{"id":10542,"date":"2020-05-09T02:47:00","date_gmt":"2020-05-08T17:47:00","guid":{"rendered":"http:\/\/www.code-magagine.com\/?p=10542"},"modified":"2023-05-27T20:56:15","modified_gmt":"2023-05-27T11:56:15","slug":"%e3%80%90javascript%e3%80%91%e9%85%8d%e5%88%97%e3%81%ae%e4%be%bf%e5%88%a9%e3%83%a1%e3%82%bd%e3%83%83%e3%83%89%e3%80%8cmap%e3%80%8d%e3%81%ab%e3%81%a4%e3%81%84%e3%81%a6","status":"publish","type":"post","link":"http:\/\/www.code-magagine.com\/?p=10542","title":{"rendered":"\u3010JavaScript\u3011\u914d\u5217\u306e\u4fbf\u5229\u30e1\u30bd\u30c3\u30c9\u300cmap\u300d\u3001\u300cfilter\u300d\u3001\u300cfind\u300d\u3001\u300creduce\u300d\u306b\u3064\u3044\u3066"},"content":{"rendered":"<h2>map\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f<\/h2>\n<p><span style=\"color: #ff0000;\"><strong>\u65e2\u5b58\u306e\u914d\u5217\u3092\u52a0\u5de5\u3057\u3066\u65b0\u3057\u3044\u914d\u5217\u3092\u4f5c\u6210\u3059\u308b\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9<\/strong><\/span>\u3067\u3059\u3002<\/p>\n<h3>\u69cb\u6587<\/h3>\n<pre class=\"lang:default decode:true\">let \u65b0\u3057\u3044\u914d\u5217 = \u914d\u5217.map(function(\u914d\u5217\u306e\u8981\u7d20){\r\n  return \u914d\u5217\u306e\u8981\u7d20\u306e\u5024;\r\n});<\/pre>\n<h3>\u30dd\u30a4\u30f3\u30c8<\/h3>\n<ul>\n<li>\u65e2\u5b58\u306e\u914d\u5217\u306e\u5185\u5bb9\u3092\u5909\u3048\u305a\u306b\u65b0\u3057\u3044\u914d\u5217\u306b\u683c\u7d0d\u3057\u3066\u304f\u308c\u307e\u3059\u3002<\/li>\n<\/ul>\n<h3>forEach\u3068\u306e\u9055\u3044<\/h3>\n<p><span style=\"color: #ff0000;\"><strong>\u30b3\u30fc\u30eb\u30d0\u30c3\u30af\u95a2\u6570\u306e\u4e2d\u3067\u5fc5\u305areturn\u3092\u3057\u307e\u3059\u3002<\/strong><\/span>return\u3092\u3057\u305f\u5024\u304c\u65b0\u3057\u3044\u914d\u5217\u306e\u65b0\u3057\u3044\u8981\u7d20\u306e\u4e00\u3064\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<h3>\u7528\u9014<\/h3>\n<ul>\n<li>\u5927\u91cf\u306b\u9805\u76ee\u304c\u3042\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4e2d\u304b\u3089\u8868\u793a\u306b\u5fc5\u8981\u306a\u7279\u5b9a\u306e\u9805\u76ee\u306e\u307f\u62bd\u51fa\u3057\u3066\u4f7f\u3044\u305f\u3044\u3068\u8a00\u3063\u305f\u5834\u5408\u306b\u4f7f\u3044\u307e\u3059\u3002<\/li>\n<\/ul>\n<h3>\u4f8b<\/h3>\n<h4>\u8a08\u7b97\u7d50\u679c\u3092\u5143\u306b\u65b0\u3057\u3044\u914d\u5217\u3092\u4f5c\u308b<\/h4>\n<pre class=\"lang:default decode:true\">let nums = [1,2,3];\r\nlet squared = nums.map(function(num){\r\n  return num * num;\r\n});\r\nsquared; \/\/[1,4,9]<\/pre>\n<h4>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304b\u3089\u7279\u5b9a\u306e\u8981\u7d20\u3092\u629c\u304d\u51fa\u3057\u914d\u5217\u3092\u4f5c\u308b\u3002<\/h4>\n<pre class=\"lang:default decode:true\">let cats = [\r\n  { name:'\u592a\u90ce',kind:'\u4e09\u6bdb\u732b' },\r\n  { name:'\u82b1\u5b50',kind:'\u30da\u30eb\u30b7\u30e3\u732b' }\r\n]\r\nlet kinds = cats.map(function(cat){\r\n  return cat.kind;\r\n});\r\nkinds; \/\/['\u4e09\u6bdb\u732b','\u30da\u30eb\u30b7\u30e3\u732b']<\/pre>\n<h2>filter\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f<\/h2>\n<h3>\u7528\u9014<\/h3>\n<p>\u4e00\u89a7\u8868\u793a\u3055\u308c\u3066\u3044\u308b\u30c7\u30fc\u30bf\u306e\u4e2d\u304b\u3089\u7279\u5b9a\u306e\u30c7\u30fc\u30bf\u3092\u62bd\u51fa\u3057\u305f\u3044\u5834\u5408\u7b49\u306b\u4f7f\u3044\u307e\u3059\u3002<\/p>\n<h3>\u69cb\u6587<\/h3>\n<pre class=\"lang:default decode:true\">\u914d\u5217.filter(function(\u914d\u5217\u306e\u8981\u7d20){\r\n  return true(\u65b0\u3057\u3044\u914d\u5217\u306e\u8981\u7d20)\/false(\u914d\u5217\u306e\u8981\u7d20\u304b\u3089\u306f\u9664\u5916)\r\n});<\/pre>\n<h3>\u4f8b<\/h3>\n<h4>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u914d\u5217\u304b\u3089\u6761\u4ef6\u306b\u5408\u3046\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u307f\u62bd\u51fa\u3059\u308b\u3002<\/h4>\n<pre class=\"lang:default decode:true \">let cats = [\r\n  { name:'\u592a\u90ce',kind:'\u4e09\u6bdb\u732b' },\r\n  { name:'\u82b1\u5b50',kind:'\u30da\u30eb\u30b7\u30e3\u732b' },\r\n  { name:'\u6b21\u90ce',kind:'\u4e09\u6bdb\u732b' }\r\n]\r\nlet kinds = cats.filter(function(cat){\r\n  return cat.kind === '\u4e09\u6bdb\u732b';\r\n});\r\nkinds;\u3000\/\/[{\"name\":\"\u592a\u90ce\",\"kind\":\"\u4e09\u6bdb\u732b\"},{\"name\":\"\u6b21\u90ce\",\"kind\":\"\u4e09\u6bdb\u732b\"}]<\/pre>\n<h2>find\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f<\/h2>\n<p>\u914d\u5217\u304b\u3089\u6700\u521d\u306b\u898b\u3064\u304b\u3063\u305f\u8981\u7d20\u3092\u5024\u3068\u3057\u3066\u8fd4\u3057\u307e\u3059\u3002<\/p>\n<h3>\u7528\u9014<\/h3>\n<ul>\n<li>\u30b5\u30fc\u30d0\u30fc\u304b\u3089API\u3067\u53d6\u5f97\u3057\u305f\u4e00\u89a7\u30c7\u30fc\u30bf\u304b\u3089\u4e00\u610f\u306e\u7279\u5b9a\u306e\u30c7\u30fc\u30bf\u3092\u62bd\u51fa\u3059\u308b\u305f\u3081\u306b\u4f7f\u7528\u3057\u307e\u3059\u3002<\/li>\n<\/ul>\n<h3>\u4f8b<\/h3>\n<pre class=\"lang:default decode:true \">let animals = ['\u72ac','\u732b','\u30e9\u30a4\u30aa\u30f3']\r\nlet pet = animals.find(function(animal){\r\n  return animal === '\u72ac';\r\n});\r\npet; \/\/\u72ac<\/pre>\n<h2>reduce\u30e1\u30bd\u30c3\u30c9<\/h2>\n<h3>\u69cb\u6587<\/h3>\n<pre class=\"lang:default decode:true \">let numbers = [1,2,3,5];\r\n\r\n\u914d\u5217.reduce(function(\u300c\u8a08\u7b97\u7d50\u679c\u300d,\u914d\u5217\u306e\u8981\u7d20){\r\n  return \u6b21\u306e\u30eb\u30fc\u30d7\u306e\u300c\u8a08\u7b97\u7d50\u679c\u300d\u306e\u5024;\r\n},\u300c\u8a08\u7b97\u7d50\u679c\u300d\u306e\u521d\u671f\u5024)<\/pre>\n<h3>\u4f8b<\/h3>\n<h4>\u6570\u5b57\u306e\u8a08\u7b97\u3092\u3059\u308b\u5834\u5408<\/h4>\n<pre class=\"lang:default decode:true\">let numbers = [1,2,3,5];\r\n\r\nnumbers.reduce(function(sum,number){\r\n  return sum + number;\r\n},0) \/\/11<\/pre>\n<h4>\u914d\u5217\u3092\u69cb\u7bc9\u3059\u308b\u5834\u5408<\/h4>\n<p>map\u3067\u3082\u540c\u69d8\u306e\u3053\u3068\u3092\u3082\u3063\u3068\u7c21\u6f54\u306b\u3067\u304d\u307e\u3059\u304c\u3001reduce\u3067\u3082\u5b9f\u88c5\u53ef\u80fd\u3067\u3059\u3002<\/p>\n<pre class=\"lang:default decode:true  \">let cats = [\r\n  { name:'\u592a\u90ce',kind:'\u4e09\u6bdb\u732b' },\r\n  { name:'\u82b1\u5b50',kind:'\u30da\u30eb\u30b7\u30e3\u732b' },\r\n  { name:'\u6b21\u90ce',kind:'\u4e09\u6bdb\u732b' }\r\n]\r\nlet kinds = cats.reduce(function(arr,cat){\r\n  arr.push(cat.kind);\r\n  return arr;\r\n},[]);\r\nkinds; \/\/[\"\u4e09\u6bdb\u732b\",\"\u30da\u30eb\u30b7\u30e3\u732b\",\"\u4e09\u6bdb\u732b\"]<\/pre>\n","protected":false},"excerpt":{"rendered":"map\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f \u65e2\u5b58\u306e\u914d\u5217\u3092\u52a0\u5de5\u3057\u3066\u65b0\u3057\u3044\u914d\u5217\u3092\u4f5c\u6210\u3059\u308b\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002 \u69cb\u6587 let \u65b0\u3057\u3044\u914d\u5217 = \u914d\u5217.map(function(\u914d\u5217\u306e\u8981\u7d20){ return \u914d\u5217\u306e\u8981\u7d20\u306e\u5024; }); \u30dd\u30a4\u30f3\u30c8 \u65e2\u5b58\u306e\u914d [&hellip;]","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[16],"tags":[],"_links":{"self":[{"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=\/wp\/v2\/posts\/10542"}],"collection":[{"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10542"}],"version-history":[{"count":14,"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=\/wp\/v2\/posts\/10542\/revisions"}],"predecessor-version":[{"id":20283,"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=\/wp\/v2\/posts\/10542\/revisions\/20283"}],"wp:attachment":[{"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10542"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10542"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.code-magagine.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10542"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}