{"id":6485,"date":"2026-05-21T13:48:21","date_gmt":"2026-05-21T04:48:21","guid":{"rendered":"https:\/\/route-zero.com\/recruit\/?post_type=route&p=6485"},"modified":"2026-10-21T13:48:27","modified_gmt":"2026-10-21T04:48:27","slug":"javascript-json-parse-unexpected-token-errors","status":"publish","type":"route","link":"https:\/\/route-zero.com\/recruit\/route\/6485\/","title":{"rendered":"JSON.parse\u306eUnexpected token\u3092\u5207\u308a\u5206\u3051\u308b\u624b\u9806"},"content":{"rendered":"

JavaScript\u306eJSON.parse\u3067\u300cUnexpected token\u300d\u306a\u3069\u306eSyntaxError\u304c\u51fa\u305f\u3089\u3001\u307e\u305a\u89e3\u6790\u5bfe\u8c61\u304c\u672c\u5f53\u306bJSON\u6587\u5b57\u5217\u304b\u3092\u78ba\u8a8d\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u539f\u56e0\u306f\u3001\u672b\u5c3e\u306e\u30ab\u30f3\u30de\u3001\u30b7\u30f3\u30b0\u30eb\u30af\u30a9\u30fc\u30c8\u3001\u30ad\u30fc\u306e\u30c0\u30d6\u30eb\u30af\u30a9\u30fc\u30c8\u4e0d\u8db3\u3001\u7a7a\u6587\u5b57\u3001API\u304b\u3089\u8fd4\u3063\u305fHTML\u306a\u3069\u306b\u5206\u304b\u308c\u307e\u3059\u3002API\u9023\u643a\u306a\u3089HTTP\u30b9\u30c6\u30fc\u30bf\u30b9\u30fbContent-Type\u30fb\u672c\u6587\u3092\u9806\u306b\u78ba\u8a8d\u3057\u3001\u69cb\u6587\u304c\u6b63\u3057\u3044JSON\u304b\u3069\u3046\u304b\u3068\u3001\u30c7\u30fc\u30bf\u306e\u4e2d\u8eab\u304c\u30a2\u30d7\u30ea\u306e\u60f3\u5b9a\u306b\u5408\u3046\u304b\u3092\u5207\u308a\u5206\u3051\u307e\u3057\u3087\u3046\u3002<\/p>\n

JSON.parse\u306eUnexpected token\u306f\u4f55\u3092\u793a\u3059\uff1f<\/h2>\n

JSON.parse\u306f\u3001\u5f15\u6570\u3092JSON\u3068\u3057\u3066\u8aad\u307f\u53d6\u308c\u306a\u3044\u5834\u5408\u306bSyntaxError\u3092\u6295\u3052\u307e\u3059\u3002\u6587\u8a00\u3084\u4f4d\u7f6e\u60c5\u5831\u306e\u8868\u793a\u306fJavaScript\u30a8\u30f3\u30b8\u30f3\u30fb\u74b0\u5883\u306b\u3088\u3063\u3066\u7570\u306a\u308a\u3001\u300cUnexpected token\u300d\u4ee5\u5916\u306e\u8868\u73fe\u306b\u306a\u308b\u3053\u3068\u3082\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n\n\n\n\n\n\n
\u30a8\u30e9\u30fc\u306b\u3064\u306a\u304c\u308b\u5165\u529b\u4f8b<\/th>\n\u4e3b\u306a\u539f\u56e0<\/th>\n\u78ba\u8a8d\u65b9\u6cd5<\/th>\n<\/tr>\n<\/thead>\n
{'name':'A'}<\/td>\n\u30b7\u30f3\u30b0\u30eb\u30af\u30a9\u30fc\u30c8\u3067JSON\u6587\u5b57\u5217\u3092\u56f2\u3080<\/td>\nJSON\u3067\u306f\u30c0\u30d6\u30eb\u30af\u30a9\u30fc\u30c8\u304c\u5fc5\u8981<\/td>\n<\/tr>\n
{name:"A"}<\/td>\n\u30d7\u30ed\u30d1\u30c6\u30a3\u540d\u306e\u5f15\u7528\u7b26\u304c\u306a\u3044<\/td>\n"name"\u306e\u5f62\u5f0f\u306b\u3059\u308b<\/td>\n<\/tr>\n
{"name":"A",}<\/td>\n\u672b\u5c3e\u306e\u30ab\u30f3\u30de<\/td>\n\u6700\u5f8c\u306e\u8981\u7d20\u306e\u76f4\u5f8c\u306e\u30ab\u30f3\u30de\u3092\u5916\u3059<\/td>\n<\/tr>\n
<html>…<\/html><\/td>\nHTML\u30ec\u30b9\u30dd\u30f3\u30b9\u3092JSON\u6271\u3044<\/td>\nAPI\u306e\u30b9\u30c6\u30fc\u30bf\u30b9\u3068\u672c\u6587\u7a2e\u985e\u3092\u8abf\u3079\u308b<\/td>\n<\/tr>\n
\u7a7a\u6587\u5b57\u5217<\/td>\n\u89e3\u6790\u53ef\u80fd\u306aJSON\u5024\u304c\u306a\u3044<\/td>\n\u30ec\u30b9\u30dd\u30f3\u30b9204\u306a\u3069\u3092\u533a\u5225\u3059\u308b<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

\u7528\u8a9e\u89e3\u8aac\uff1aSyntaxError<\/strong>
JavaScript\u304c\u898f\u5b9a\u306e\u69cb\u6587\u3068\u3057\u3066\u8aad\u307f\u53d6\u308c\u306a\u3044\u3068\u304d\u306b\u51fa\u308b\u30a8\u30e9\u30fc\u578b\u3002JSON.parse\u3067\u306f\u53d7\u4fe1\u30c6\u30ad\u30b9\u30c8\u304cJSON\u6587\u6cd5\u306b\u5408\u308f\u306a\u3044\u5834\u5408\u306b\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n<\/blockquote>\n

\n

\u624b\u98061\uff1a\u3069\u306e\u6587\u5b57\u5217\u3092parse\u3057\u3066\u3044\u308b\u304b\u7279\u5b9a\u3059\u308b<\/h2>\n

\u30a2\u30d7\u30ea\u306e\u3069\u3053\u3067JSON.parse\u304c\u547c\u3070\u308c\u305f\u304b\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u3092\u78ba\u8a8d\u3057\u3001\u76f4\u524d\u306b\u6e21\u3057\u305f\u5024\u306e\u7a2e\u985e\u3092\u30c1\u30a7\u30c3\u30af\u3057\u307e\u3059\u3002\u5b9f\u30b5\u30fc\u30d3\u30b9\u3067\u306f\u5165\u529b\u672c\u6587\u3092\u305d\u306e\u307e\u307e\u30ed\u30b0\u3078\u51fa\u3059\u3068\u8a8d\u8a3c\u60c5\u5831\u30fb\u500b\u4eba\u60c5\u5831\u304c\u6df7\u3056\u308b\u3053\u3068\u304c\u3042\u308b\u305f\u3081\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n

function parseJsonSafely(raw) {\r\n  if (typeof raw !== "string") {\r\n    throw new TypeError("JSON\u7528\u306e\u6587\u5b57\u5217\u3092\u6307\u5b9a\u3057\u3066\u304f\u3060\u3055\u3044");\r\n  }\r\n\r\n  try {\r\n    return JSON.parse(raw);\r\n  } catch (error) {\r\n    if (error instanceof SyntaxError) {\r\n      throw new Error("JSON\u5f62\u5f0f\u306e\u5165\u529b\u3067\u306f\u3042\u308a\u307e\u305b\u3093", {\r\n        cause: error\r\n      });\r\n    }\r\n    throw error;\r\n  }\r\n}<\/code><\/pre>\n
\u3053\u306e\u4f8b\u306f\u539f\u56e0\u3092\u5224\u5225\u3059\u308b\u5165\u53e3\u3067\u3059\u3002\u5b9f\u52d9\u3067\u306f\u3001\u5165\u529b\u7a2e\u5225\u30fb\u9577\u3055\u30fb\u51e6\u7406\u306e\u767a\u751f\u7b87\u6240\u306a\u3069\u3001\u6a5f\u5fae\u60c5\u5831\u3092\u542b\u307e\u306a\u3044\u60c5\u5831\u3092\u8a18\u9332\u3057\u3001\u672c\u6587\u5168\u4f53\u3092\u7121\u6761\u4ef6\u306b\u30ed\u30b0\u51fa\u529b\u3057\u306a\u3044\u3088\u3046\u306b\u3057\u307e\u3059\u3002<\/p>\n
\n
\u624b\u98062\uff1aJSON\u6587\u6cd5\u3092\u898b\u76f4\u3059<\/h2>\n
\u6700\u3082\u4e00\u822c\u7684\u306a\u306e\u306f\u3001JavaScript\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u3057\u3066\u306f\u898b\u6163\u308c\u305f\u8a18\u6cd5\u3092JSON\u6587\u5b57\u5217\u3078\u4f7f\u3063\u3066\u3057\u307e\u3046\u3053\u3068\u3067\u3059\u3002\u5c0f\u3055\u306a\u5165\u529b\u4f8b\u3067\u6bd4\u3079\u308b\u3068\u9055\u3044\u304c\u5206\u304b\u308a\u307e\u3059\u3002<\/p>\n
\/\/ JavaScript\u306e\u6587\u5b57\u5217\u3068\u3057\u3066\u6b63\u3057\u3044\u304cJSON\u3068\u3057\u3066\u306f\u4e0d\u6b63\r\nconst invalid = "{'name': 'A',}";\r\ntry {\r\n  JSON.parse(invalid);\r\n} catch (error) {\r\n  console.log(error instanceof SyntaxError); \/\/ true\r\n}\r\n\r\nconst valid = '{"name": "A"}';\r\nconsole.log(JSON.parse(valid).name); \/\/ A<\/code><\/pre>\n
JSON\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u540d\u3068\u6587\u5b57\u5217\u5024\u306f\u30c0\u30d6\u30eb\u30af\u30a9\u30fc\u30c8\u3067\u56f2\u307f\u3001\u672b\u5c3e\u306e\u30ab\u30f3\u30de\u3092\u4ed8\u3051\u307e\u305b\u3093\u3002JavaScript\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30ea\u30c6\u30e9\u30eb\u3068JSON\u6587\u5b57\u5217\u306f\u540c\u3058\u6587\u6cd5\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n\n\n\n\n\n\n\n\n\n
\u8aa4\u308a\u306e\u4f8b<\/th>\n\u76f4\u3057\u65b9<\/th>\n<\/tr>\n<\/thead>\n
\u30b7\u30f3\u30b0\u30eb\u30af\u30a9\u30fc\u30c8\u306e\u6587\u5b57\u5217<\/td>\nJSON\u5185\u90e8\u3092\u30c0\u30d6\u30eb\u30af\u30a9\u30fc\u30c8\u3078<\/td>\n<\/tr>\n
\u672b\u5c3e\u306e\u30ab\u30f3\u30de<\/td>\n\u4f59\u8a08\u306a\u30ab\u30f3\u30de\u3092\u53d6\u308a\u9664\u304f<\/td>\n<\/tr>\n
undefined\u3084NaN<\/td>\nJSON\u3068\u3057\u3066\u8a31\u3055\u308c\u308b\u5024\u3078\u5909\u63db\u3059\u308b<\/td>\n<\/tr>\n
JavaScript\u30b3\u30e1\u30f3\u30c8<\/td>\n\u30b3\u30e1\u30f3\u30c8\u3092\u9664\u53bb\u3059\u308b<\/td>\n<\/tr>\n
\u8907\u6570\u306eJSON\u5024\u3092\u9023\u7d50<\/td>\n1\u3064\u306eJSON\u30c7\u30fc\u30bf\u3068\u3057\u3066\u8a2d\u8a08\u3059\u308b<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n
\u624b\u98063\uff1a\u300cUnexpected token <\u300d\u306a\u3089HTML\u30ec\u30b9\u30dd\u30f3\u30b9\u3092\u7591\u3046<\/h2>\n
API\u306eJSON\u3092\u53d7\u3051\u53d6\u308b\u3064\u3082\u308a\u304c\u30ed\u30b0\u30a4\u30f3\u753b\u9762\u30fb404\u30da\u30fc\u30b8\u30fb\u30b5\u30fc\u30d0\u30fc\u30a8\u30e9\u30fc\u306eHTML\u3092\u53d7\u4fe1\u3057\u3066\u3044\u305f\u5834\u5408\u3001\u5148\u982d\u306b\u30bf\u30b0\u306e\u8a18\u53f7\u304c\u73fe\u308c\u3001JSON\u3068\u3057\u3066\u89e3\u6790\u3067\u304d\u307e\u305b\u3093\u3002\u30a8\u30e9\u30fc\u6587\u5b57\u5217\u306e\u300c<\u300d\u306f\u4e00\u4f8b\u3067\u3042\u308a\u3001\u5fc5\u305a\u3053\u306e\u6587\u8a00\u306b\u306a\u308b\u3068\u306f\u9650\u308a\u307e\u305b\u3093\u3002<\/p>\n
const response = await fetch("\/api\/users");\r\n\r\nif (!response.ok) {\r\n  throw new Error("HTTP " + response.status);\r\n}\r\n\r\nconst contentType = response.headers.get("content-type") ?? "";\r\n\r\nif (!contentType.toLowerCase().includes("json")) {\r\n  throw new Error("JSON\u3067\u306a\u3044\u5fdc\u7b54\u304c\u8fd4\u308a\u307e\u3057\u305f");\r\n}\r\n\r\nconst data = await response.json();\r\nconsole.log(Array.isArray(data));<\/code><\/pre>\n
response.json()\u306e\u5185\u90e8\u3067\u3082JSON\u306e\u89e3\u6790\u304c\u884c\u308f\u308c\u307e\u3059\u3002\u8fd4\u3063\u3066\u304d\u305fHTTP\u30b9\u30c6\u30fc\u30bf\u30b9\u3068Content-Type\u3092\u5148\u306b\u898b\u308b\u3053\u3068\u3067\u3001API\u304cJSON\u3067\u306f\u306a\u3044\u5fdc\u7b54\u3092\u8fd4\u3057\u305f\u539f\u56e0\u3092\u8abf\u3079\u3084\u3059\u304f\u306a\u308a\u307e\u3059\u3002Content-Type\u306f\u81ea\u5df1\u7533\u544a\u306a\u306e\u3067\u3001JSON\u3068\u66f8\u304b\u308c\u3066\u3044\u3066\u3082\u672c\u6587\u307e\u3067\u6b63\u3057\u3044\u3068\u306f\u9650\u308a\u307e\u305b\u3093\u3002<\/p>\n
\u3053\u308c\u306fJSON\u5fdc\u7b54\u3092\u5fc5\u9808\u3068\u3059\u308bAPI\u5411\u3051\u306e\u30ac\u30fc\u30c9\u4f8b\u3067\u3059\u3002Content-Type\u304c\u7701\u7565\u3055\u308c\u305fAPI\u3084\u72ec\u81ea\u30e1\u30c7\u30a3\u30a2\u30bf\u30a4\u30d7\u3067\u306f\u3001\u5951\u7d04\u306b\u5408\u308f\u305b\u3066\u5224\u5b9a\u6761\u4ef6\u3092\u8abf\u6574\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
\u624b\u98064\uff1a204\u3084\u7a7a\u672c\u6587\u3092JSON.parse\u3078\u6e21\u3055\u306a\u3044<\/h2>\n
API\u304c204 No Content\u3092\u8fd4\u3057\u305f\u5834\u5408\u306f\u3001\u6b63\u5e38\u7d42\u4e86\u3067\u3082\u5fdc\u7b54\u672c\u6587\u304c\u3042\u308a\u307e\u305b\u3093\u3002\u7a7a\u6587\u5b57\u306b\u5bfe\u3057\u3066JSON.parse\u3084response.json\u3092\u547c\u3076\u3068SyntaxError\u306b\u306a\u308b\u305f\u3081\u3001\u672c\u6587\u304c\u5fc5\u8981\u306aAPI\u304b\u3069\u3046\u304b\u3092\u5148\u306b\u5224\u65ad\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n
async function loadItems() {\r\n  const response = await fetch("\/api\/items");\r\n\r\n  if (!response.ok) {\r\n    throw new Error("HTTP " + response.status);\r\n  }\r\n\r\n  if (response.status === 204) {\r\n    return null;\r\n  }\r\n\r\n  const body = await response.text();\r\n\r\n  if (body.trim().length === 0) {\r\n    throw new Error("JSON\u672c\u6587\u304c\u7a7a\u3067\u3057\u305f");\r\n  }\r\n\r\n  return JSON.parse(body);\r\n}<\/code><\/pre>\n
\u4e00\u5ea6response.text()\u3067\u8aad\u3093\u3060\u672c\u6587\u306f\u3001\u540c\u3058Response\u304b\u3089\u3082\u3046\u4e00\u5ea6response.json()\u3067\u8aad\u3080\u3053\u3068\u306f\u901a\u5e38\u3067\u304d\u307e\u305b\u3093\u3002\u3069\u3061\u3089\u304b\u4e00\u65b9\u3092\u9078\u3093\u3067\u304f\u3060\u3055\u3044\u3002\u3053\u306e\u4f8b\u306f\u7a7a\u672c\u6587\u3092\u5225\u306e\u30a8\u30e9\u30fc\u3078\u5207\u308a\u5206\u3051\u308b\u8a2d\u8a08\u3067\u3001\u5b9f\u969b\u306eAPI\u4ed5\u69d8\u306b\u5408\u308f\u305b\u3066null\u3084\u30a8\u30e9\u30fc\u3092\u9078\u3073\u307e\u3059\u3002<\/p>\n
\u624b\u98065\uff1a\u69cb\u6587\u30a8\u30e9\u30fc\u3068\u30c7\u30fc\u30bf\u306e\u578b\u9055\u3044\u3092\u5206\u3051\u308b<\/h2>\n
JSON.parse\u3067\u30a8\u30e9\u30fc\u304c\u51fa\u306a\u3051\u308c\u3070\u3001\u305d\u308c\u306f\u300c\u69cb\u6587\u3068\u3057\u3066\u6b63\u3057\u3044JSON\u3060\u3063\u305f\u300d\u3068\u3044\u3046\u610f\u5473\u3067\u3059\u3002\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306ename\u304c\u6587\u5b57\u5217\u3067\u3042\u308b\u3001items\u304c\u914d\u5217\u3067\u3042\u308b\u3001\u3068\u3044\u3063\u305f\u30a2\u30d7\u30ea\u56fa\u6709\u306e\u6761\u4ef6\u307e\u3067\u4fdd\u8a3c\u3057\u307e\u305b\u3093\u3002<\/p>\n
const value = JSON.parse('{"items": [1, 2, 3]}');\r\n\r\nif (\r\n  typeof value !== "object" ||\r\n  value === null ||\r\n  !Array.isArray(value.items)\r\n) {\r\n  throw new Error("items\u304c\u914d\u5217\u3067\u306f\u3042\u308a\u307e\u305b\u3093");\r\n}\r\n\r\nconsole.log(value.items.length);<\/code><\/pre>\n
\u5229\u7528\u3059\u308b\u30c7\u30fc\u30bf\u304c\u5916\u90e8API\u7531\u6765\u306e\u5834\u5408\u306f\u3001\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u30b9\u30ad\u30fc\u30de\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u30e9\u30a4\u30d6\u30e9\u30ea\u3084\u660e\u793a\u7684\u306a\u578b\u691c\u67fb\u3092\u5c0e\u5165\u3057\u3001\u69cb\u6587\u30c1\u30a7\u30c3\u30af\u3068\u30c7\u30fc\u30bf\u691c\u8a3c\u3092\u5206\u96e2\u3057\u307e\u3059\u3002<\/p>\n
\u5b9f\u52d9\u3067\u591a\u3044\u539f\u56e0\u3068\u8a3a\u65ad\u9806<\/h2>\n