const user = {<\/p>\n name: "John Doe",<\/p>\n
contact: {<\/p>\n
email: "johndoe@example.com",<\/p>\n
phone: {<\/p>\n
home: "123-456-7890",<\/p>\n
work: "098-765-4321"<\/p>\n
}<\/p>\n
}<\/p>\n
};<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u901a\u5e38\u4f60\u53ef\u80fd\u9700\u8981\u8fd9\u6837\u83b7\u53d6\u7535\u8bdd\u53f7\u7801:<\/p>\n<\/p>\n
const homePhone = user.contact.phone.home;<\/p>\nconst workPhone = user.contact.phone.work;<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5229\u7528\u7ed3\u6784\u5316\u5206\u914d\uff0c\u4e0a\u8ff0\u8fc7\u7a0b\u53ef\u4ee5\u4f18\u96c5\u5730\u8f6c\u6362\u4e3a:<\/p>\n<\/p>\n
const { contact: { phone: { home: homePhone, work: workPhone } } } = user;<\/p>\n<\/code><\/pre>\n<\/p>\n
\u7ed3\u6784\u5316\u5206\u914d\u8fd9\u79cd\u65b9\u5f0f\u51cf\u5c11\u4e86\u4ee3\u7801\u91cd\u590d\uff0c\u5e76\u4e14\u4f7f\u4ee3\u7801\u66f4\u52a0\u4e00\u76ee\u4e86\u7136\u3002<\/p>\n<\/p>\n
\u4e8c\u3001\u4f7f\u7528?.<\/code>\u8fd0\u7b97\u7b26\uff08OPTIONAL CHAINING\uff09<\/h3>\n<\/p>\n\u968f\u7740ECMAScript 2020 (ES11)\u7684\u52a0\u5165\uff0cJavaScript\u63d0\u4f9b\u4e86\u4e00\u4e2a\u65b0\u7684\u7279\u6027\uff1aOptional Chaining\u3002\u4f7f\u7528?.<\/code>\u8fd0\u7b97\u7b26\u53ef\u4ee5\u4f18\u96c5\u5730\u5224\u65ad\u591a\u5c42\u7ea7\u5bf9\u8c61\u5c5e\u6027\u662f\u5426\u5b58\u5728\uff0c\u907f\u514d\u5728\u5c5e\u6027\u4e0d\u5b58\u5728\u65f6\u5bfc\u81f4\u7684\u9519\u8bef\u3002<\/p>\n<\/p>\n\u5728\u6ca1\u6709Optional Chaining\u4e4b\u524d\uff0c\u8bbf\u95ee\u5d4c\u5957\u5bf9\u8c61\u7684\u5c5e\u6027\u53ef\u80fd\u9700\u8981\u8fdb\u884c\u591a\u6b21\u7684\u5224\u7a7a\u64cd\u4f5c\uff1a<\/p>\n<\/p>\n
if (user && user.contact && user.contact.phone) {<\/p>\n const homePhone = user.contact.phone.home;<\/p>\n
}<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u73b0\u5728\uff0c\u4f7f\u7528?.<\/code>\u8fd0\u7b97\u7b26\uff0c\u53ef\u4ee5\u7b80\u5355\u5730\u8fd9\u6837\u5199\uff1a<\/p>\n<\/p>\nconst homePhone = user.contact?.phone?.home;<\/p>\n<\/code><\/pre>\n<\/p>\n
\u53ea\u6709\u5f53user<\/code>\u3001user.contact<\/code>\u4ee5\u53causer.contact.phone<\/code>\u90fd\u5b58\u5728\u65f6\uff0chomePhone<\/code>\u624d\u4f1a\u88ab\u8d4b\u503c\uff0c\u5927\u5927\u7b80\u5316\u4e86\u4ee3\u7801\u3002<\/p>\n<\/p>\n\u4e09\u3001\u4f7f\u7528?.<\/code>\u4e0e??<\/code>\u8fd0\u7b97\u7b26\uff08NULLISH COALESCING\uff09<\/h3>\n<\/p>\n\u7ed3\u5408Optional Chaining\u548cNullish Coalescing\u8fd0\u7b97\u7b26??<\/code>\uff0c\u4f60\u53ef\u4ee5\u5728\u67e5\u8be2\u4e0d\u5230\u5c5e\u6027\u503c\u65f6\u63d0\u4f9b\u4e00\u4e2a\u9ed8\u8ba4\u503c\u3002\u8fd9\u5728\u5904\u7406\u53ef\u80fd\u672a\u5b9a\u4e49\u7684\u5d4c\u5957\u5c5e\u6027\u65f6\u975e\u5e38\u6709\u7528\u3002<\/p>\n<\/p>\n\u4f8b\u5982\uff0c\u5982\u679c\u6211\u4eec\u60f3\u8981\u83b7\u53d6\u7528\u6237\u7684\u5bb6\u5ead\u7535\u8bdd\uff0c\u4f46\u662f\u5982\u679c\u8be5\u5b57\u6bb5\u672a\u5b9a\u4e49\uff0c\u5e0c\u671b\u8fd4\u56de\u4e00\u4e2a\u9ed8\u8ba4\u503c\uff1a<\/p>\n<\/p>\n
const homePhone = user.contact?.phone?.home ?? 'No Home Phone';<\/p>\n<\/code><\/pre>\n<\/p>\n
\u8fd9\u91cc\uff0c\u5982\u679chome<\/code>\u4e3anull<\/code>\u6216undefined<\/code>\uff0c\u5219homePhone<\/code>\u5c06\u88ab\u8bbe\u7f6e\u4e3a'No Home Phone'\u3002<\/p>\n<\/p>\n\u56db\u3001\u51fd\u6570\u5c01\u88c5<\/h3>\n<\/p>\n
\u6709\u65f6\u5019\uff0c\u5373\u4fbf\u662f\u4e0a\u8ff0\u4f18\u96c5\u7684\u65b9\u6cd5\u4e5f\u672a\u5fc5\u80fd\u6ee1\u8db3\u9700\u6c42\uff0c\u7279\u522b\u662f\u5f53\u4f60\u9700\u8981\u5bf9\u5c5e\u6027\u8bbf\u95ee\u903b\u8f91\u8fdb\u884c\u590d\u7528\u65f6\u3002\u8fd9\u65f6\uff0c\u4f60\u53ef\u4ee5\u5c06\u5c5e\u6027\u8bbf\u95ee\u903b\u8f91\u5c01\u88c5\u5230\u4e00\u4e2a\u51fd\u6570\u4e2d\u3002<\/p>\n<\/p>\n
\u4f8b\u5982\uff0c\u83b7\u5f97\u7528\u6237\u7684\u5bb6\u5ead\u7535\u8bdd\u8fd9\u4e00\u903b\u8f91\u53ef\u4ee5\u5c01\u88c5\u6210\uff1a<\/p>\n<\/p>\n
function getHomePhone(user) {<\/p>\n return user.contact?.phone?.home ?? 'No Home Phone';<\/p>\n
}<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u6837\uff0c\u6bcf\u6b21\u9700\u8981\u83b7\u53d6\u5bb6\u5ead\u7535\u8bdd\u65f6\uff0c\u53ea\u9700\u8c03\u7528getHomePhone(user)<\/code>\u5373\u53ef\u3002<\/p>\n<\/p>\n\u4e94\u3001\u4f7f\u7528\u5e93\u548c\u5de5\u5177<\/h3>\n<\/p>\n
\u9664\u4e86\u539f\u751f\u7684JavaScript\u63d0\u4f9b\u7684\u65b9\u6cd5\uff0c\u6709\u65f6\u5019\u4f60\u4e5f\u53ef\u4ee5\u4f7f\u7528\u4e00\u4e9b\u5e93\u6765\u7b80\u5316\u6df1\u5c42\u5c5e\u6027\u7684\u8bbf\u95ee\u3002\u4f8b\u5982\uff0clodash<\/code>\u5e93\u7684_.get()<\/code>\u51fd\u6570\u53ef\u4ee5\u5b89\u5168\u5730\u8bbf\u95ee\u6df1\u5d4c\u5957\u7684\u8def\u5f84\uff0c\u5e76\u5141\u8bb8\u8bbe\u7f6e\u4e00\u4e2a\u9ed8\u8ba4\u503c\u6765\u5904\u7406\u672a\u5b9a\u4e49\u7684\u60c5\u51b5\u3002<\/p>\n<\/p>\n\/\/ \u4f7f\u7528lodash\u7684_.get\u65b9\u6cd5<\/p>\nconst homePhone = _.get(user, 'contact.phone.home', 'No Home Phone');<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5b9e\u8df5\u4e2d\uff0c\u9009\u62e9\u9002\u5408\u7684\u8bbf\u95ee\u65b9\u5f0f\u53d6\u51b3\u4e8e\u4f60\u7684\u5177\u4f53\u9700\u6c42\u4ee5\u53ca\u4ee3\u7801\u7684\u73af\u5883\u3002\u901a\u5e38\u800c\u8a00\uff0c\u7ed3\u5408\u7ed3\u6784\u5316\u5206\u914d\u548cOptional Chaining \u662f\u4e00\u79cd\u5728\u73b0\u4ee3JavaScript\u7f16\u7a0b\u4e2d\u5e38\u7528\u4e14\u517c\u987e\u6548\u7387\u548c\u53ef\u8bfb\u6027\u7684\u4f18\u96c5\u65b9\u5f0f\u3002\u800c\u51fd\u6570\u5c01\u88c5\u5219\u4e3a\u4e0d\u540c\u7684\u5c5e\u6027\u8bbf\u95ee\u63d0\u4f9b\u4e86\u66f4\u9ad8\u7684\u590d\u7528\u6027\uff0c\u540c\u65f6\u5e93\u7684\u4f7f\u7528\u5219\u5728\u4f60\u9700\u8981\u5bf9\u73b0\u6709\u4ee3\u7801\u8fdb\u884c\u5927\u89c4\u6a21\u64cd\u4f5c\u65f6\u66f4\u52a0\u65b9\u4fbf\u3002<\/p>\n<\/p>\n
\u76f8\u5173\u95ee\u7b54FAQs\uff1a<\/strong><\/h2>\n\u5982\u4f55\u5728JavaScript\u4e2d\u4f18\u96c5\u5730\u8bbf\u95ee\u591a\u5c42\u7ea7\u5bf9\u8c61\u5c5e\u6027\uff1f<\/strong><\/p>\n\n- \n
1. \u4f7f\u7528\u70b9\u64cd\u4f5c\u7b26\u6216\u65b9\u62ec\u53f7\u64cd\u4f5c\u7b26\u8bbf\u95ee\uff1a<\/strong> JavaScript\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528\u70b9\u64cd\u4f5c\u7b26\uff08.\uff09\u6216\u65b9\u62ec\u53f7\u64cd\u4f5c\u7b26\uff08[]\uff09\u6765\u8bbf\u95ee\u591a\u5c42\u7ea7\u7684\u5bf9\u8c61\u5c5e\u6027\u3002\u4f7f\u7528\u70b9\u64cd\u4f5c\u7b26\u7684\u65b9\u5f0f\u66f4\u7b80\u6d01\u76f4\u89c2\uff0c\u4f46\u662f\u5f53\u5c5e\u6027\u540d\u5305\u542b\u7279\u6b8a\u5b57\u7b26\u6216\u8005\u662f\u53d8\u91cf\u65f6\uff0c\u9700\u8981\u4f7f\u7528\u65b9\u62ec\u53f7\u64cd\u4f5c\u7b26\u6765\u8fdb\u884c\u8bbf\u95ee\u3002<\/p>\n<\/li>\n- \n
2. \u4f7f\u7528\u53ef\u9009\u94fe\u64cd\u4f5c\u7b26\uff08?.\uff09\uff1a<\/strong> \u5982\u679c\u5728\u591a\u5c42\u7ea7\u7684\u5bf9\u8c61\u5c5e\u6027\u8bbf\u95ee\u8fc7\u7a0b\u4e2d\u67d0\u4e2a\u5c5e\u6027\u4e3aundefined\u6216null\uff0c\u4f7f\u7528\u4f20\u7edf\u65b9\u5f0f\u4f1a\u5bfc\u81f4\u7a0b\u5e8f\u51fa\u9519\u3002\u4e3a\u4e86\u907f\u514d\u8fd9\u79cd\u60c5\u51b5\uff0c\u53ef\u4ee5\u4f7f\u7528\u53ef\u9009\u94fe\u64cd\u4f5c\u7b26\uff08?.\uff09\uff0c\u5b83\u4f1a\u5728\u5c5e\u6027\u4e0d\u5b58\u5728\u65f6\u8fd4\u56deundefined\uff0c\u800c\u4e0d\u662f\u629b\u51fa\u9519\u8bef\u3002<\/p>\n<\/li>\n- \n
3. \u4f7f\u7528\u89e3\u6784\u8d4b\u503c\uff1a<\/strong> \u5728\u8bbf\u95ee\u591a\u5c42\u7ea7\u7684\u5bf9\u8c61\u5c5e\u6027\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u89e3\u6784\u8d4b\u503c\u8bed\u6cd5\u6765\u63d0\u53d6\u6240\u9700\u7684\u5c5e\u6027\u503c\u3002\u89e3\u6784\u8d4b\u503c\u80fd\u591f\u5feb\u901f\u3001\u7b80\u6d01\u5730\u4ece\u5bf9\u8c61\u4e2d\u63d0\u53d6\u591a\u4e2a\u5c5e\u6027\uff0c\u5e76\u5c06\u5b83\u4eec\u8d4b\u503c\u7ed9\u72ec\u7acb\u7684\u53d8\u91cf\u3002<\/p>\n<\/li>\n- \n
4. \u4f7f\u7528Lodash\u5e93\u7684get\u65b9\u6cd5\uff1a<\/strong> Lodash\u662f\u4e00\u4e2a\u5e38\u7528\u7684JavaScript\u5de5\u5177\u5e93\uff0c\u5176\u4e2d\u63d0\u4f9b\u4e86\u8bb8\u591a\u5b9e\u7528\u7684\u51fd\u6570\u3002\u5176\u4e2d\uff0cget\u65b9\u6cd5\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u4f18\u96c5\u5730\u8bbf\u95ee\u591a\u5c42\u7ea7\u5bf9\u8c61\u5c5e\u6027\u3002\u4f7f\u7528get\u65b9\u6cd5\uff0c\u53ea\u9700\u4f20\u9012\u5bf9\u8c61\u548c\u5c5e\u6027\u8def\u5f84\u5373\u53ef\uff0c\u5b83\u4f1a\u5728\u5c5e\u6027\u4e0d\u5b58\u5728\u65f6\u8fd4\u56deundefined\uff0c\u800c\u4e0d\u4f1a\u5bfc\u81f4\u7a0b\u5e8f\u51fa\u9519\u3002<\/p>\n<\/li>\n- \n
5. \u4f7f\u7528Proxy\u4ee3\u7406\u5bf9\u8c61\uff1a<\/strong> Proxy\u662fJavaScript\u4e2d\u7684\u4e00\u4e2a\u529f\u80fd\u5f3a\u5927\u7684\u7279\u6027\uff0c\u53ef\u4ee5\u7528\u4e8e\u62e6\u622a\u5e76\u81ea\u5b9a\u4e49\u5bf9\u5bf9\u8c61\u7684\u64cd\u4f5c\u3002\u901a\u8fc7\u4f7f\u7528Proxy\u4ee3\u7406\u5bf9\u8c61\uff0c\u6211\u4eec\u53ef\u4ee5\u5b9a\u4e49\u4e00\u4e2a\u5904\u7406\u5668\u6765\u62e6\u622a\u5bf9\u8c61\u5c5e\u6027\u7684\u8bbf\u95ee\uff0c\u4ece\u800c\u5b9e\u73b0\u4f18\u96c5\u5730\u8bbf\u95ee\u591a\u5c42\u7ea7\u5bf9\u8c61\u5c5e\u6027\u7684\u65b9\u5f0f\u3002<\/p>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"JavaScript\u4e2d\u4f7f\u7528\u591a\u5c42\u7ea7\u5bf9\u8c61\u5c5e\u6027\u7684\u6bd4\u8f83\u4f18\u96c5\u7684\u65b9\u5f0f\u5305\u62ec\u4f7f\u7528\u70b9\u7b26\u53f7\u548c\u65b9\u62ec\u53f7\u7ed3\u5408\u8bbf\u95ee\u3001\u7ed3\u6784\u5316\u5206\u914d\uff08Destr […]","protected":false},"author":3,"featured_media":165785,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[37],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/165781"}],"collection":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/comments?post=165781"}],"version-history":[{"count":0,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/165781\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media\/165785"}],"wp:attachment":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media?parent=165781"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/categories?post=165781"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/tags?post=165781"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"JavaScript\u4e2d\u4f7f\u7528\u591a\u5c42\u7ea7\u7684\u5bf9\u8c61\u5c5e\u6027\u6709\u4ec0\u4e48\u6bd4\u8f83\u4f18\u96c5\u7684\u65b9\u5f0f\"](\"https:\/\/cdn-kb.worktile.com\/kb\/wp-content\/uploads\/2024\/04\/26232837\/a7423253-0666-4b6c-ae22-b8a2a457217f.webp\")
<\/p>\n