{"id":104836,"date":"2016-06-02T19:54:16","date_gmt":"2016-06-02T10:54:16","guid":{"rendered":"http:\/\/www.key-p.com\/blog\/staff\/?p=104836"},"modified":"2016-06-03T11:35:03","modified_gmt":"2016-06-03T02:35:03","slug":"promise%e3%81%a8catch%e3%81%ae%e8%89%af%e3%81%84%e6%9b%b8%e3%81%8d%e6%96%b9","status":"publish","type":"post","link":"https:\/\/www.key-p.com\/blog\/staff\/archives\/104836","title":{"rendered":"Promise\u3068catch\u306e\u826f\u3044\u66f8\u304d\u65b9"},"content":{"rendered":"

\n\u4eca\u56de\u306f\u3001JavaScript\u306ePromise\u306b\u3064\u3044\u3066\u306e\u7d39\u4ecb\u3068\u3001Promise\u3092\u4f7f\u3063\u3066\u3044\u308b\u3068\u56f0\u308b\u300c\u4f8b\u5916\u6642\u306e\u30a8\u30e9\u30fc\u51fa\u529b\u300d\u306b\u3064\u3044\u3066\u66f8\u304d\u307e\u3059\u3002
\n

Promise\u3068\u306f<\/h3>\nPromise\u306f\u975e\u540c\u671f\u51e6\u7406\u3092\u5206\u304b\u308a\u3084\u3059\u304f\u8a18\u8ff0\u3059\u308b\u305f\u3081\u306b\u4f7f\u308f\u308c\u308b\u3082\u306e\u3067\u3059\u3002
\n
\n\u4f8b\u3048\u3070\u3001Node.js\u30673\u3064\u306e\u30d5\u30a1\u30a4\u30eb\u3092\u8aad\u307f\u8fbc\u3080\u3088\u3046\u306a\u5834\u5408\u3092\u8003\u3048\u307e\u3059\u3002\u3072\u3068\u3064\u524d\u306e\u30d5\u30a1\u30a4\u30eb\u306e\u5185\u5bb9\u3092\u4f7f\u3063\u3066\u6b21\u306e\u30d5\u30a1\u30a4\u30eb\u3092\u8aad\u307f\u8fbc\u3080\u30a4\u30e1\u30fc\u30b8\u3067\u3059\u3002
\n
\n\u3053\u306e\u5834\u5408\u3001readFileSync\u3092\u4f7f\u3046\u306a\u3069\u306e\u56de\u907f\u304c\u3067\u304d\u308b\u3068\u601d\u3044\u307e\u3059\u304c\u3001Promise\u306e\u8aac\u660e\u306e\u305f\u3081\u975e\u540c\u671f\u51e6\u7406\u3067\u884c\u3044\u307e\u3059\u3002
\n
\n\u307e\u305a\u306f\u3001Promise\u3092\u4f7f\u308f\u305a\u306b\u66f8\u3044\u3066\u307f\u307e\u3059\u3002
\n
const fs = require( 'fs' );\n\nfs.readFile( 'file1', function ( error, data1 ) {\n    \/\/ data1\u304b\u3089\u6b21\u306b\u8aad\u307f\u8fbc\u3080\u30d5\u30a1\u30a4\u30eb\u540d\u3092\u6c42\u3081\u308b\n    fs.readFile( data1, function ( error, data2 ) {\n        \/\/ data2\u304b\u3089\u6b21\u306b\u8aad\u307f\u8fbc\u3080\u30d5\u30a1\u30a4\u30eb\u540d\u3092\u6c42\u3081\u308b\n        fs.readFile( data2, function ( error, data3 ) {\n            \/\/ data3\u3092\u4f7f\u3063\u305f\u51e6\u7406\n        } );\n    } );\n} );<\/pre>\n\u3053\u306e\u3088\u3046\u306b\u975e\u540c\u671f\u51e6\u7406\u3067\u8aad\u307f\u8fbc\u307f\u3092\u884c\u304a\u3046\u3068\u3059\u308b\u3068\u3001\u30cd\u30b9\u30c8\u304c\u6df1\u304f\u306a\u308a\u898b\u3065\u3089\u3044\u3068\u3044\u3046\u6b20\u70b9\u304c\u3042\u308a\u307e\u3059\u3002
\n
\n\u305d\u3053\u3067\u3001Promise\u3092\u4f7f\u3046\u3068\u30cd\u30b9\u30c8\u3092\u6df1\u304f\u305b\u305a\u306b\u975e\u540c\u671f\u51e6\u7406\u3092\u8a18\u8ff0\u3067\u304d\u307e\u3059\u3002
\n
const fs = require( 'fs' );\n\n\/\/ readFile\u95a2\u6570\u306ePromise\u3092\u8fd4\u3059\u95a2\u6570\u3092\u4f5c\u6210\u3059\u308b\nfunction readFile( ...args ) {\n    return new Promise( function ( resolve, reject ) {\n        fs.readFile( ...args, function ( error, data ) {\n            if ( error ) reject( error );\n            else resolve( data );\n        } );\n    } );\n}\n\nreadFile( 'file1' ).then( function ( data1 ) {\n    \/\/ data1\u304b\u3089\u6b21\u306b\u8aad\u307f\u8fbc\u3080\u30d5\u30a1\u30a4\u30eb\u540d\u3092\u6c42\u3081\u308b\n    return readFile( data1 );\n} ).then( function ( data2 ) {\n    \/\/ data2\u304b\u3089\u6b21\u306b\u8aad\u307f\u8fbc\u3080\u30d5\u30a1\u30a4\u30eb\u540d\u3092\u6c42\u3081\u308b\n    return readFile( data2 );\n} ).then( function ( data3 ) {\n    \/\/ data3\u3092\u4f7f\u3063\u305f\u51e6\u7406\n} ).catch( function ( error ) {\n    \/\/ \u3044\u305a\u308c\u304b\u306ereadFile\u3067\u30a8\u30e9\u30fc\u304c\u3042\u3063\u305f\u5834\u5408\u306e\u51e6\u7406\n    console.log( error );\n} );<\/pre>\n\u6c17\u3092\u3064\u3051\u306a\u3051\u308c\u3070\u3044\u3051\u306a\u3044\u70b9\u3068\u3057\u3066\u3001catch\u306e\u8a18\u8ff0\u5fd8\u308c\u304c\u3042\u308a\u307e\u3059\u3002catch\u3067\u6307\u5b9a\u3057\u305f\u95a2\u6570\u306fPromise\u306e\u4e2d\u3067\u4f8b\u5916\u304c\u8d77\u304d\u305f\u5834\u5408\u306b\u547c\u3070\u308c\u307e\u3059\u3002
\n
\n\u3053\u308c\u3092\u8a18\u8ff0\u3057\u306a\u3044\u3068\u3001\u4f8b\u5916\u304c\u8d77\u304d\u305f\u3053\u3068\u3092\u77e5\u308b\u3059\u3079\u304c\u306a\u304f\u3001\u30b3\u30f3\u30bd\u30fc\u30eb\u306a\u3069\u306b\u3082\u306a\u306b\u3082\u51fa\u529b\u3055\u308c\u307e\u305b\u3093\u3002
\n
\u4f8b\u5916\u6642\u306e\u30a8\u30e9\u30fc\u51fa\u529b<\/h3>\ncatch\u3067\u4f8b\u5916\u3092\u77e5\u308b\u3053\u3068\u306f\u3067\u304d\u307e\u3059\u304c\u3001\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u3092\u901a\u5e38\u306e\u4f8b\u5916\u304c\u6295\u3052\u3089\u308c\u305f\u3068\u304d\u306e\u3088\u3046\u306b\u30b3\u30f3\u30bd\u30fc\u30eb\u3078\u51fa\u529b\u3059\u308b\u5834\u5408\u3001\u4e00\u5de5\u592b\u304c\u5fc5\u8981\u3067\u3059\u3002
\n
\nprocess.nextTick\u3082\u3057\u304f\u306fsetTimeout(\u3082\u3057\u304f\u306flodash\u306edefer)\u3092\u4f7f\u3046\u3053\u3068\u3067\u3001\u901a\u5e38\u306e\u3088\u3046\u306b\u30a8\u30e9\u30fc\u3092\u518d\u9001\u3067\u304d\u307e\u3059\u3002
\n
\n\u4ee5\u4e0b\u306e\u3088\u3046\u306bconsole.error\u3067\u51fa\u529b\u3057\u305f\u5834\u5408\u306f\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u304c\u8868\u793a\u3055\u308c\u306a\u3044\u305f\u3081\u3001\u30c7\u30d0\u30c3\u30b0\u3092\u3059\u308b\u3053\u3068\u304c\u96e3\u3057\u3044\u3067\u3059\u3002
\n
( new Promise( function ( resolve, reject ) {\n\tthrowFunc();\n} ) ).catch( outError );\n\nfunction throwFunc() {\n\tthrow new Error( 'error text.' );\n}\n\nfunction outError( error ) {\n\tconsole.error( error ); \/\/ [Error: error text.]\n}<\/pre>\n\u3053\u308c\u306b\u5bfe\u3057\u3066\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306bsetTimeout\u3092\u4f7f\u3046\u3053\u3068\u3067\u3001\u901a\u5e38\u306e\u4f8b\u5916\u767a\u751f\u6642\u3068\u540c\u3058\u3088\u3046\u306b\u3001\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u306e\u30a8\u30e9\u30fc\u3092\u8868\u793a\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002
\n
( new Promise( function ( resolve, reject ) {\n\tthrowFunc();\n} ) ).catch( timeoutThrow );\n\nfunction throwFunc() {\n\tthrow new Error( 'error text.' );\n}\n\nfunction timeoutThrow( error ) {\n\tsetTimeout( function () { throw error; } );\n}<\/pre>\n\u3053\u306e\u3088\u3046\u306a\u30a8\u30e9\u30fc\u51fa\u529b\u306b\u306a\u308a\u307e\u3059\u3002
\n
\/path\/to\/source.js:10\n    setTimeout( function () { throw error; } );\n                              ^\n\nError: error text.\n    at throwFunc (\/path\/to\/source.js:6:8)\n    at \/path\/to\/source.js:2:2\n    at Object. (\/path\/to\/source.js:1:65)\n    at Module._compile (module.js:413:34)\n    at Object.Module._extensions..js (module.js:422:10)\n    at Module.load (module.js:357:32)\n    at Function.Module._load (module.js:314:12)\n    at Function.Module.runMain (module.js:447:10)\n    at startup (node.js:142:18)\n    at node.js:939:3<\/pre>\n\u4ed6\u306b\u3082\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u95a2\u6570\u3067\u540c\u3058\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u5229\u7528\u3057\u3066\u3044\u308b\u30e9\u30a4\u30d6\u30e9\u30ea\u3084\u74b0\u5883\u306b\u5408\u308f\u305b\u3066\u4f7f\u3044\u5206\u3051\u3066\u304f\u3060\u3055\u3044\u3002
\n
\/\/ Node.js\u306enextTick\u3092\u4f7f\u3063\u305f\u5834\u5408\nfunction nextTickThrow( error ) {\n\tprocess.nextTick( function () { throw error; } );\n}\n\n\/\/ lodash\u3092\u4f7f\u3063\u305f\u5834\u5408\nfunction deferThrow( error ) {\n\t_.defer( function () { throw error; } );\n}<\/pre>\n\u8a73\u3057\u304fPromise\u306b\u3064\u3044\u3066\u77e5\u308a\u305f\u3044\u5834\u5408\u306f\u3001Promise - JavaScript | MDN<\/a>\u304c\u53c2\u8003\u306b\u306a\u308a\u307e\u3059\u3002
\n
\n
\n
\n
\n\u30ad\u30fc\u30fb\u30dd\u30a4\u30f3\u30c8\u3067\u306f\u3001
\n\u300c\u30cd\u30b9\u30c8\u6df1\u304f\u306a\u3063\u305f\u306a\u300d\u3067\u601d\u8003\u3092\u653e\u7f6e\u3057\u306a\u3044\u30a8\u30f3\u30b8\u30cb\u30a2\u3092\u52df\u96c6\u3057\u3066\u3044\u307e\u3059\u3002
\n\u30fb2017\u65b0\u5352\u306e\u65b9\u306f\u30ea\u30af\u30ca\u30d32017\u3078 ( \u7b2c2\u5f3e\u9078\u8003 \u30a8\u30f3\u30c8\u30ea\u30fc\u53d7\u4ed8\u4e2d\u3067\u3059 )<\/a>
\n\u30fb\u4e2d\u9014\u306e\u65b9\u306f\u30b3\u30c1\u30e9\u3078<\/a>
\n
\n
\n<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4eca\u56de\u306f\u3001JavaScript\u306ePromise\u306b\u3064\u3044\u3066\u306e\u7d39\u4ecb\u3068\u3001Promise\u3092\u4f7f … \u7d9a\u304d\u3092\u8aad\u3080 →<\/span><\/a><\/p>\n","protected":false},"author":40,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[16],"tags":[],"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts\/104836"}],"collection":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/users\/40"}],"replies":[{"embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/comments?post=104836"}],"version-history":[{"count":19,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts\/104836\/revisions"}],"predecessor-version":[{"id":104857,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts\/104836\/revisions\/104857"}],"wp:attachment":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/media?parent=104836"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/categories?post=104836"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/tags?post=104836"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}