30e3\u30c3\u30c1\u30a2\u30c3\u30d7\u3057\u305f\u6280\u8853\u306b\u95a2\u3059\u308b\u60c5\u5831\u3092\u3001tech\u30d6\u30ed\u30b0\u3092\u901a\u3058\u3066\u5b9a\u671f\u7684\u306b\u767a\u4fe1\u3057\u3066\u3044\u304f\u3082\u306e\u3067\u3059\u3002<\/p>\n<h2>\u306f\u3058\u3081\u306b<\/h2>\n<p>\u3053\u3093\u306b\u3061\u306f\u3001\u30b7\u30b9\u30c6\u30e0\u30a8\u30f3\u30b8\u30cb\u30a2\u306e <a href=\"https:\/\/github.com\/kaoritokashiki\">\u304b\u304a\u308a<\/a> \u3067\u3059\u3002\u672c\u8a18\u4e8b\u3067\u306f\u3001Node.js\u306eEventEmitter\u306b\u3064\u3044\u3066\u304a\u8a71\u3057\u307e\u3059\u3002\u3053\u306e\u8a18\u4e8b\u3067\u53d6\u308a\u4e0a\u3052\u308b\u5185\u5bb9\u306f\u4ee5\u4e0b\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n<p><!--more--><\/p>\n<h2>Event Emitter \u3068\u306f<\/h2>\n<p>\u4f55\u304b\u306e\u30a4\u30d9\u30f3\u30c8\u304c\u767a\u751f\u3057\u305f\u6642\u306b\u3001\u305d\u308c\u304c\u30c8\u30ea\u30ac\u30fc\u3068\u306a\u3063\u3066\u3001\u3042\u3089\u304b\u3058\u3081\u767b\u9332\u3057\u3066\u304a\u3044\u305f\u51e6\u7406\u3092\u5b9f\u884c\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<h2>Event Emitter \u306e\u4f5c\u6210<\/h2>\n<p>Event Emitter\u3092\u4f5c\u6210\u3059\u308b\u306b\u306f\u3001Node.js\u306e<code>events<\/code>\u30e2\u30b8\u30e5\u30fc\u30eb\u304b\u3089EventEmitter\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u751f\u6210\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-javascript\">const EventEmitter = require(&#039;events&#039;);\nconst myEmitter = new EventEmitter(); \/\/ EventEmitter\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u751f\u6210<\/code><\/pre>\n<h2>\u30a4\u30d9\u30f3\u30c8\u306e\u767a\u52d5\u3068\u3001\u305d\u308c\u306b\u5bfe\u5fdc\u3059\u308b\u51e6\u7406<\/h2>\n<p>Event Emitter\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u3057\u3066\u3001<code>on()<\/code>\u3068<code>emit()<\/code>\u95a2\u6570\u306b\u3064\u3044\u3066\u304a\u8a71\u3057\u307e\u3059\u3002<\/p>\n<ul>\n<li>\n<p><code>on(eventName , listener )<\/code><br \/>\n\u7b2c\u4e00\u5f15\u6570\u306b\u6307\u5b9a\u3057\u305f\u30a4\u30d9\u30f3\u30c8\u306b\u7d10\u3065\u3051\u3066\u3001listener\u3092\u767b\u9332\u3057\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><code>emit(eventName , [args])<\/code><br \/>\n\u3053\u306e\u95a2\u6570\u3067\u30a4\u30d9\u30f3\u30c8\u304c\u767a\u52d5\u3057\u3001\u7b2c\u4e8c\u5f15\u6570\u4ee5\u964d\u306eargs\u3092\u5f15\u6570\u3068\u3057\u3066\u6e21\u3057\u307e\u3059\u3002<\/p>\n<\/li>\n<\/ul>\n<p><code>emit()<\/code>\u95a2\u6570\u3067\u30a4\u30d9\u30f3\u30c8\u304c\u767a\u52d5\u3057\u3001<code>on()<\/code>\u95a2\u6570\u3067\u767b\u9332\u3055\u308c\u3066\u3044\u305f\u51e6\u7406\u304c\u5b9f\u884c\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-javascript\">import { EventEmitter } from &#039;events&#039;;\nconst eventEmitter = new EventEmitter();\n\n\/\/ \u30a4\u30d9\u30f3\u30c8\u304c\u767a\u52d5\u3055\u308c\u305f\u6642\u306e\u51e6\u7406\u3092\u8a18\u8ff0\u3059\u308b\neventEmitter.on(&#039;myEvent&#039;, () =&gt; {\n    console.log(&#039;Emitted Event&#039;);\n});\n\n\/\/ \u30a4\u30d9\u30f3\u30c8\u3092\u767a\u52d5\u3055\u305b\u308b\neventEmitter.emit(&#039;myEvent&#039;);<\/code><\/pre>\n<p>\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u304c\u5b9f\u884c\u3055\u308c\u305f\u6642\u306b\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u51fa\u529b\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-javascript\">> Emitted Event<\/code><\/pre>\n<p>\u203b<code>on()<\/code>\u3092\u4f7f\u3063\u3066\u767b\u9332\u3055\u308c\u305flistener\u306f\u3001\u305d\u306e\u30a4\u30d9\u30f3\u30c8\u304c\u767a\u706b\u3055\u308c\u308b\u5ea6\u306b\u5b9f\u884c\u3055\u308c\u307e\u3059\u3002<\/p>\n<h2>\u540c\u671f\u304b\u975e\u540c\u671f\u304b<\/h2>\n<p>Event Emitter\u306b\u3088\u3063\u3066\u767a\u751f\u3057\u305f\u30a4\u30d9\u30f3\u30c8\u306f\u3001\u540c\u671f\u7684\u306b\u5b9f\u884c\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-javascript\">import { EventEmitter } from &#039;events&#039;;\nconst eventEmitter = new EventEmitter();\n\neventEmitter.on(&#039;myEvent&#039;, (data) =&gt; {\n    console.log(data);\n});\n\nconsole.log(&#039;A&#039;);\neventEmitter.emit(&#039;myEvent&#039;, &#039;B&#039;);\nconsole.log(&quot;C&quot;); <\/code><\/pre>\n<p>\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u3092\u5b9f\u884c\u3057\u305f\u5834\u5408\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u4e0a\u304b\u3089\u9806\u756a\u306b\u51fa\u529b\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-javascript\">> A\n> B\n> C<\/code><\/pre>\n<h2>listener\u306e\u5b9f\u884c\u9806\u5e8f<\/h2>\n<p>EventEmitter\u306b\u3088\u3063\u3066\u767a\u751f\u3057\u305f\u30a4\u30d9\u30f3\u30c8\u306f\u3001\u767b\u9332\u3055\u308c\u305f\u5168\u3066\u306elistener\u304c\u9806\u756a\u306b\u5b9f\u884c\u3055\u308c\u307e\u3059<\/p>\n<pre><code class=\"language-javascript\">import { EventEmitter } from &#039;events&#039;;\nconst eventEmitter = new EventEmitter();\n\neventEmitter.on(&#039;myEvent&#039;, (data) =&gt; {\n    console.log(data, &#039;FIRST&#039;);\n});\n\nconsole.log(&#039;A&#039;);\n\neventEmitter.on(&quot;myEvent&quot;, data =&gt; {\n    console.log(data, &#039;SECOND&#039;);\n});\n\n\/\/ \u30a4\u30d9\u30f3\u30c8\u306e\u767a\u52d5\neventEmitter.emit(&#039;myEvent&#039;, &#039;Emitted Statement:&#039;);\n\nconsole.log(&quot;B&quot;);<\/code><\/pre>\n<p>\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u304c\u5b9f\u884c\u3055\u308c\u305f\u5834\u5408\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u51fa\u529b\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-javascript\">> A\n> Emitted Statement: FIRST\n> Emitted Statement: SECOND\n> B<\/code><\/pre>\n<h2>\u3042\u308b\u7279\u5b9a\u306e\u30a4\u30d9\u30f3\u30c8\u306b\u5bfe\u3057\u3066\u53cd\u5fdc\u3055\u305b\u308b\u306b\u306f\u3001\u540c\u3058EventEmitter\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304b\u3089emit\u3092\u5b9f\u884c\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b<\/h2>\n<p><code>on()<\/code>\u3067\u767b\u9332\u3057\u305f\u30a4\u30d9\u30f3\u30c8\u30cf\u30f3\u30c9\u30e9\u3092\u30c8\u30ea\u30ac\u30fc\u3059\u308b\u306b\u306f\u3001\u540c\u3058<code>EventEmitter<\/code>\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306e<code>emit()<\/code>\u3092\u547c\u3073\u51fa\u3059\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u3067\u306f\u3001\u5225\u306eEventEmitter\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u4f7f\u7528\u3055\u308c\u3066\u3044\u308b\u305f\u3081\u3001\u30b3\u30f3\u30bd\u30fc\u30eb\u306b\u306f\u4f55\u3082\u51fa\u529b\u3055\u308c\u307e\u305b\u3093\u3002<\/p>\n<pre><code class=\"language-javascript\">import { EventEmitter } from &#039;events&#039;;\n\nconst eventEmitter1 = new EventEmitter();\neventEmitter1.on(&#039;myEvent&#039;, () =&gt; {\n    console.log(&#039;myEvent emitted&#039;);\n});\n\nconst eventEmitter2 = new EventEmitter();\neventEmitter2.emit(&#039;myEvent&#039;);<\/code><\/pre>\n<p>\u5b9f\u969b\u306e\u5229\u7528\u6642\u306b\u306f\u8907\u6570\u306eEventEmitter\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u4f7f\u3046\u3053\u3068\u306f\u7a00\u3060\u3068\u601d\u3044\u307e\u3059\u304c\u3001\u30a4\u30d9\u30f3\u30c8\u304c\u4f1d\u64ad\u3057\u306a\u3044\u7b49\u306e\u75c7\u72b6\u304c\u8d77\u3053\u3063\u305f\u5834\u5408\u306f\u3053\u306e\u8fba\u308a\u3082\u7591\u3063\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<h2>Event Emitter \u30af\u30e9\u30b9\u306e\u95a2\u6570<\/h2>\n<p>EventEmitter\u30af\u30e9\u30b9\u306e\u4e2d\u3067\u3001<code>on()<\/code> <code>emit()<\/code>\u4ee5\u5916\u306e\u95a2\u6570\u3092\u53d6\u308a\u4e0a\u3052\u307e\u3059\u3002<\/p>\n<ul>\n<li>\n<p><code>once(eventName, listener)<\/code><br \/>\nlistener\u3092\u4e00\u5ea6\u3060\u3051\u5b9f\u884c\u3057\u305f\u3044\u5834\u5408\u306b\u4f7f\u7528\u3055\u308c\u307e\u3059\u3002<br \/>\n\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u30a4\u30d9\u30f3\u30c8\u3092\u30ea\u30c3\u30b9\u30f3\u3057\u305f\u5f8c\u306b\u3001listener\u304c\u7834\u68c4\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><code>addListener(eventName, listener)<\/code><br \/>\n\u3053\u308c\u306f<code>on()<\/code>\u306e\u30a8\u30a4\u30ea\u30a2\u30b9\u3067\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><code>removeListener(eventName, listener)<\/code><br \/>\n\u3053\u308c\u306f\u3001listener\u3092\u524a\u9664\u3059\u308b\u305f\u3081\u306b\u4f7f\u7528\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><code>removeAllListeners([eventName])<\/code><br \/>\n\u3053\u308c\u306f\u3001 eventName \u306b\u767b\u9332\u3055\u308c\u3066\u3044\u308b\u5168\u3066\u306e listener \u3092\u53d6\u308a\u9664\u304d\u307e\u3059\u3002<\/p>\n<\/li>\n<\/ul>\n<h2>Event Emitter \u306e\u4f7f\u3044\u6240<\/h2>\n<p>\u5f0a\u793e\u3067\u958b\u767a\u4e2d\u306e\u30ca\u30ec\u30c3\u30b8\u5171\u6709\u30b5\u30fc\u30d3\u30b9\u300c<a href=\"https:\/\/growi.org\/ja\/\">GROWI<\/a>\u300d\u3092\u4f8b\u306b\u51fa\u3057\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<br \/>\nGROWI\u3067\u306f\u3001\u30da\u30fc\u30b8\u306b\u30b3\u30e1\u30f3\u30c8\u304c\u8ffd\u52a0\u3055\u308c\u305f\u6642\u306bDB\u306b\u30b3\u30e1\u30f3\u30c8\u306e\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u304c\u4fdd\u5b58\u3055\u308c\u307e\u3059\u3002<\/p>\n<p>DB\u306b\u30c7\u30fc\u30bf\u304c\u4fdd\u5b58\u3055\u308c\u305f\u30bf\u30a4\u30df\u30f3\u30b0\u3067\u7279\u5b9a\u306e\u51e6\u7406\u3092\u3057\u305f\u3044\u6642\u306b\u306f\u3001Model\u30b9\u30ad\u30fc\u30de\u304c\u63d0\u4f9b\u3059\u308bpost save hook\u3092\u5229\u7528\u3057\u3066\u5b9f\u884c\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<p>\u305f\u3060\u3057\u3001\u6ce8\u610f\u70b9\u3068\u3057\u3066\u3001\u30e2\u30c7\u30eb\u304b\u3089\u30b5\u30fc\u30d3\u30b9\u5c64\u306a\u3069\u3067\u5b9a\u7fa9\u3055\u308c\u305f\u95a2\u6570\u3092\u76f4\u63a5\u547c\u3073\u51fa\u3059\u306e\u306f\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u306e\u8a2d\u8a08\u7684\u306b\u3088\u304f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n<p>\u305d\u3053\u3067\u3001post save hook\u306b\u3066EventEmitter\u3067\u30a4\u30d9\u30f3\u30c8\u3092\u767a\u706b\u3001\u305d\u308c\u3092\u30b5\u30fc\u30d3\u30b9\u5c64\u3067\u691c\u77e5\u3057\u3066\u767b\u9332\u3057\u3066\u3044\u305f\u51e6\u7406\u3092\u5b9f\u884c\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<h2>React \u2716\ufe0f  EventEmitter<\/h2>\n<p>React\u3067\u72b6\u614b\u7ba1\u7406\u306bEventEmitter\u3092\u4f7f\u7528\u3059\u308b<br \/>\n\u4ee5\u4e0b\u306e\u8a18\u4e8b\u304c\u53c2\u8003\u306b\u306a\u308a\u307e\u3059\u306e\u3067\u3001\u3088\u3051\u308c\u3070\u30c1\u30a7\u30c3\u30af\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<ul>\n<li><a href=\"https:\/\/medium.com\/@krzakmarek88\/eventemitter-instead-of-lifting-state-up-f5f105054a5\">Event Emitter instead of lifting state up in React<\/a><\/li>\n<\/ul>\n<h2>\u307e\u3068\u3081<\/h2>\n<p>EventEmitter\u306f<\/p>\n<ul>\n<li>\u4f55\u304b\u3057\u3089\u306e\u30a4\u30d9\u30f3\u30c8\u3092\u30c8\u30ea\u30ac\u30fc\u3068\u3057\u3066\u3001\u51e6\u7406\u3092\u5b9f\u884c\u3059\u308b<\/li>\n<li>\u30a4\u30d9\u30f3\u30c8\u306b\u767b\u9332\u3055\u308c\u3066\u3044\u308blistener\u3092\u540c\u671f\u7684\u306b\u547c\u3073\u51fa\u3059<\/li>\n<li>\u30a4\u30d9\u30f3\u30c8\u306b\u767b\u9332\u3055\u308c\u3066\u3044\u308blistener\u3092\u767b\u9332\u3055\u308c\u305f\u9806\u756a\u306b\u547c\u3073\u51fa\u3059<\/li>\n<\/ul>\n<p>\u3044\u304b\u304c\u3067\u3057\u305f\u3067\u3057\u3087\u3046\u304b\u3002<br \/>\n\u6700\u5f8c\u307e\u3067\u8aad\u3093\u3067\u304f\u3060\u3055\u308a\u3042\u308a\u304c\u3068\u3046\u3054\u3056\u3044\u307e\u3057\u305f\uff01<\/p>\n<h2>\u53c2\u8003\u306b\u3055\u305b\u3066\u3044\u305f\u3060\u3044\u305f\u8a18\u4e8b<\/h2>\n<ul>\n<li><a href=\"https:\/\/nodejs.org\/api\/events.html\">Events | Node.js v16.10.0 documentation<\/a><\/li>\n<li><a href=\"https:\/\/medium.com\/developers-arena\/nodejs-event-emitters-for-beginners-and-for-experts-591e3368fdd2\">Node Event Emitters \u2014 For Beginners and Experts<\/a><\/li>\n<li><a href=\"https:\/\/www.whizz-tech.co.jp\/1659\/#EventEmitterremoveListener\">Node.js\u306eEventEmitter\u3067\u30a4\u30d9\u30f3\u30c8\u99c6\u52d5\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3092\u3059\u308b<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\u3053\u306e\u6295\u7a3f\u306f\u3001\u5f0a\u793e\u304c\u63d0\u4f9b\u3059\u308bWESEEK TECH\u901a\u4fe1\u306e\u4e00\u74b0\u3067\u3059\u3002 WESEEK TECH\u901a\u4fe1\u3068\u306f\u3001WESEEK\u306e\u30a8\u30f3\u30b8\u30cb\u30a2\u304c\u30ad\u30e3\u30c3\u30c1\u30a2\u30c3\u30d7\u3057\u305f\u6280\u8853\u306b\u95a2\u3059\u308b\u60c5\u5831\u3092\u3001tech\u30d6\u30ed\u30b0\u3092\u901a\u3058\u3066\u5b9a\u671f\u7684\u306b\u767a\u4fe1\u3057\u3066\u3044\u304f\u3082\u306e\u3067\u3059\u3002 \u306f\u3058<\/p>\n","protected":false},"author":3,"featured_media":2119,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[31,52],"tags":[],"_links":{"self":[{"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/posts\/1359"}],"collection":[{"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/comments?post=1359"}],"version-history":[{"count":30,"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/posts\/1359\/revisions"}],"predecessor-version":[{"id":4035,"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/posts\/1359\/revisions\/4035"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/media\/2119"}],"wp:attachment":[{"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/media?parent=1359"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/categories?post=1359"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/weseek.co.jp\/tech\/wp-json\/wp\/v2\/tags?post=1359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}