{"id":900,"date":"2022-03-10T21:09:58","date_gmt":"2022-03-10T13:09:58","guid":{"rendered":"http:\/\/www.henrycome.com\/wordpress\/?p=900"},"modified":"2022-03-10T21:09:58","modified_gmt":"2022-03-10T13:09:58","slug":"20220310210913","status":"publish","type":"post","link":"http:\/\/www.henrycome.com\/wordpress\/202203102109\/900","title":{"rendered":"P18-\u6d41\u7a0b\u63a7\u5236-\u8bed\u53e5\u5757\uff08\u8ba8\u8bba\uff09.js"},"content":{"rendered":"<pre><code class=\"language-javascript\">\/*\u63a7\u5236\u8bed\u53e5*\/\n\/\/\u4e0d\u540c\u6761\u4ef6\u4e0d\u540c\u4ee3\u7801\uff0c\u6216\u8005\u91cd\u590d\u6267\u884c\u4e00\u4e32\u4ee3\u7801\n\n\/\/\u5148\u770b\u8bed\u53e5\u5757\uff0c\u662f\u4ee3\u7801\u7684\u96c6\u5408\uff0c\u7528{}\u5708\u8d77\u6765\u3002\u5f62\u6210\u72ec\u7acb\u7684\u8fd0\u884c\u73af\u5883\u3002\u53eb\u505a\u4f5c\u7528\u57df(\u540e\u9762\u518d\u8bf4)\n\n{\n\/\/  \u7531\u8bfe\u5802\u4f8b\u5b50\u5f15\u53d1\u7684\u5c0f\u95ee\u9898\n\/\/  var name =  &#039;\u5cf0\u534e&#039;;\n\/\/  var name ;\/\/\u91cd\u65b0\u58f0\u660e\u4e0d\u8d4b\u503c\uff0c\u4e0d\u4f1a\u66ff\u6362hello\u503c\u4e3aundefined\n\/\/  console.log(name)\/\/\u5cf0\u534e\n\n\/\/  var hello = &#039;\u5f20\u6052&#039;;\n\/\/  var hello;\/\/\u91cd\u65b0\u58f0\u660e\u4e0d\u8d4b\u503c\uff0c\u4e0d\u4f1a\u66ff\u6362hello\u503c\u4e3aundefined\n\/\/  console.log(hello);\/\/\u5f20\u6052\uff0c\n}\n\n{\n    \/\/vh\uff1a\u4e4b\u524d\u8bf4name\u6709\u95ee\u9898\uff0c\u662fhtml\u4fdd\u7559\u5b57\uff0c\n    \/\/\u8fd9\u91cc\u8fd8\u6709\u5f71\u54cd\uff0c\u5220\u9664name\u76f8\u5173\u8d4b\u503c\u8bed\u53e5\uff0c\u5373\u4f7f\u5237\u65b0\u9875\u9762\uff0cname\u8fd8\u662f&#039;\u5cf0\u534e&#039;\n\n    \/\/var name =  &#039;\u5cf0\u534e&#039;;\n    let name =  &#039;\u5cf0\u534e&#039;;\n    console.log(name)\/\/\u5cf0\u534e\n\n    \/\/\u4f46\u662f\u5047\u5982\uff0c\u4e0a\u9762\u8d4b\u503c\u8bed\u53e5var name =  &#039;\u5cf0\u534e&#039;\u5220\u6389\uff0c\u4fdd\u5b58\uff0c\u518d\u8fd0\u884c\u53ea\u6709\u4e0b\u9762\u8fd9\u53e5\uff1a\n    console.log(name)\/\/\u5cf0\u534e\uff0c\n    \/*\n    1.\u5982\u679c\u662fhello\u7684\u8bdd\uff0c\u80af\u5b9a\u5c31\u662fundefined\uff0c\u4f46\u662fname\u5c45\u7136\u4fdd\u7559\u7740\n    2.\u9664\u975e\u5173\u95ed\u7f51\u9875\u3002\u91cd\u65b0\u6253\u5f00\u7f51\u9875\u3002\n    3.\u6240\u4ee5\uff0c\u5c3d\u91cf\u522b\u7528\u8fd9\u4e9b\u5173\u952e\u5b57\u3002\n    4.\u770b\u4e0b\u9762\u7684\u666e\u901a\u53d8\u91cf\u540d\u5b57\u7684\u4f8b\u5b50\uff0c\u662f\u6ca1\u6709\u8fd9\u6837\u7684\u73b0\u8c61\u7684\n    5.\u5982\u679c\u662flet\u58f0\u660e\u7684\u8bdd\uff0c\u5c31\u6b63\u5e38\u4e86\uff0c\u5c31\u6ca1\u6709\u4e0a\u9762\u7684\u5237\u65b0\u8fd8\u80fd\u4fdd\u7559\u53d8\u91cf\u503c\u7684\u60c5\u51b5\u3002\u5220\u9664let name = &#039;\u5cf0\u534e&#039;\uff0c\u8fd9\u91cc\u5c31\u4f1a\u663e\u793a\u7a7a\u5360\u4e00\u884c\u3002\u8fd9\u4e5f\u662fname\u7684\u7279\u8272\uff0c\u6ca1\u6709\u8bed\u6cd5\u9519\u8bef\uff0c\u4f46\u662f\u4f1a\u7a7a\u5360\u4e00\u884c\n    6.\u666e\u901a\u53d8\u91cfhello\u5982\u679c\u662f\u6ca1\u6709\u58f0\u660e\uff0c\u5c31\u4f7f\u7528\uff0c\u4f1a\u63d0\u793a\u8bed\u6cd5\u9519\u8bef\uff0chello is not defined\n    *\/\n\n   \/\/var hello;\n   let hello;\n   console.log(hello);\/\/undefined\uff0c\u4e0b\u9762\u6709\u8d4b\u503c\u8bed\u53e5\uff0c\u4f46\u662f\u5237\u65b0\u540e\uff0c\u5230\u8fd9\u884c\u8fd8\u662fundefined\n   hello = 1\n\n}\nconsole.log(name);\/\/\u5cf0\u534e\uff0cvar\u5728{}\u5b9a\u4e49\u7684\u4e0a\u5c42\u53ef\u4ee5\u8bbf\u95ee;let\u5728{}\u5b9a\u4e49\u4e0a\u5c42\u4e0d\u53ef\u8bbf\u95ee\uff0c\u8fd9\u91cc\u662fname\u6240\u4ee5\u662f\u6ca1\u6709\u663e\u793a\uff0c\u4f46\u5360\u7528\u4e00\u884c\nconsole.log(hello);\/\/1\uff0cvar\u5728{}\u5b9a\u4e49\u7684\u4e0a\u5c42\u53ef\u4ee5\u8bbf\u95ee;let\u5728{}\u91cc\u9762\u5b9a\u4e49\uff0c\u8fd9\u91cchello is not defined.\u8bed\u6cd5\u62a5\u9519\u4e86\u3002\n\n\/*\nvar \u58f0\u660e\u662f\u5168\u5c40\u53d8\u91cf\uff0c\u4e0d\u53d7\u4f5c\u7528\u57df\u7684\u5f71\u54cd\n\u4e0d\u7528var\uff0c\u76f4\u63a5\u58f0\u660e\uff0c\u662f\u5168\u5c40\u53d8\u91cf\u3002\nlet\u548cconst\u58f0\u660e\uff0c\u662f\u5c40\u90e8\u53d8\u91cf\uff0c\u5728\u4f5c\u7528\u57df\u5185\u4f7f\u7528\n*\/<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\/*\u63a7\u5236\u8bed\u53e5*\/ 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