javascript
\nJS\u53d8\u91cf\u662f\u677e\u6563\u578b\u7684(\u4e0d\u5f3a\u5236\u7c7b\u578b)\u672c\u8d28,\u51b3\u5b9a\u4e86\u5b83\u53ea\u662f\u5728\u7279\u5b9a\u65f6\u95f4\u7528\u4e8e\u4fdd\u5b58\u7279\u5b9a\u503c\u7684\u4e00\u4e2a\u540d\u5b57\u800c\u5df2;\u7531\u4e8e\u4e0d\u5b58\u5728\u5b9a\u4e49\u67d0\u4e2a\u53d8\u91cf\u5fc5\u987b\u8981\u4fdd\u5b58\u4f55\u79cd\u6570\u636e\u7c7b\u578b\u503c\u7684\u89c4\u5219,\u53d8\u91cf\u7684\u503c\u53ca\u5176\u6570\u636e\u7c7b\u578b\u53ef\u4ee5\u5728\u811a\u672c\u7684\u751f\u547d\u5468\u671f\u5185\u6539\u53d8;
\n\u4e00 \u53d8\u91cf\u53ca\u4f5c\u7528\u57df1.\u57fa\u672c\u7c7b\u578b\u548c\u5f15\u7528\u7c7b\u578b
\n\/\/ JS\u53d8\u91cf\u5305\u542b\u4e24\u79cd\u4e0d\u540c\u7684\u6570\u636e\u7c7b\u578b\u7684\u503c:\u57fa\u672c\u7c7b\u578b\u503c\u548c\u5f15\u7528\u7c7b\u578b\u503c;
\n\/\/ 1.\u57fa\u672c\u7c7b\u578b\u503c:\u4fdd\u5b58\u5728\u6808\u5185\u5b58\u4e2d\u7684\u7b80\u5355\u6570\u636e\u6bb5;\u5373\u8fd9\u79cd\u503c\u5b8c\u5168\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\u7684\u4e00\u4e2a\u4f4d\u7f6e;\/\/ \u57fa\u672c\u7c7b\u578b\u503c\u5305\u542b:Undefined|Null|Boolean|Number|String;\/\/ \u8fd9\u4e9b\u7c7b\u578b\u5728\u5185\u5b58\u4e2d\u5360\u6709\u56fa\u5b9a\u5927\u5c0f\u7684\u7a7a\u95f4;\u5b83\u4eec\u7684\u503c\u4fdd\u5b58\u5728\u6808\u7a7a\u95f4,\u6211\u4eec\u6309\u503c\u6765\u8bbf\u95ee;
\n\/\/ 2.\u5f15\u7528\u7c7b\u578b\u503c:\u4fdd\u5b58\u5728\u5806\u5185\u5b58\u4e2d\u7684\u5bf9\u8c61(\u53ef\u80fd\u7531\u591a\u4e2a\u503c\u6784\u6210),\u5373\u53d8\u91cf\u4e2d\u4fdd\u5b58\u7684\u5b9e\u9645\u4e0a\u53ea\u662f\u4e00\u4e2a\u6307\u9488,\u8fd9\u4e2a\u6307\u9488\u6307\u5411\u5185\u5b58\u4e2d\u7684\u53e6\u4e00\u4e2a\u4f4d\u7f6e,\u8be5\u4f4d\u7f6e\u4fdd\u5b58\u5bf9\u8c61;\/\/ \u5f15\u7528\u7c7b\u578b\u7684\u503c\u7684\u5927\u5c0f\u4e0d\u56fa\u5b9a,\u56e0\u6b64\u4e0d\u80fd\u4fdd\u5b58\u5728\u6808\u5185\u5b58,\u5fc5\u987b\u4fdd\u5b58\u5728\u5806\u5185\u5b58\u4e2d;\u4f46\u53ef\u4ee5\u5c06\u5f15\u7528\u7c7b\u578b\u7684\u503c\u7684\u5185\u5b58\u5730\u5740\u4fdd\u5b58\u5728\u6808\u5185\u5b58\u4e2d;\/\/ \u5f53\u67e5\u8be2\u5f15\u7528\u7c7b\u578b\u7684\u53d8\u91cf\u65f6,\u5148\u4ece\u6808\u5185\u5b58\u4e2d\u8bfb\u53d6\u5185\u5b58\u5730\u5740,\u7136\u540e\u901a\u8fc7\u5730\u5740\u627e\u5230\u5806\u5185\u5b58\u4e2d\u7684\u503c;=>\u6309\u5f15\u7528\u8bbf\u95ee;
\n2.\u52a8\u6001\u5c5e\u6027
\n\/\/ \u5b9a\u4e49\u57fa\u672c\u7c7b\u578b\u503c\u548c\u5f15\u7528\u7c7b\u578b\u503c\u7684\u65b9\u5f0f\u76f8\u4f3c:\u521b\u5efa\u4e00\u4e2a\u53d8\u91cf\u5e76\u4e3a\u8be5\u53d8\u91cf\u8d4b\u503c;
\n\/\/ \u4f46\u5f53\u8fd9\u4e2a\u503c\u4fdd\u5b58\u5230\u53d8\u91cf\u4e2d\u4ee5\u540e,\u5bf9\u4e0d\u540c\u7c7b\u578b\u503c\u53ef\u4ee5\u6267\u884c\u7684\u64cd\u4f5c\u5219\u4e0d\u4e00\u6837;
\nvar box = new Object();\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u521b\u5efa\u5f15\u7528\u7c7b\u578b;
\nbox.name = “lee”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u65b0\u589e\u4e00\u4e2a\u5c5e\u6027;
\nconsole.log(box.name);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ =>lee;<\/p>\n
var box = “lee”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u521b\u5efa\u57fa\u672c\u7c7b\u578b
\nbox.age = 15;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ \u7ed9\u57fa\u672c\u7c7b\u578b\u6dfb\u52a0\u5c5e\u6027;\u00a0\u00a0console.log(box.age);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\/\/ =>undefined;
\n3.\u590d\u5236\u53d8\u91cf\u503c
\n\/\/ \u5728\u53d8\u91cf\u590d\u5236\u65b9\u9762,\u57fa\u672c\u7c7b\u578b\u548c\u5f15\u7528\u7c7b\u578b\u4e5f\u6709\u6240\u4e0d\u540c;
\n\/\/ \u57fa\u672c\u7c7b\u578b\u8d4b\u503c\u7684\u662f\u503c\u672c\u8eab;
\nvar box = “lee”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u5728\u6808\u5185\u5b58\u4e2d\u751f\u6210\u4e00\u4e2abox”lee”;
\nvar box2 = box;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\/\/ \u5728\u6808\u5185\u5b58\u4e2d\u518d\u751f\u6210\u4e00\u4e2abox2″lee”;
\n\/\/ box\u548cbox2\u5b8c\u5168\u72ec\u7acb;\u4e24\u4e2a\u53d8\u91cf\u5206\u522b\u64cd\u4f5c\u65f6\u4e92\u4e0d\u5f71\u54cd;<\/p>\n
\/\/ \u5f15\u7528\u7c7b\u578b\u8d4b\u503c\u7684\u662f\u5730\u5740;
\nvar box = new Object();\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ \u521b\u5efa\u4e00\u4e2a\u5f15\u7528\u7c7b\u578b;box\u5728\u6808\u5185\u5b58\u4e2d;\u800cObject\u5728\u5806\u5185\u5b58\u4e2d;
\nbox.name = “lee”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ \u65b0\u589e\u4e00\u4e2a\u5c5e\u6027;
\nvar box2 = box;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u628a\u5f15\u7528\u5730\u5740\u8d4b\u503c\u7ed9box2;box2\u5728\u6808\u5185\u5b58\u4e2d;
\n\/\/ box2=box,\u56e0\u4e3a\u5b83\u4eec\u6307\u5411\u7684\u662f\u540c\u4e00\u4e2a\u5bf9\u8c61;\u00a0\u00a0\/\/ \u5982\u679c\u8fd9\u4e2a\u5bf9\u8c61\u4e2d\u7684name\u5c5e\u6027\u88ab\u4fee\u6539\u4e86,box.name\u548cbox2.name\u8f93\u51fa\u7684\u503c\u90fd\u4f1a\u88ab\u4fee\u6539\u6389;
\n4.\u4f20\u9012\u53c2\u6570
\n\/\/ JS\u4e2d\u6240\u6709\u51fd\u6570\u7684\u53c2\u6570\u90fd\u662f\u6309\u503c\u4f20\u9012\u7684,\u5373\u53c2\u6570\u4e0d\u4f1a\u6309\u5f15\u7528\u4f20\u9012;
\nfunction box(num){\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ \u6309\u503c\u4f20\u9012,\u4f20\u9012\u7684\u53c2\u6570\u662f\u57fa\u672c\u7c7b\u578b;
\nnum +=10;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\/\/ \u8fd9\u91cc\u7684num\u662f\u5c40\u90e8\u53d8\u91cf,\u5168\u5c40\u65e0\u6548;
\nreturn num;
\n}
\nvar num = 50;
\nvar result = box(num);
\nconsole.log(result);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ 60;
\nconsole.log(num);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ 50;<\/p>\n
function box(num){
\nreturn num;
\n}
\nconsole.log(num);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ num is not defined;<\/p>\n
function box(obj){
\nobj.name = “lee”;
\nvar obj = new Object();\u00a0 \u00a0\u00a0 \u00a0 \/\/ \u51fd\u6570\u5185\u90e8\u53c8\u521b\u5efa\u4e86\u4e00\u4e2a\u5bf9\u8c61,\u5b83\u662f\u5c40\u90e8\u53d8\u91cf;\u4f46\u5728\u51fd\u6570\u7ed3\u675f\u65f6\u88ab\u9500\u6bc1\u4e86;
\nobj.name = “Mr”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u5e76\u6ca1\u6709\u66ff\u6362\u6389\u539f\u6765\u7684obj;
\n}
\nvar p = new Object();
\nbox(p);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u53d8\u91cfp\u88ab\u4f20\u9012\u5230box()\u51fd\u6570\u4e2d\u4e4b\u540e\u5c31\u88ab\u590d\u5236\u7ed9\u4e86obj;\u5728\u51fd\u6570\u5185\u90e8,obj\u548cp\u8bbf\u95ee\u7684\u662f\u540c\u4e00\u4e2a\u5bf9\u8c61;
\nconsole.log(p.name);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ =>lee;
\n\/\/ JS\u51fd\u6570\u7684\u53c2\u6570\u90fd\u5c06\u662f\u5c40\u90e8\u53d8\u91cf;\u4e5f\u5c31\u662f\u8bf4,\u6ca1\u6709\u6309\u5f15\u7528\u4f20\u9012;
\n5.\u68c0\u6d4b\u7c7b\u578b
\n\/\/ \u8981\u68c0\u6d4b\u4e00\u4e2a\u53d8\u91cf\u7684\u7c7b\u578b,\u901a\u8fc7typeof\u8fd0\u7b97\u7b26\u7c7b\u5224\u65ad;
\n\/\/ \u591a\u7528\u6765\u68c0\u6d4b\u57fa\u672c\u7c7b\u578b;
\nvar box = “lee”;
\nconsole.log(typeof box);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ =>string;<\/p>\n
\/\/ \u8981\u68c0\u6d4b\u53d8\u91cf\u662f\u4ec0\u4e48\u7c7b\u578b\u7684\u5bf9\u8c61,\u901a\u8fc7instanceof\u8fd0\u7b97\u7b26\u6765\u67e5\u770b;
\nvar box = [1,2,3];
\nconsole.log(box instanceof Array);\u00a0 \u00a0\u00a0\u00a0\/\/ =>true;
\nvar box2 = {};
\nconsole.log(box2 instanceof Object);
\nvar box3 = \/g\/;
\nconsole.lgo(box3 instanceof RegExp);
\nvar box4 = new String(“lee”);
\nconsole.log(box4 instanceof String);\u00a0 \u00a0\/\/ =>true;\u662f\u5426\u662f\u5b57\u7b26\u4e32\u5bf9\u8c61;<\/p>\n
var box5 = “string”;
\nconsole.log(box5 instanceof String);\u00a0 \u00a0\/\/ =>false;\u00a0\u00a0\/\/ \u5f53\u4f7f\u7528instanceof\u68c0\u67e5\u57fa\u672c\u7c7b\u578b\u7684\u503c\u65f6,\u5b83\u4f1a\u8fd4\u56defalse;
\n6.\u6267\u884c\u73af\u5883\u53ca\u4f5c\u7528\u57df
\n\/\/ \u6267\u884c\u73af\u5883:\u5b9a\u4e49\u4e86\u53d8\u91cf\u6216\u51fd\u6570\u6709\u6743\u8bbf\u95ee\u7684\u5176\u4ed6\u6570\u636e,\u51b3\u5b9a\u4e86\u5b83\u4eec\u5404\u81ea\u7684\u884c\u4e3a;
\n\/\/ \u5728Web\u6d4f\u89c8\u5668\u4e2d,\u5168\u5c40\u6267\u884c\u73af\u5883=window\u5bf9\u8c61;
\n\/\/ \u56e0\u6b64\u6240\u6709\u7684\u5168\u5c40\u53d8\u91cf\u548c\u51fd\u6570\u90fd\u662f\u4f5c\u4e3awindow\u5bf9\u8c61\u7684\u5c5e\u6027\u548c\u65b9\u6cd5\u521b\u5efa\u7684;
\nvar box = “blue”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ \u58f0\u660e\u4e00\u4e2a\u5168\u5c40\u53d8\u91cf;
\nfunction setBox(){
\nconsole.log(box);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u5168\u5c40\u53d8\u91cf\u53ef\u4ee5\u5728\u51fd\u6570\u91cc\u8bbf\u95ee;
\n}
\nsetBox();\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u6267\u884c\u51fd\u6570;
\n\/\/ \u5168\u5c40\u7684\u53d8\u91cf=window\u5bf9\u8c61\u7684\u5c5e\u6027;
\n\/\/ \u5168\u5c40\u7684\u51fd\u6570=window\u5bf9\u8c61\u7684\u65b9\u6cd5;<\/p>\n
\/\/ PS:\u5f53\u6267\u884c\u73af\u5883\u4e2d\u7684\u6240\u6709\u4ee3\u7801\u6267\u884c\u5b8c\u6bd5\u540e,\u8be5\u73af\u5883\u88ab\u9500\u6bc1,\u4fdd\u5b58\u5728\u5176\u4e2d\u7684\u6240\u6709\u53d8\u91cf\u548c\u51fd\u6570\u5b9a\u4e49\u4e5f\u968f\u4e4b\u9500\u6bc1;
\n\/\/ \u5982\u679c\u662f\u5728\u5168\u5c40\u73af\u5883\u4e0b,\u9700\u8981\u7a0b\u5e8f\u6267\u884c\u5b8c\u6bd5,\u6216\u8005\u7f51\u9875\u88ab\u5173\u95ed\u624d\u4f1a\u9500\u6bc1;<\/p>\n
\/\/ PS:\u6bcf\u4e2a\u6267\u884c\u73af\u5883\u90fd\u6709\u4e00\u4e2a\u4e0e\u4e4b\u5173\u8054\u7684\u53d8\u91cf\u5bf9\u8c61,\u5c31\u597d\u6bd4\u5168\u5c40\u7684window\u53ef\u4ee5\u8c03\u7528\u5168\u5c40\u53d8\u91cf\u548c\u5168\u5c40\u65b9\u6cd5\u4e00\u6837;
\n\/\/ \u5c40\u90e8\u7684\u73af\u5883\u4e5f\u6709\u4e00\u4e2a\u7c7b\u4f3cwindow\u7684\u53d8\u91cf\u5bf9\u8c61,\u73af\u5883\u4e2d\u5b9a\u4e49\u7684\u6240\u6709\u53d8\u91cf\u548c\u51fd\u6570\u90fd\u4fdd\u5b58\u5728\u8fd9\u4e2a\u5bf9\u8c61\u4e2d;
\n\/\/ (\u6211\u4eec\u65e0\u6cd5\u8bbf\u95ee\u8fd9\u4e2a\u53d8\u91cf\u5bf9\u8c61,\u4f46\u89e3\u6790\u5668\u4f1a\u5904\u7406\u6570\u636e\u65f6\u540e\u53f0\u4f7f\u7528\u5b83);
\nvar box = “blue”;
\nfunction setBox(){
\nvar box = “red”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u8fd9\u91cc\u662f\u5c40\u90e8\u53d8\u91cf,\u5728\u5f53\u524d\u51fd\u6570\u4f53\u5185\u7684\u503c\u662f”red”;\u51fa\u4e86\u51fd\u6570\u4f53\u5c31\u4e0d\u88ab\u8ba4\u77e5;
\nconsole.log(box);
\n}
\nsetBox();
\nconsole.log(box);<\/p>\n
\/\/ \u901a\u8fc7\u4f20\u53c2\u53ef\u4ee5\u66ff\u6362\u51fd\u6570\u4f53\u5185\u7684\u5c40\u90e8\u53d8\u91cf,\u4f46\u4f5c\u7528\u57df\u4ec5\u9650\u5728\u51fd\u6570\u4f53\u5185\u8fd9\u4e2a\u5c40\u90e8\u73af\u5883;
\nvar box = “blue”;
\nfunction setBox(box){\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u901a\u8fc7\u4f20\u53c2,\u5c06\u5c40\u90e8\u53d8\u91cf\u66ff\u6362\u6210\u4e86\u5168\u5c40\u53d8\u91cf;
\nalert(box);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u6b64\u65f6box\u7684\u503c\u662f\u5916\u90e8\u8c03\u7528\u65f6\u4f20\u5165\u7684\u53c2\u6570;=>red;
\n}
\nsetBox(“red”);
\nalert(box);<\/p>\n
\/\/ \u5982\u679c\u51fd\u6570\u4f53\u5185\u8fd8\u5305\u542b\u7740\u51fd\u6570,\u53ea\u6709\u8fd9\u4e2a\u5185\u51fd\u6570\u624d\u53ef\u4ee5\u8bbf\u95ee\u5916\u4e00\u5c42\u7684\u51fd\u6570\u7684\u53d8\u91cf;
\n\/\/ \u5185\u90e8\u73af\u5883\u53ef\u4ee5\u901a\u8fc7\u4f5c\u7528\u57df\u94fe\u8bbf\u95ee\u6240\u6709\u7684\u5916\u90e8\u73af\u5883,\u4f46\u5916\u90e8\u73af\u5883\u4e0d\u80fd\u8bbf\u95ee\u5185\u90e8\u73af\u5883\u4e2d\u7684\u4efb\u4f55\u53d8\u91cf\u548c\u51fd\u6570;
\nvar box = “blue”;
\nfunction setBox(){
\nfunction setColor(){
\nvar b = “orange”;
\nalert(box);
\nalert(b);
\n}
\nsetColor();\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ setColor()\u7684\u6267\u884c\u73af\u5883\u5728setBox()\u5185;
\n}
\nsetBox();
\n\/\/ PS:\u6bcf\u4e2a\u51fd\u6570\u88ab\u8c03\u7528\u65f6\u90fd\u4f1a\u521b\u5efa\u81ea\u5df1\u7684\u6267\u884c\u73af\u5883;\u5f53\u6267\u884c\u5230\u8fd9\u4e2a\u51fd\u6570\u65f6,\u51fd\u6570\u7684\u73af\u5883\u5c31\u4f1a\u88ab\u63a8\u5230\u73af\u5883\u6808\u4e2d\u53bb\u6267\u884c,\u800c\u6267\u884c\u540e\u53c8\u5728\u73af\u5883\u6808\u4e2d\u5f39\u51fa(\u9000\u51fa),\u628a\u63a7\u5236\u6743\u4ea4\u7ed9\u4e0a\u4e00\u7ea7\u7684\u6267\u884c\u73af\u5883;
\n\/\/ PS:\u5f53\u4ee3\u7801\u5728\u4e00\u4e2a\u73af\u5883\u4e2d\u6267\u884c\u65f6,\u5c31\u4f1a\u5f62\u6210\u4e00\u79cd\u53eb\u505a\u4f5c\u7528\u57df\u94fe\u7684\u4e1c\u897f;\u5b83\u7684\u7528\u9014\u662f\u4fdd\u8bc1\u5bf9\u6267\u884c\u73af\u5883\u4e2d\u6709\u8bbf\u95ee\u6743\u9650\u7684\u53d8\u91cf\u548c\u51fd\u6570\u8fdb\u884c\u6709\u5e8f\u8bbf\u95ee;\u4f5c\u7528\u57df\u94fe\u7684\u524d\u7aef,\u5c31\u662f\u6267\u884c\u73af\u5883\u7684\u53d8\u91cf\u5bf9\u8c61;
\n7.\u5ef6\u957f\u4f5c\u7528\u57df\u94fe
\n\/\/ \u6709\u4e9b\u8bed\u53e5\u53ef\u4ee5\u5728\u4f5c\u7528\u57df\u94fe\u7684\u524d\u7aef\u4e34\u65f6\u589e\u52a0\u4e00\u4e2a\u53d8\u91cf\u5bf9\u8c61,\u8be5\u53d8\u91cf\u5bf9\u8c61\u4f1a\u5728\u4ee3\u7801\u6267\u884c\u540e\u88ab\u79fb\u9664;
\n\/\/ with\u8bed\u53e5\u548ctry-catch\u8bed\u53e5;\u8fd9\u4e24\u4e2a\u8bed\u53e5\u90fd\u4f1a\u5728\u4f5c\u7528\u57df\u94fe\u7684\u524d\u7aef\u6dfb\u52a0\u4e00\u4e2a\u53d8\u91cf\u5bf9\u8c61;
\n\/\/ with\u8bed\u53e5:\u4f1a\u5c06\u6307\u5b9a\u7684\u5bf9\u8c61\u6dfb\u52a0\u5230\u4f5c\u7528\u57df\u94fe\u4e2d;
\n\/\/ catch\u8bed\u53e5:\u4f1a\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u53d8\u91cf\u5bf9\u8c61,\u5176\u4e2d\u5305\u542b\u7684\u662f\u88ab\u629b\u51fa\u7684\u9519\u8bef\u5bf9\u8c61\u7684\u58f0\u660e;
\nfunction buildUrl(){
\nvar qs = “?debug=true”;
\nwith(location){\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\/\/ with\u8bed\u53e5\u63a5\u6536\u7684\u662flocation\u5bf9\u8c61,\u56e0\u6b64\u53d8\u91cf\u5bf9\u8c61\u4e2d\u5c31\u5305\u542b\u4e86location\u5bf9\u8c61\u7684\u6240\u6709\u5c5e\u6027\u548c\u65b9\u6cd5;
\nvar url = href+qs;\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u800c\u8fd9\u4e2a\u53d8\u91cf\u5bf9\u8c61\u88ab\u6dfb\u52a0\u5230\u4e86\u4f5c\u7528\u57df\u94fe\u7684\u524d\u7aef;
\n};
\nreturn url;\u00a0\u00a0}
\n8.\u6ca1\u6709\u5757\u7ea7\u4f5c\u7528\u57df
\n\/\/ \u5757\u7ea7\u4f5c\u7528\u57df:\u8868\u793a\u8bf8\u5982if\u8bed\u53e5\u7b49\u6709\u82b1\u62ec\u53f7\u5c01\u95ed\u7684\u4ee3\u7801\u5757,\u6240\u4ee5,\u652f\u6301\u6761\u4ef6\u5224\u65ad\u6765\u5b9a\u4e49\u53d8\u91cf;
\nif(true){\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ if\u8bed\u53e5\u4ee3\u7801\u5757\u6ca1\u6709\u5c40\u90e8\u4f5c\u7528\u57df;
\nvar box = “lee”;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u53d8\u91cf\u58f0\u660e\u4f1a\u5c06\u53d8\u91cf\u6dfb\u52a0\u5230\u5f53\u524d\u7684\u6267\u884c\u73af\u5883(\u5728\u8fd9\u91cc\u662f\u5168\u5c40\u73af\u5883);
\n}
\nalert(box);<\/p>\n
for(var i=0; i<10; i++){\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\/\/ \u521b\u5efa\u7684\u53d8\u91cfi\u5373\u4f7f\u5728for\u5faa\u73af\u6267\u884c\u7ed3\u675f\u540e,\u4e5f\u4f9d\u65e7\u4f1a\u5b58\u5728\u4e0e\u5faa\u73af\u5916\u90e8\u7684\u6267\u884c\u73af\u5883\u4e2d;
\nvar box = “lee”;
\n}
\nalert(i);
\nalert(box);<\/p>\n
function box(num1,num2){
\nvar sum = num1+num2;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\/\/ \u6b64\u65f6sum\u662f\u5c40\u90e8\u53d8\u91cf;\u5982\u679c\u53bb\u6389var,sum\u5c31\u662f\u5168\u5c40\u53d8\u91cf\u4e86;
\nreturn sum;
\n}
\nalert(box(10,10));
\nalert(sum);\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0 \/\/ sum is not defined;\u8bbf\u95ee\u4e0d\u5230sum;
\n\/\/ PS:\u4e0d\u5efa\u8bae\u4e0d\u4f7f\u7528var\u5c31\u521d\u59cb\u5316\u53d8\u91cf,\u56e0\u4e3a\u8fd9\u79cd\u65b9\u6cd5\u4f1a\u5bfc\u81f4\u5404\u79cd\u610f\u5916\u53d1\u751f;<\/p>\n
\/\/ \u4e00\u822c\u786e\u5b9a\u53d8\u91cf\u90fd\u662f\u901a\u8fc7\u641c\u7d22\u6765\u786e\u5b9a\u8be5\u6807\u8bc6\u7b26\u5b9e\u9645\u4ee3\u8868\u4ec0\u4e48;\u641c\u7d22\u65b9\u5f0f:\u5411\u4e0a\u9010\u7ea7\u67e5\u8be2;
\nvar box = “blue”;
\nfunction getBox(){
\nreturn box;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\/\/ \u6b64\u65f6box\u662f\u5168\u5c40\u53d8\u91cf;\u5982\u679c\u662fvar box=”red”,\u90a3\u5c31\u53d8\u6210\u5c40\u90e8\u53d8\u91cf\u4e86;
\n}
\nalert(getBox());
\n\/\/ \u8c03\u7528getBox()\u65f6\u4f1a\u5f15\u7528\u53d8\u91cfbox;
\n\/\/ \u9996\u5148,\u641c\u7d22getBox()\u7684\u53d8\u91cf\u5bf9\u8c61,\u67e5\u627e\u540d\u4e3abox\u7684\u6807\u8bc6\u7b26;
\n\/\/ \u7136\u540e,\u641c\u7d22\u7ee7\u7eed\u4e0b\u4e00\u4e2a\u53d8\u91cf\u5bf9\u8c61(\u5168\u5c40\u73af\u5883\u7684\u53d8\u91cf\u5bf9\u8c61),\u627e\u5230\u4e86box\u6807\u8bc6\u7b26;\/\/ PS:\u53d8\u91cf\u67e5\u8be2\u4e2d\uff0c\u8bbf\u95ee\u5c40\u90e8\u53d8\u91cf\u8981\u6bd4\u5168\u5c40\u53d8\u91cf\u66f4\u5feb\uff0c\u56e0\u4e3a\u4e0d\u9700\u8981\u5411\u4e0a\u641c\u7d22\u4f5c\u7528\u57df\u94fe\uff1b
\n\u4e8c \u5185\u5b58\u95ee\u9898
\n\/\/ JS\u5177\u6709\u81ea\u52a8\u5783\u573e\u6536\u96c6\u673a\u5236,\u6267\u884c\u73af\u5883\u4f1a\u8d1f\u8d23\u7ba1\u7406\u4ee3\u7801\u6267\u884c\u8fc7\u7a0b\u4e2d\u4f7f\u7528\u7684\u5185\u5b58;\u5b83\u4f1a\u81ea\u884c\u7ba1\u7406\u5185\u5b58\u5206\u914d\u53ca\u65e0\u7528\u5185\u5b58\u7684\u56de\u6536;<\/p>\n
\/\/ JS\u6700\u5e38\u7528\u7684\u5783\u573e\u6536\u96c6\u65b9\u5f0f\u5c31\u662f\u6807\u8bb0\u6e05\u9664;\u5783\u573e\u6536\u96c6\u5668\u4f1a\u5728\u8fd0\u884c\u7684\u65f6\u5019\u7ed9\u5b58\u50a8\u5728\u5185\u5b58\u4e2d\u7684\u53d8\u91cf\u52a0\u4e0a\u6807\u8bb0;
\n\/\/ \u7136\u540e,\u5b83\u4f1a\u53bb\u6389\u73af\u5883\u4e2d\u6b63\u5728\u4f7f\u7528\u7684\u53d8\u91cf\u7684\u6807\u8bb0,\u800c\u6ca1\u6709\u88ab\u53bb\u6389\u6807\u8bb0\u7684\u53d8\u91cf\u5c06\u88ab\u89c6\u4e3a\u51c6\u5907\u5220\u9664\u7684\u53d8\u91cf;
\n\/\/ \u6700\u540e,\u5783\u573e\u6536\u96c6\u5668\u5b8c\u6210\u5185\u5b58\u6e05\u7406\u5de5\u4f5c,\u9500\u6bc1\u90a3\u4e9b\u6807\u8bb0\u7684\u503c\u5e76\u56de\u6536\u4ed6\u4eec\u6240\u5360\u7528\u7684\u5185\u5b58\u7a7a\u95f4;<\/p>\n
\/\/ \u5783\u573e\u6536\u96c6\u5668\u662f\u5468\u671f\u6027\u8fd0\u884c\u7684,\u8fd9\u6837\u4f1a\u5bfc\u81f4\u6574\u4e2a\u7a0b\u5e8f\u7684\u6027\u80fd\u95ee\u9898;
\n\/\/ \u6bd4\u5982IE7\u4ee5\u524d\u7684\u7248\u672c,\u4ed6\u7684\u5783\u573e\u6536\u96c6\u5668\u662f\u6839\u636e\u5185\u5b58\u5206\u914d\u91cf\u8fd0\u884c\u7684,\u6bd4\u5982256\u4e2a\u53d8\u91cf\u5c31\u5f00\u59cb\u8fd0\u884c\u5783\u573e\u6536\u96c6\u5668,\u8fd9\u6837\u5c31\u4e0d\u5f97\u4e0d\u9891\u7e41\u5730\u8fd0\u884c,\u4ece\u800c\u964d\u4f4e\u4e86\u6027\u80fd;<\/p>\n
\/\/ \u4e00\u822c\u6765\u8bf4,\u786e\u4fdd\u5360\u7528\u6700\u5c11\u7684\u5185\u5b58\u53ef\u4ee5\u8ba9\u9875\u9762\u83b7\u5f97\u66f4\u597d\u7684\u6027\u80fd;
\n\/\/ \u6700\u4f73\u65b9\u6848:\u4e00\u65e6\u6570\u636e\u4e0d\u518d\u4f7f\u7528,\u5c06\u5176\u503c\u8bbe\u7f6e\u4e3anull\u6765\u91ca\u653e\u5f15\u7528,\u8fd9\u4e2a\u505a\u6cd5\u53eb\u505a\u89e3\u9664\u5f15\u7528;
\nvar o = {
\nname:”lee”;
\n};\u00a0\u00a0o = null;\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\u00a0 \u00a0\/\/ \u89e3\u9664\u5bf9\u8c61\u5f15\u7528,\u7b49\u5f85\u5783\u573e\u6536\u96c6\u5668\u56de\u6536;<\/p>\n
\u4e09 \u5c0f\u7ed3
\n1.\u53d8\u91cf\/\/ JS\u53d8\u91cf\u53ef\u4ee5\u4fdd\u5b58\u4e24\u79cd\u7c7b\u578b\u7684\u503c:\u57fa\u672c\u7c7b\u578b\u503c\u548c\u5f15\u7528\u7c7b\u578b\u503c;\u5b83\u4eec\u5177\u6709\u4ee5\u4e0b\u7279\u70b9:\/\/ 1.\u57fa\u672c\u7c7b\u578b\u503c\u5728\u5185\u5b58\u4e2d\u5360\u636e\u56fa\u5b9a\u5927\u5c0f\u7684\u7a7a\u95f4,\u56e0\u6b64\u88ab\u4fdd\u5b58\u5728\u6808\u5185\u5b58\u4e2d;\/\/ 2.\u4ece\u4e00\u4e2a\u53d8\u91cf\u5411\u53e6\u4e00\u4e2a\u53d8\u91cf\u590d\u5236\u57fa\u672c\u7c7b\u578b\u7684\u503c,\u4f1a\u521b\u5efa\u8fd9\u4e2a\u503c\u7684\u4e00\u4e2a\u526f\u672c;\/\/ 3.\u5f15\u7528\u7c7b\u578b\u7684\u503c\u662f\u5bf9\u8c61,\u4fdd\u5b58\u5728\u5806\u5185\u5b58\u4e2d;\/\/ 4.\u5305\u542b\u5f15\u7528\u7c7b\u578b\u503c\u7684\u53d8\u91cf\u5b9e\u9645\u4e0a\u5305\u542b\u7684\u5e76\u4e0d\u662f\u5bf9\u8c61\u672c\u8eab,\u800c\u662f\u4e00\u4e2a\u6307\u5411\u8be5\u5bf9\u8c61\u7684\u6307\u9488;\/\/ 5.\u4ece\u4e00\u4e2a\u53d8\u91cf\u5411\u53e6\u4e00\u4e2a\u53d8\u91cf\u590d\u5236\u5f15\u7528\u7c7b\u578b\u7684\u503c,\u590d\u5236\u7684\u5176\u5b9e\u662f\u6307\u9488,\u56e0\u6b64\u4e24\u4e2a\u53d8\u91cf\u6700\u7ec8\u90fd\u6307\u5411\u7528\u4e00\u4e2a\u5bf9\u8c61;\/\/ 6.\u786e\u5b9a\u4e00\u4e2a\u503c\u662f\u54ea\u79cd\u57fa\u672c\u7c7b\u578b\u53ef\u4ee5\u4f7f\u7528typeof\u64cd\u4f5c\u7b26;\u800c\u786e\u5b9a\u4e00\u4e2a\u503c\u662f\u54ea\u79cd\u5f15\u7528\u7c7b\u578b\u53ef\u4ee5\u4f7f\u7528instanceof\u64cd\u4f5c\u7b26;
\n2.\u4f5c\u7528\u57df\/\/ \u6240\u6709\u53d8\u91cf\u90fd\u5b58\u5728\u4e8e\u4e00\u4e2a\u6267\u884c\u73af\u5883(\u4f5c\u7528\u57df)\u4e2d,\u8fd9\u4e2a\u6267\u884c\u73af\u5883\u51b3\u5b9a\u4e86\u53d8\u91cf\u7684\u751f\u547d\u5468\u671f,\u4ee5\u53ca\u54ea\u4e00\u90e8\u5206\u4ee3\u7801\u53ef\u4ee5\u8bbf\u95ee\u5176\u4e2d\u7684\u53d8\u91cf; \/\/ 1.\u6267\u884c\u73af\u5883\u6709\u5168\u5c40\u6267\u884c\u73af\u5883\u548c\u51fd\u6570\u6267\u884c\u73af\u5883\u4e4b\u5206;\/\/ 2.\u6bcf\u6b21\u8fdb\u5165\u4e00\u4e2a\u65b0\u6267\u884c\u73af\u5883,\u90fd\u4f1a\u521b\u5efa\u4e00\u4e2a\u7528\u4e8e\u641c\u7d22\u53d8\u91cf\u548c\u51fd\u6570\u7684\u4f5c\u7528\u57df\u94fe;\/\/ 3.\u51fd\u6570\u7684\u5c40\u90e8\u73af\u5883\u4e0d\u4ec5\u6709\u6743\u8bbf\u95ee\u51fd\u6570\u4f5c\u7528\u57df\u4e2d\u7684\u53d8\u91cf\uff0c\u800c\u4e14\u6709\u6743\u8bbf\u95ee\u5176\u7236\u73af\u5883\uff0c\u4e43\u81f3\u5168\u5c40\u73af\u5883\uff1b\/\/ 4.\u53d8\u91cf\u7684\u6267\u884c\u73af\u5883\u6709\u52a9\u4e8e\u786e\u5b9a\u5e94\u8be5\u5408\u9002\u91ca\u653e\u5185\u5b58;
\n3.\u5185\u5b58\/\/ JS\u81ea\u52a8\u5783\u573e\u6536\u96c6\u673a\u5236\/\/ 1.\u79bb\u5f00\u4f5c\u7528\u57df\u7684\u503c\u5c06\u88ab\u81ea\u52a8\u6807\u8bb0\u4e3a\u53ef\u4ee5\u56de\u6536,\u56e0\u6b64\u5c06\u5728\u5783\u573e\u6536\u96c6\u671f\u95f4\u88ab\u5220\u9664;\/\/ 2.\u4e3a\u4e86\u786e\u4fdd\u6709\u6548\u5730\u56de\u6536\u5185\u5b58,\u5e94\u8be5\u53ca\u65f6\u89e3\u9664\u4e0d\u518d\u4f7f\u7528\u7684\u5168\u5c40\u5bf9\u8c61\/\u5168\u5c40\u5bf9\u8c61\u5c5e\u6027\u4ee5\u53ca\u5faa\u73af\u5f15\u7528\u53d8\u91cf\u7684\u5f15\u7528;<\/p>\n
\u6b22\u8fce\u5206\u4eab\u672c\u6587\uff0c\u8f6c\u8f7d\u8bf7\u4fdd\u7559\u51fa\u5904\uff1a\u524d\u7aefABC<\/a> » JavaScript \u53d8\u91cf\u3001\u4f5c\u7528\u57df\u53ca\u5185\u5b58<\/a><\/p>","protected":false},"excerpt":{"rendered":" javascript JS\u53d8\u91cf\u662f\u677e\u6563\u578b\u7684(\u4e0d\u5f3a\u5236\u7c7b\u578b)\u672c\u8d28,\u51b3\u5b9a\u4e86\u5b83\u53ea\u662f\u5728\u7279\u5b9a\u65f6\u95f4\u7528\u4e8e\u4fdd\u5b58\u7279\u5b9a\u503c\u7684\u4e00\u4e2a\u540d\u5b57\u800c\u5df2;\u7531\u4e8e\u4e0d\u5b58\u5728\u5b9a\u4e49\u67d0\u4e2a\u53d8\u91cf\u5fc5\u987b\u8981\u4fdd\u5b58\u4f55\u79cd\u6570\u636e\u7c7b\u578b\u503c\u7684\u89c4\u5219,\u53d8\u91cf\u7684\u503c\u53ca\u5176\u6570\u636e\u7c7b\u578b\u53ef\u4ee5\u5728\u811a\u672c\u7684\u751f […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[9,242,243,241],"_links":{"self":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts\/1766"}],"collection":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1766"}],"version-history":[{"count":1,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts\/1766\/revisions"}],"predecessor-version":[{"id":1767,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts\/1766\/revisions\/1767"}],"wp:attachment":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1766"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1766"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1766"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}