{"id":4773,"date":"2022-03-27T20:53:19","date_gmt":"2022-03-27T12:53:19","guid":{"rendered":"https:\/\/egonlin.com\/?p=4773"},"modified":"2022-03-27T20:53:19","modified_gmt":"2022-03-27T12:53:19","slug":"%e7%ac%ac%e4%b8%89%e8%8a%82%ef%bc%9ajs%e5%9f%ba%e7%a1%80%e8%af%ad%e6%b3%95","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=4773","title":{"rendered":"\u7b2c\u4e09\u8282\uff1ajs\u57fa\u7840\u8bed\u6cd5"},"content":{"rendered":"

js\u57fa\u7840\u8bed\u6cd5<\/h1>\n

1\u3001\u5206\u652f\u7ed3\u6784<\/h2>\n

1-1 if \u57fa\u7840\u8bed\u6cd5<\/h3>\n
if (\u6761\u4ef6\u8868\u8fbe\u5f0f) {\n    \u4ee3\u7801\u5757;\n}\n\/\/ 1. \u5f53\u6761\u4ef6\u8868\u8fbe\u5f0f\u7ed3\u679c\u4e3atrue\uff0c\u4f1a\u6267\u884c\u4ee3\u7801\u5757\uff1b\u53cd\u4e4b\u4e0d\u6267\u884c\n\/\/ 2. \u6761\u4ef6\u8868\u8fbe\u5f0f\u53ef\u4ee5\u4e3a\u666e\u901a\u8868\u8fbe\u5f0f\n\/\/ 3. 0\u3001undefined\u3001null\u3001""\u3001NaN\u4e3a\u5047\uff0c\u5176\u4ed6\u5747\u4e3a\u771f<\/code><\/pre>\n
1-2 if \u590d\u6742\u8bed\u6cd5<\/h3>\n
\/\/ 1.\u53cc\u5206\u652f\nif (\u8868\u8fbe\u5f0f1) {\n    \u4ee3\u7801\u57571;\n} else {\n    \u4ee3\u7801\u57572;\n}\n\n\/\/ 2.\u591a\u5206\u652f\nif (\u8868\u8fbe\u5f0f1) {\n\n} else if (\u8868\u8fbe\u5f0f2) {\n\n} \n...\nelse if (\u8868\u8fbe\u5f0f2) {\n\n} else {\n\n}<\/code><\/pre>\n
1-3 if \u5d4c\u5957<\/h3>\n
if (\u8868\u8fbe\u5f0f1) {\n    if (\u8868\u8fbe\u5f0f2) {\n\n    }\n}<\/code><\/pre>\n
1-4 \u6848\u4f8b\uff1a<\/h3>\n
var weather = prompt("\u5929\u6c14(\u6674|\u96e8)");  \/\/ \u6587\u672c\u8f93\u5165\u5f39\u51fa\u6846\nif (weather == "\u6674") {\n    alert("\u4eca\u5929\u662f\u6674\u5929")\n} else if (weather == "\u96e8") {\n    alert("\u4eca\u5929\u662f\u96e8\u5929")\n} else {\n    alert("\u8f93\u5165\u4fe1\u606f\u6709\u8bef")\n}<\/code><\/pre>\n
2\u3001\u5faa\u73af\u7ed3\u6784<\/h2>\n
2-1 or\u5faa\u73af<\/h3>\n
for (\u5faa\u73af\u53d8\u91cf\u2460; \u6761\u4ef6\u8868\u8fbe\u5f0f\u2461; \u5faa\u73af\u53d8\u91cf\u589e\u91cf\u2462) {\n    \u4ee3\u7801\u5757\u2463;\n}\n\/\/ for\u5faa\u73af\u6267\u884c\u7684\u987a\u5e8f\uff1a\u2460 \u2461\u2463\u2462 ... \u2461\u2463\u2462 \u2461\uff0c\u5165\u53e3\u4e3a\u2460\uff0c\u51fa\u53e3\u4e3a\u2461\uff0c\u2461\u2463\u2462\u5c31\u662f\u5faa\u73af\u8fc7\u7a0b\n\n\/\/ \u6848\u4f8b\uff1a\nfor (var i = 0; i < 5; i++) {\n    console.log(i);\n}\n\n\/\/ \u7ed3\u679c\uff1a\n0\n1\n2\n3\n4<\/code><\/pre>\n
2-2 while\u5faa\u73af<\/h3>\n
while (\u6761\u4ef6\u8868\u8fbe\u5f0f) {\n    \u4ee3\u7801\u5757;\n}\n\/\/ \u6761\u4ef6\u6ee1\u8db3\u6267\u884c\u4ee3\u7801\u5757\uff0c\u6761\u4ef6\u4e0d\u6ee1\u8db3\u8df3\u51fa\u5faa\u73af\n\n\/\/ \u6848\u4f8b\uff1a\nvar i = 0;\nwhile (i < 5) {\n    console.log(i);\n    i++;\n}\n\n\/\/ \u7ed3\u679c\uff1a\n0\n1\n2\n3\n4<\/code><\/pre>\n
2-3 for\u2026in\u8fed\u4ee3\u5668<\/h3>\n
var arr = [1, 2, 3, 4, 5]\nfor (num in arr) {\n    console.log(num);\n}\n\n\/\/ \u7ed3\u679c\uff1a\n0\n1\n2\n3\n4<\/code><\/pre>\n
2-4 break\uff0ccontinue\u5173\u952e\u8bcd<\/h3>\n
\/\/ 1. break\uff1a\u7ed3\u675f\u672c\u5c42\u5faa\u73af\n\/\/ 2. continue\uff1a\u7ed3\u675f\u672c\u6b21\u5faa\u73af\u8fdb\u5165\u4e0b\u4e00\u6b21\u5faa\u73af<\/code><\/pre>\n
3\u3001 JavaScript \u5bf9\u8c61<\/h2>\n
3-1 Object\u7c7b\u578b<\/h3>\n
\u521b\u5efa<\/h4>\n
    \n
  • \n
    \u76f4\u63a5\u91cf<\/p>\n
    var obj = {name:'xiaolili', age:100, getInfo:function(\n             console.log(this.age)\n         )}<\/code><\/pre>\n<\/li>\n
  • \n
    new \u6784\u9020\u51fd\u6570<\/p>\n
    var obj = new Object()\nobj.name = 'xiaolili'\nobj.age = 100<\/code><\/pre>\n<\/li>\n<\/ul>\n
    \u5c5e\u6027\u64cd\u4f5c<\/h4>\n
      \n
    • \n
      \u8bfb\u53d6\u6216\u4fee\u6539\u5c5e\u6027<\/p>\n
      console.log(obj.name)\nobj.name = 'lili'\n\nconsole.log(obj['name'])\nobj['name'] = 'honghong'<\/code><\/pre>\n<\/li>\n
    • \n
      \u5220\u9664\u5c5e\u6027<\/p>\n
      delete obj['name']\ndelete obj.name<\/code><\/pre>\n<\/li>\n
    • \n
      \u76d1\u6d4b\u5c5e\u6027\u662f\u5426\u51fa\u5b58\u5728<\/p>\n
      'name' in obj<\/code><\/pre>\n<\/li>\n<\/ul>\n
      3-2 \u58f0\u660e\u7c7b(\u6784\u9020\u51fd\u6570)<\/h3>\n
      function User(name, age){\n    this.name = name\n    this.age = age\n\n    this.getInfo = function(){\n        console.log(this.name, this.age)\n    }\n}\n\nvar u = new User('\u9c81\u8fc5', 45)<\/code><\/pre>\n
        \n
      • \u6bcf\u4e2a\u5bf9\u8c61\u90fd\u6709\u4e00\u4e2a\u5c5e\u6027 .constructor<\/code> \u4ece\u800c\u83b7\u53d6\u5176\u6784\u9020\u51fd\u6570<\/li>\n
      • \u4f7f\u7528\u8fd0\u7b97\u7b26instanceof<\/code>\u53ef\u4ee5\u5224\u65ad\u4e00\u4e2a\u5bf9\u8c61\u662f\u5426\u5c5e\u4e8e\u67d0\u4e2a\u6784\u9020\u51fd\u6570<\/li>\n<\/ul>\n
        3-3 this<\/h3>\n
          \n
        • this\u8868\u793a\u65b9\u6cd5 \u6240\u5c5e\u7684\u5bf9\u8c61<\/li>\n
        • \u5168\u5c40\u51fd\u6570\u4e2d\u7684this \u6307\u5411 window<\/li>\n<\/ul>\n
          3-4 \u539f\u578b\u548c\u539f\u578b\u94fe<\/h3>\n
          \u4ec0\u4e48\u662f\u539f\u578b<\/h4>\n
          \u6bcf\u4e00\u4e2aJavaScript\u5bf9\u8c61\u90fd\u548c\u53e6\u4e00\u4e2a\u5bf9\u8c61\u76f8\u5173\u8054, \u5e76\u4ece\u53e6\u4e00\u4e2a\u5bf9\u8c61\u7ee7\u627f\u5c5e\u6027,\u53e6\u4e00\u4e2a\u5bf9\u8c61\u5c31\u662f"\u539f\u578b"
          \n\u7528\u76f4\u63a5\u91cf\u521b\u5efa\u7684\u5bf9\u8c61 \u90fd\u5177\u6709\u540c\u4e00\u4e2a\u539f\u578b\u5bf9\u8c61 Object.prototype<\/p>\n
          \u539f\u578b\u94fe<\/h4>\n
          \u5bf9\u8c61\u7684\u539f\u578b\u4e5f\u6709\u539f\u578b,\u6784\u6210\u4e86\u539f\u578b\u94fe<\/p>\n
          \u83b7\u53d6\u539f\u578b<\/h4>\n
          \u6784\u9020\u51fd\u6570.prototype    \n\u5bf9\u8c61.__proto__<\/code><\/pre>\n
          \u7ed9\u539f\u578b\u6dfb\u52a0\u5c5e\u6027\u6216\u65b9\u6cd5<\/h4>\n
          \u7ed9\u539f\u578b\u6dfb\u52a0\u5c5e\u6027\u548c\u65b9\u6cd5\uff0c\u4ee5\u8be5\u5bf9\u8c61\u4e3a\u539f\u578b\u7684\u5bf9\u8c61 \u90fd\u53ef\u4ee5\u4f7f\u7528\u8be5\u65b9\u6cd5<\/p>\n
          \u68c0\u6d4b\u5c5e\u6027 \u662f\u81ea\u6709\u5c5e\u6027\u8fd8\u662f\u7ee7\u627f\u81ea\u539f\u578b\u7684\u5c5e\u6027<\/h4>\n
          obj.hasOwnProperty(proName)<\/code><\/pre>\n
          \u521b\u5efa\u5bf9\u8c61\u65f6\u6307\u5b9a\u539f\u578b<\/h4>\n
          Object.create(\u539f\u578b\u5bf9\u8c61)<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
          js\u57fa\u7840\u8bed\u6cd5 1\u3001\u5206\u652f\u7ed3\u6784 1-1 if \u57fa\u7840\u8bed\u6cd5 if (\u6761\u4ef6\u8868\u8fbe\u5f0f) { \u4ee3\u7801\u5757; } \/\/ 1. \u5f53\u6761\u4ef6 […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[361,366],"tags":[],"_links":{"self":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/4773"}],"collection":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4773"}],"version-history":[{"count":0,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/4773\/revisions"}],"wp:attachment":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4773"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4773"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4773"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}