{"id":214,"date":"2023-07-25T09:49:55","date_gmt":"2023-07-25T01:49:55","guid":{"rendered":"https:\/\/www.hyw.life\/?p=214"},"modified":"2023-07-25T09:55:20","modified_gmt":"2023-07-25T01:55:20","slug":"6%e7%a7%8djavascript%e5%88%a4%e6%96%ad%e6%95%b0%e7%bb%84%e6%98%af%e5%90%a6%e5%8c%85%e5%90%ab%e6%9f%90%e4%b8%aa%e5%80%bc%e7%9a%84%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/www.hyw.life\/?p=214","title":{"rendered":"6\u79cdJavaScript\u5224\u65ad\u6570\u7ec4\u662f\u5426\u5305\u542b\u67d0\u4e2a\u503c\u7684\u65b9\u6cd5"},"content":{"rendered":"\n

\u6211\u4eec\u5728\u9879\u76ee\u5f00\u53d1\u8fc7\u7a0b\u4e2d\uff0c\u7ecf\u5e38\u4f1a\u8981\u68c0\u67e5\u4e00\u4e2a\u6570\u7ec4(\u65e0\u5e8f)\u662f\u5426\u5305\u542b\u4e00\u4e2a\u7279\u5b9a\u7684\u503c\uff1f\u8fd9\u662f\u4e00\u4e2a\u5728JavaScript\u4e2d\u7ecf\u5e38\u7528\u5230\u7684\u5e76\u4e14\u975e\u5e38\u6709\u7528\u7684\u64cd\u4f5c\u3002<\/p>\n\n\n\n

\u4e0b\u9762\u7ed9\u51fa\u51e0\u79cd\u5b9e\u73b0\u65b9\u5f0f\u3002<\/p>\n\n\n\n<\/span>

<\/a>\u65b9\u5f0f\u4e00\uff1a\u5229\u7528\u5faa\u73af<\/strong><\/h3>\n\n\n\n

\u8fd9\u79cd\u65b9\u5f0f\u662f\u6bd4\u8f83\u8001\u7684\u5b9e\u73b0\u65b9\u6848\uff0c\u4f46\u4e0d\u53ef\u5426\u8ba4\u7684\u662f\u5728\u6d4f\u89c8\u5668\u4e2d\u6548\u7387\u8f83\u9ad8\u3002<\/p>\n\n\n\n

function contains(arr, val) {\r\n  for (var i = 0; i < arr.length; i++) {\r\n    if (arr[i] === val) {\r\n      return true;\r\n    }\r\n  }\r\n  return false;\r\n}\r\ncontains([1, 2, 3], 3); \/\/true<\/code><\/pre>\n\n\n\n
\u6216\u8005\u4f7f\u7528while\uff1a<\/p>\n\n\n\n
function contains(arr, val) {\r\n  var i = arr.length;\r\n  while (i--) {\r\n    if (arr[i] === val) {\r\n      return true;\r\n    }\r\n  }\r\n  return false;\r\n}<\/code><\/pre>\n\n\n\n<\/span>
<\/a>\u65b9\u5f0f\u4e8c\uff1a\u4f7f\u7528\u6570\u7ec4\u7684some\uff0cfilter\u7b49\u65b9\u6cd5<\/strong><\/h3>\n\n\n\n
\u4f7f\u7528some\u65b9\u6cd5\u66f4\u7b80\u6d01\uff0c\u4e00\u65e6\u627e\u5230\u5143\u7d20\uff0c\u8fed\u4ee3\u5c31\u4f1a\u4e2d\u6b62\uff0c\u4ece\u800c\u907f\u514d\u4e86\u4e0d\u5fc5\u8981\u7684\u8fed\u4ee3\u5468\u671f\u3002<\/p>\n\n\n\n
function contains(arr, val) {\r\n  return arr.some((item) => item === val);\r\n}<\/code><\/pre>\n\n\n\n
\u4f7f\u7528filter\uff08\u6ce8\u610f\uff1aarray.filter(e=>e==x).length > 0\u7b49\u6548\u4e8earray.some(e=>e==x)\u4f46some\u66f4\u6709\u6548\uff09<\/p>\n\n\n\n
function contains(arr, val) {\r\n  return (\r\n    arr.filter((item) => {\r\n      return item == val;\r\n    }).length > 0\r\n  );\r\n}<\/code><\/pre>\n\n\n\n<\/span>
<\/a>\u65b9\u5f0f\u4e09\uff1aarray.indexOf<\/strong><\/h3>\n\n\n\n
array.indexOf\u6b64\u65b9\u6cd5\u5224\u65ad\u6570\u7ec4\u4e2d\u662f\u5426\u5b58\u5728\u67d0\u4e2a\u503c\uff0c\u5982\u679c\u5b58\u5728\u8fd4\u56de\u6570\u7ec4\u5143\u7d20\u7684\u4e0b\u6807\uff0c\u5426\u5219\u8fd4\u56de-1\u3002<\/p>\n\n\n\n
[1, 2, 3].indexOf(1); \/\/0\r\n[\"foo\", \"fly63\", \"baz\"].indexOf(\"fly63\"); \/\/1\r\n[1, 2, 3].indexOf(4); \/\/-1<\/code><\/pre>\n\n\n\n
\u6ce8\u610f\u70b9\uff1a<\/p>\n\n\n\n
\n
1\u3001indexOf() \u65b9\u6cd5\u5bf9\u5927\u5c0f\u5199\u654f\u611f\uff01\u5982\u679c\u8981\u68c0\u7d22\u7684\u5b57\u7b26\u4e32\u503c\u6ca1\u6709\u51fa\u73b0\uff0c\u5219\u8be5\u65b9\u6cd5\u8fd4\u56de -1\u3002
2\u3001\u5728\u6bd4\u8f83\u7b2c\u4e00\u4e2a\u53c2\u6570\u4e0e\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e00\u9879\u65f6\uff0c\u4f1a\u4f7f\u7528\u5168\u7b49\u64cd\u4f5c\u7b26\uff0c\u5373\u8981\u6c42\u67e5\u627e\u7684\u9879\u5fc5\u987b\u4e25\u683c\u76f8\u7b49
3\u3001\u6570\u7ec4\u7684\u4f4d\u7f6e\u662fECMAScript5\u4e3a\u6570\u7ec4\u5b9e\u4f8b\u65b0\u589e\u7684\uff0c\u652f\u6301\u7684\u6d4f\u89c8\u5668\u6709IE9+,Firefox,Safari,Opera,Chrome<\/p>\n<\/blockquote>\n\n\n\n<\/span>
<\/a>\u65b9\u5f0f\u56db\uff1aarray.includes<\/strong><\/h3>\n\n\n\n
array.includes(searchElement[, fromIndex]) \u6b64\u65b9\u6cd5\u5224\u65ad\u6570\u7ec4\u4e2d\u662f\u5426\u5b58\u5728\u67d0\u4e2a\u503c\uff0c\u5982\u679c\u5b58\u5728\u8fd4\u56de true\uff0c\u5426\u5219\u8fd4\u56defalse\u3002<\/p>\n\n\n\n
\u5b83\u53ef\u4ee5\u50cf\u8fd9\u6837\u4f7f\u7528\uff1a<\/p>\n\n\n\n
[1, 2, 3].includes(2); \/\/ true\n[1, 2, 3].includes(4); \/\/ false<\/code><\/pre>\n\n\n\n
\u5b83\u8fd8\u63a5\u53d7\u53ef\u9009\u7684\u7b2c\u4e8c\u4e2a\u53c2\u6570fromIndex\uff1a<\/p>\n\n\n\n
[1, 2, 3].includes(3, 3); \/\/ false\n[1, 2, 3].includes(3, -1); \/\/ true<\/code><\/pre>\n\n\n\n
\u4e0d\u50cfindexOf\uff0c\u5b83\u91c7\u7528\u4e25\u683c\u76f8\u7b49\u6bd4\u8f83\u3002\u8fd9\u610f\u5473\u7740\u60a8\u53ef\u4ee5\u68c0\u6d4b\u6570\u7ec4\u662f\u5426\u5305\u542bNaN\uff1a<\/p>\n\n\n\n
[1, 2, NaN].includes(NaN); \/\/ true<\/code><\/pre>\n\n\n\n
\u4e5f\u4e0d\u540c\u4e8eindexOf\uff0cincludes\u4e0d\u4f1a\u8df3\u8fc7\u7f3a\u5931\u7684\u7d22\u5f15\uff1a<\/p>\n\n\n\n
new Array(5).includes(undefined); \/\/ true<\/code><\/pre>\n\n\n\n<\/span>
<\/a>\u65b9\u5f0f\u4e94\uff1aarray.find<\/strong><\/h3>\n\n\n\n
find\u7528\u4e8e\u8fd4\u56de\u6570\u7ec4\u4e2d\u6ee1\u8db3\u6761\u4ef6\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u7684\u503c\uff0c\u5982\u679c\u6ca1\u6709\uff0c\u8fd4\u56deundefined\uff0c\u6bd4\u5982\uff1a<\/p>\n\n\n\n
let numbers = [12, 5, 8, 130, 44];\r\nlet result = numbers.find((item) => {\r\n  return item > 8;\r\n});\r\nconsole.log(result); \/\/12\/\/\u5143\u7d20\u662f\u5bf9\u8c61\r\nlet items = [\r\n  { id: 1, name: \"something\" },\r\n  { id: 2, name: \"anything\" },\r\n  { id: 3, name: \"nothing\" }\r\n];\r\nlet item = items.find((item) => {\r\n  return item.id == 3;\r\n});\r\nconsole.log(item);\r\n\/\/Object { id: 3, name: \"nothing\" }<\/code><\/pre>\n\n\n\n
\u9664\u4e86find\uff0c\u6211\u4eec\u4e5f\u53ef\u4ee5\u4f7f\u7528array.indIndex\u3002\u8fd4\u56de\u6570\u7ec4\u4e2d\u6ee1\u8db3\u6761\u4ef6\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u7684\u7d22\u5f15\uff08\u4e0b\u6807\uff09, \u5982\u679c\u6ca1\u6709\u627e\u5230\uff0c\u8fd4\u56de-1 \u540c\u7b2c3\u79cd\u65b9\u6cd5\u7c7b\u4f3c\u3002<\/p>\n\n\n\n<\/span>
<\/a>\u65b9\u5f0f\u516d\u3001\u5229\u7528set\u4e2dhas\u65b9\u6cd5<\/strong><\/h3>\n\n\n\n
function contains(arr, val) {\r\n  return new Set(arr).has(val);\r\n}\r\ncontains([1, 2, 3], 2); \/\/true<\/code><\/pre>\n\n\n\n
\u901a\u8fc7new set([])\u5c06\u6570\u7ec4\u8f6c\u6362\u6210Set\u5bf9\u8c61,set.prototype.has(value)\u5224\u65ad\u8be5\u503c\u662f\u5426\u5b58\u5728\u4e8eSet\u5bf9\u8c61\u4e2d\uff0c\u8fd4\u56de\u5e03\u5c14\u503c\u3002<\/p>\n\n\n\n
\u5ef6\u4f38\uff1a\u9664\u6b64\u4e4b\u5916\uff0c\u8fd8\u53ef\u4ee5\u5229\u7528\u5b83\u8fdb\u884c\u6570\u7ec4\u53bb\u91cd\uff0c\u6bd4\u5982\uff1a<\/p>\n\n\n\n
let arr2 = new Set([1,1,2,3,4])\r\nlet arr3 = [...arr2]\r\nconsole.log(arr2, arr3) \n\/\/ {1,2,3,4} [1,2,3,4]<\/code><\/pre>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
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