{"id":233516,"date":"2020-12-29T14:25:21","date_gmt":"2020-12-29T06:25:21","guid":{"rendered":"http:\/\/4563.org\/?p=233516"},"modified":"2020-12-29T14:25:21","modified_gmt":"2020-12-29T06:25:21","slug":"20-%e5%88%86%e9%92%9f%e5%b8%a6%e4%bd%a0%e6%8e%8c%e6%8f%a1-javascript-promise-%e5%92%8c-async-await","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=233516","title":{"rendered":"20 \u5206\u949f\u5e26\u4f60\u638c\u63e1 JavaScript Promise \u548c Async\/Await"},"content":{"rendered":"<div>\n<div>\n<div>\n<h1>                  20 \u5206\u949f\u5e26\u4f60\u638c\u63e1 JavaScript Promise \u548c Async\/Await               <\/h1>\n<p> <\/p>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : GrapeCityChina <\/span>  <span><i><\/i> 11<\/span> <\/div>\n<div> <\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<div isfirst=\"1\"> <\/p>\n<p>\u4e00\u822c\u5728\u5f00\u53d1\u4e2d\uff0c\u67e5\u8be2\u7f51\u7edc API \u64cd\u4f5c\u65f6\u5f80\u5f80\u662f\u6bd4\u8f83\u8017\u65f6\u7684\uff0c\u8fd9\u610f\u5473\u7740\u53ef\u80fd\u9700\u8981\u4e00\u6bb5\u65f6\u95f4\u7684\u7b49\u5f85\u624d\u80fd\u83b7\u5f97\u54cd\u5e94\u3002\u56e0\u6b64\uff0c\u4e3a\u4e86\u907f\u514d\u7a0b\u5e8f\u5728\u8bf7\u6c42\u65f6\u65e0\u54cd\u5e94\u7684\u60c5\u51b5\uff0c\u5f02\u6b65\u7f16\u7a0b\u5c31\u6210\u4e3a\u4e86\u5f00\u53d1\u4eba\u5458\u7684\u4e00\u9879\u57fa\u672c\u6280\u80fd\u3002<\/p>\n<p>\u5728 JavaScript \u4e2d\u5904\u7406\u5f02\u6b65\u64cd\u4f5c\u65f6\uff0c\u901a\u5e38\u6211\u4eec\u7ecf\u5e38\u4f1a\u542c\u5230 &#8220;Promise &#8220;\u8fd9\u4e2a\u6982\u5ff5\u3002\u4f46\u8981\u7406\u89e3\u5b83\u7684\u5de5\u4f5c\u539f\u7406\u53ca\u4f7f\u7528\u65b9\u6cd5\u53ef\u80fd\u4f1a\u6bd4\u8f83\u62bd\u8c61\u548c\u96be\u4ee5\u7406\u89e3\u3002<\/p>\n<p>\u90a3\u4e48\uff0c\u5728\u672c\u6587\u4e2d\u6211\u4eec\u5c06\u4f1a\u901a\u8fc7\u5b9e\u8df5\u7684\u65b9\u5f0f\u8ba9\u4f60\u80fd\u66f4\u5feb\u901f\u7684\u7406\u89e3\u5b83\u4eec\u7684\u6982\u5ff5\u548c\u7528\u6cd5\uff0c\u6240\u4ee5\u4e0e\u8bb8\u591a\u4f20\u7edf\u5e72\u5df4\u5df4\u7684\u6559\u7a0b\u90fd\u4e0d\u540c\uff0c\u6211\u4eec\u5c06\u901a\u8fc7\u4ee5\u4e0b\u56db\u4e2a\u793a\u4f8b\u5f00\u59cb\uff1a<\/p>\n<ul>\n<li>\u793a\u4f8b 1\uff1a\u7528\u751f\u65e5\u89e3\u91ca Promise \u7684\u57fa\u7840\u77e5\u8bc6<\/li>\n<li>\u793a\u4f8b 2\uff1a\u4e00\u4e2a\u731c\u6570\u5b57\u7684\u6e38\u620f<\/li>\n<li>\u793a\u4f8b 3\uff1a\u4ece Web API \u4e2d\u83b7\u53d6\u56fd\u5bb6\u4fe1\u606f<\/li>\n<li>\u793a\u4f8b 4\uff1a\u4ece Web API \u4e2d\u83b7\u53d6\u4e00\u4e2a\u56fd\u5bb6\u7684\u5468\u8fb9\u56fd\u5bb6\u5217\u8868<\/li>\n<\/ul>\n<h2>\u793a\u4f8b 1\uff1a\u7528\u751f\u65e5\u89e3\u91ca Promise \u57fa\u7840\u77e5\u8bc6<\/h2>\n<p>\u9996\u5148\uff0c\u6211\u4eec\u5148\u6765\u770b\u770b Promise \u7684\u57fa\u672c\u5f62\u6001\u662f\u4ec0\u4e48\u6837\u7684\u3002<\/p>\n<p>Promise \u6267\u884c\u65f6\u5206\u4e09\u4e2a\u72b6\u6001\uff1apending \uff08\u6267\u884c\u4e2d\uff09\u3001fulfilled \uff08\u6210\u529f\uff09\u3001rejected \uff08\u5931\u8d25\uff09\u3002<\/p>\n<pre><code>new Promise(function(resolve, reject) {     if (\/* \u5f02\u6b65\u64cd\u4f5c\u6210\u529f *\/) {         resolve(value); \/\/\u5c06 Promise \u7684\u72b6\u6001\u7531 padding \u6539\u4e3a fulfilled     } else {         reject(error); \/\/\u5c06 Promise \u7684\u72b6\u6001\u7531 padding \u6539\u4e3a rejected     } }) <\/code><\/pre>\n<p>\u5b9e\u73b0\u65f6\u6709\u4e09\u4e2a\u539f\u578b\u65b9\u6cd5 then \u3001catch \u3001finally<\/p>\n<pre><code>promise .then((result) =&gt; {  \/\/promise \u88ab\u63a5\u6536\u6216\u62d2\u7edd\u7ee7\u7eed\u6267\u884c\u7684\u60c5\u51b5 }) .catch((error) =&gt; {  \/\/promise \u88ab\u62d2\u7edd\u7684\u60c5\u51b5 }) .finally (() =&gt; {  \/\/promise \u5b8c\u6210\u65f6\uff0c\u65e0\u8bba\u5982\u4f55\u90fd\u4f1a\u6267\u884c\u7684\u60c5\u51b5 }) <\/code><\/pre>\n<p>\u57fa\u672c\u5f62\u6001\u4ecb\u7ecd\u5b8c\u6210\u4e86\uff0c\u90a3\u4e48\u6211\u4eec\u4e0b\u9762\u5f00\u59cb\u770b\u770b\u4e0b\u9762\u7684\u793a\u4f8b\u5427\u3002<\/p>\n<p>\u7528\u6237\u6545\u4e8b\uff1a\u6211\u7684\u670b\u53cb Kayo \u7b54\u5e94\u5728\u4e24\u5468\u540e\u5728\u6211\u7684\u751f\u65e5 Party \u4e0a\u4e3a\u6211\u505a\u4e00\u4e2a\u86cb\u7cd5\u3002<\/p>\n<p>\u5982\u679c\u4e00\u5207\u987a\u5229\u4e14 Kayo \u6ca1\u6709\u751f\u75c5\u7684\u8bdd\uff0c\u6211\u4eec\u5c31\u4f1a\u83b7\u5f97\u4e00\u5b9a\u6570\u91cf\u7684\u86cb\u7cd5\uff0c\u4f46\u5982\u679c Kayo \u751f\u75c5\u4e86\uff0c\u6211\u4eec\u5c31\u6ca1\u6709\u86cb\u7cd5\u4e86\u3002\u4f46\u4e0d\u8bba\u6709\u6ca1\u6709\u86cb\u7cd5\uff0c\u6211\u4eec\u4ecd\u7136\u4f1a\u5f00\u4e00\u4e2a\u751f\u65e5 Party \u3002<\/p>\n<p>\u6240\u4ee5\u5bf9\u4e8e\u8fd9\u4e2a\u793a\u4f8b\uff0c\u6211\u4eec\u5c06\u5982\u4e0a\u7684\u80cc\u666f\u6545\u4e8b\u7ffb\u8bd1\u6210 JS \u4ee3\u7801\uff0c\u9996\u5148\u8ba9\u6211\u4eec\u5148\u521b\u5efa\u4e00\u4e2a\u8fd4\u56de Promise \u7684\u51fd\u6570\u3002<\/p>\n<pre><code>const onMyBirthday = (isKayoSick) =&gt; {   return new Promise((resolve, reject) =&gt; {     setTimeout(() =&gt; {       if (!isKayoSick) {         resolve(2);       } else {         reject(new Error(\"I am sad\"));       }     }, 2000);   }); }; <\/code><\/pre>\n<p>\u5728 JavaScript \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 new Promise()\u521b\u5efa\u4e00\u4e2a\u65b0\u7684 Promise\uff0c\u5b83\u63a5\u53d7\u4e00\u4e2a\u53c2\u6570\u4e3a\uff1a(resolve\uff0creject)=&gt;{} \u7684\u51fd\u6570\u3002<\/p>\n<p>\u5728\u6b64\u51fd\u6570\u4e2d\uff0cresolve \u548c reject \u662f\u9ed8\u8ba4\u63d0\u4f9b\u7684\u56de\u8c03\u51fd\u6570\u3002\u8ba9\u6211\u4eec\u4ed4\u7ec6\u770b\u770b\u4e0a\u9762\u7684\u4ee3\u7801\u3002<\/p>\n<p>\u5f53\u6211\u4eec\u8fd0\u884c onMyBirthday \u51fd\u6570 2000ms \u540e\u3002<\/p>\n<ul>\n<li>\u5982\u679c Kayo \u6ca1\u6709\u751f\u75c5\uff0c\u90a3\u4e48\u6211\u4eec\u5c31\u4ee5 2 \u4e3a\u53c2\u6570\u6267\u884c resolve \u51fd\u6570<\/li>\n<li>\u5982\u679c Kayo \u751f\u75c5\u4e86\uff0c\u90a3\u4e48\u6211\u4eec\u7528 new Error(&#8220;I am sad&#8221;)\u4f5c\u4e3a\u53c2\u6570\u6267\u884c reject \u3002\u5c3d\u7ba1\u60a8\u53ef\u4ee5\u5c06\u4efb\u4f55\u8981\u62d2\u7edd\u7684\u5185\u5bb9\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\uff0c\u4f46\u5efa\u8bae\u5c06\u5176\u4f20\u9012\u7ed9 Error \u5bf9\u8c61\u3002<\/li>\n<\/ul>\n<p>\u73b0\u5728\uff0c\u56e0\u4e3a onMyBirthday()\u8fd4\u56de\u7684\u662f\u4e00\u4e2a Promise\uff0c\u6211\u4eec\u53ef\u4ee5\u8bbf\u95ee then \u3001catch \u548c finally \u65b9\u6cd5\u3002\u6211\u4eec\u8fd8\u53ef\u4ee5\u8bbf\u95ee\u65e9\u4e9b\u65f6\u5019\u5728 then \u548c catch \u4e2d\u4f7f\u7528\u4f20\u9012\u7ed9 resolve \u548c reject \u7684\u53c2\u6570\u3002<\/p>\n<p>\u8ba9\u6211\u4eec\u901a\u8fc7\u5982\u4e0b\u4ee3\u7801\u6765\u7406\u89e3\u6982\u5ff5<\/p>\n<p>\u5982\u679c Kayo \u6ca1\u6709\u751f\u75c5<\/p>\n<pre><code>onMyBirthday(false)   .then((result) =&gt; {     console.log(`I have ${result} cakes`); \/\/ \u63a7\u5236\u53f0\u6253\u5370\u201cI have 2 cakes\u201d     })   .catch((error) =&gt; {     console.log(error); \/\/ \u4e0d\u6267\u884c   })   .finally(() =&gt; {     console.log(\"Party\"); \/\/ \u63a7\u5236\u53f0\u6253\u5370\u201cParty\u201d   }); <\/code><\/pre>\n<p>\u5982\u679c Kayo \u751f\u75c5<\/p>\n<pre><code>onMyBirthday(true)   .then((result) =&gt; {     console.log(`I have ${result} cakes`); \/\/ \u4e0d\u6267\u884c    })   .catch((error) =&gt; {     console.log(error); \/\/ \u63a7\u5236\u53f0\u6253\u5370\u201c\u6211\u5f88\u96be\u8fc7\u201d   })   .finally(() =&gt; {     console.log(\"Party\"); \/\/ \u63a7\u5236\u53f0\u6253\u5370\u201cParty\u201d   }); <\/code><\/pre>\n<p>\u76f8\u4fe1\u901a\u8fc7\u8fd9\u4e2a\u4f8b\u5b50\u4f60\u80fd\u4e86\u89e3 Promise \u7684\u57fa\u672c\u6982\u5ff5\u3002<\/p>\n<p>\u4e0b\u9762\u6211\u4eec\u5f00\u59cb\u793a\u4f8b 2<\/p>\n<h2>\u793a\u4f8b 2\uff1a\u4e00\u4e2a\u731c\u6570\u5b57\u7684\u6e38\u620f<\/h2>\n<p>\u57fa\u672c\u9700\u6c42\uff1a<\/p>\n<ul>\n<li>\u7528\u6237\u53ef\u4ee5\u8f93\u5165\u4efb\u610f\u6570\u5b57<\/li>\n<li>\u7cfb\u7edf\u4ece 1 \u5230 6 \u4e2d\u968f\u673a\u751f\u6210\u4e00\u4e2a\u6570\u5b57<\/li>\n<li>\u5982\u679c\u7528\u6237\u8f93\u5165\u6570\u5b57\u7b49\u4e8e\u7cfb\u7edf\u968f\u673a\u6570\uff0c\u5219\u7ed9\u7528\u6237 2 \u5206<\/li>\n<li>\u5982\u679c\u7528\u6237\u8f93\u5165\u6570\u5b57\u4e0e\u7cfb\u7edf\u968f\u673a\u6570\u76f8\u5dee 1\uff0c\u7ed9\u7528\u6237 1 \u5206\uff0c\u5426\u5219\uff0c\u7ed9\u7528\u6237 0 \u5206<\/li>\n<li>\u7528\u6237\u60f3\u73a9\u591a\u4e45\u5c31\u73a9\u591a\u4e45<\/li>\n<\/ul>\n<p>\u5bf9\u4e8e\u4e0a\u9762\u7684\u9700\u6c42\uff0c\u6211\u4eec\u9996\u5148\u521b\u5efa\u4e00\u4e2a enterNumber \u51fd\u6570\u5e76\u8fd4\u56de\u4e00\u4e2a Promise\uff1a<\/p>\n<pre><code>const enterNumber = () =&gt; {   return new Promise((resolve, reject) =&gt; {     \/\/ \u4ece\u8fd9\u5f00\u59cb\u7f16\u7801   }); }; <\/code><\/pre>\n<p>\u6211\u4eec\u8981\u505a\u7684\u7b2c\u4e00\u4ef6\u4e8b\u662f\u5411\u7528\u6237\u7d22\u8981\u4e00\u4e2a\u6570\u5b57\uff0c\u5e76\u5728 1 \u5230 6 \u4e4b\u95f4\u968f\u673a\u9009\u62e9\u4e00\u4e2a\u6570\u5b57\uff1a<\/p>\n<pre><code>const enterNumber = () =&gt; {   return new Promise((resolve, reject) =&gt; {     const userNumber = Number(window.prompt(\"Enter a number (1 - 6):\")); \/\/ \u5411\u7528\u6237\u7d22\u8981\u4e00\u4e2a\u6570\u5b57     const randomNumber = Math.floor(Math.random() * 6 + 1); \/\/ \u9009\u62e9\u4e00\u4e2a\u4ece 1 \u5230 6 \u7684\u968f\u673a\u6570   }); }; <\/code><\/pre>\n<p>\u5f53\u7528\u6237\u8f93\u5165\u4e00\u4e2a\u4e0d\u662f\u6570\u5b57\u7684\u503c\u3002\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u8c03\u7528 reject \u51fd\u6570\uff0c\u5e76\u629b\u51fa\u9519\u8bef\uff1a<\/p>\n<pre><code>const enterNumber = () =&gt; {   return new Promise((resolve, reject) =&gt; {     const userNumber = Number(window.prompt(\"Enter a number (1 - 6):\")); \/\/ \u5411\u7528\u6237\u7d22\u8981\u4e00\u4e2a\u6570\u5b57     const randomNumber = Math.floor(Math.random() * 6 + 1); \/\/\u9009\u62e9\u4e00\u4e2a\u4ece 1 \u5230 6 \u7684\u968f\u673a\u6570      if (isNaN(userNumber)) {       reject(new Error(\"Wrong Input Type\")); \/\/ \u5f53\u7528\u6237\u8f93\u5165\u7684\u503c\u975e\u6570\u5b57\uff0c\u629b\u51fa\u5f02\u5e38\u5e76\u8c03\u7528 reject \u51fd\u6570     }   }); }; <\/code><\/pre>\n<p>\u4e0b\u9762\uff0c\u6211\u4eec\u9700\u8981\u68c0\u67e5 userNumber \u662f\u5426\u7b49\u4e8e RanomNumber\uff0c\u5982\u679c\u76f8\u7b49\uff0c\u6211\u4eec\u7ed9\u7528\u6237 2 \u5206\uff0c\u7136\u540e\u6211\u4eec\u53ef\u4ee5\u6267\u884c resolve \u51fd\u6570\u6765\u4f20\u9012\u4e00\u4e2a object { points: 2, randomNumber } \u5bf9\u8c61\u3002<\/p>\n<p>\u5982\u679c userNumber \u4e0e randomNumber \u76f8\u5dee 1\uff0c\u90a3\u4e48\u6211\u4eec\u7ed9\u7528\u6237 1 \u5206\u3002\u5426\u5219\uff0c\u6211\u4eec\u7ed9\u7528\u6237 0 \u5206\u3002<\/p>\n<pre><code>return new Promise((resolve, reject) =&gt; {   const userNumber = Number(window.prompt(\"Enter a number (1 - 6):\")); \/\/ \u5411\u7528\u6237\u7d22\u8981\u4e00\u4e2a\u6570\u5b57   const randomNumber = Math.floor(Math.random() * 6 + 1); \/\/ \u9009\u62e9\u4e00\u4e2a\u4ece 1 \u5230 6 \u7684\u968f\u673a\u6570    if (isNaN(userNumber)) {     reject(new Error(\"Wrong Input Type\")); \/\/ \u5f53\u7528\u6237\u8f93\u5165\u7684\u503c\u975e\u6570\u5b57\uff0c\u629b\u51fa\u5f02\u5e38\u5e76\u8c03\u7528 reject \u51fd\u6570   }    if (userNumber === randomNumber) {     \/\/ \u5982\u679c\u76f8\u7b49\uff0c\u6211\u4eec\u7ed9\u7528\u6237 2 \u5206     resolve({       points: 2,       randomNumber,     });   } else if (     userNumber === randomNumber - 1 ||     userNumber === randomNumber + 1   ) {     \/\/ \u5982\u679c userNumber \u4e0e randomNumber \u76f8\u5dee 1\uff0c\u90a3\u4e48\u6211\u4eec\u7ed9\u7528\u6237 1 \u5206     resolve({       points: 1,       randomNumber,     });   } else {     \/\/ \u5426\u5219\u7528\u6237\u5f97 0 \u5206     resolve({       points: 0,       randomNumber,     });   } }); <\/code><\/pre>\n<p>\u4e0b\u9762\uff0c\u8ba9\u6211\u4eec\u518d\u521b\u5efa\u4e00\u4e2a\u51fd\u6570\u6765\u8be2\u95ee\u7528\u6237\u662f\u5426\u60f3\u7ee7\u7eed\u6e38\u620f\uff1a<\/p>\n<pre><code>const continueGame = () =&gt; {   return new Promise((resolve) =&gt; {     if (window.confirm(\"Do you want to continue?\")) { \/\/ \u5411\u7528\u6237\u8be2\u95ee\u662f\u5426\u8981\u7ee7\u7eed\u6e38\u620f       resolve(true);     } else {       resolve(false);     }   }); }; <\/code><\/pre>\n<p>\u4e3a\u4e86\u4e0d\u4f7f\u6e38\u620f\u5f3a\u5236\u7ed3\u675f\uff0c\u6211\u4eec\u521b\u5efa\u7684 Promise \u6ca1\u6709\u4f7f\u7528 Reject \u56de\u8c03\u3002<\/p>\n<p>\u4e0b\u9762\uff0c\u6211\u4eec\u521b\u5efa\u4e00\u4e2a\u51fd\u6570\u6765\u5904\u7406\u731c\u6570\u5b57\u903b\u8f91\uff1a<\/p>\n<pre><code>const handleGuess = () =&gt; {   enterNumber() \/\/ \u8fd4\u56de\u4e00\u4e2a Promise \u5bf9\u8c61     .then((result) =&gt; {       alert(`Dice: ${result.randomNumber}: you got ${result.points} points`); \/\/ \u5f53 resolve \u8fd0\u884c\u65f6\uff0c\u6211\u4eec\u5f97\u5230\u7528\u6237\u5f97\u5206\u548c\u968f\u673a\u6570               \/\/ \u5411\u7528\u6237\u8be2\u95ee\u662f\u5426\u8981\u7ee7\u7eed\u6e38\u620f       continueGame().then((result) =&gt; {         if (result) {           handleGuess(); \/\/ If yes, \u6e38\u620f\u7ee7\u7eed         } else {           alert(\"Game ends\"); \/\/ If no, \u5f39\u51fa\u6e38\u620f\u7ed3\u675f\u6846         }       });     })     .catch((error) =&gt; alert(error)); };  handleGuess(); \/\/ \u6267\u884c handleGuess \u51fd\u6570 <\/code><\/pre>\n<p>\u5728\u8fd9\u5f53\u6211\u4eec\u8c03\u7528 handleGuess \u51fd\u6570\u65f6\uff0centerNumber()\u8fd4\u56de\u4e00\u4e2a Promise \u5bf9\u8c61\u3002<\/p>\n<p>\u5982\u679c Promise \u72b6\u6001\u4e3a resolved\uff0c\u6211\u4eec\u5c31\u8c03\u7528 then \u65b9\u6cd5\uff0c\u5411\u7528\u6237\u544a\u77e5\u7ade\u731c\u7ed3\u679c\u4e0e\u5f97\u5206\uff0c\u5e76\u5411\u7528\u6237\u8be2\u95ee\u662f\u5426\u8981\u7ee7\u7eed\u6e38\u620f\u3002<\/p>\n<p>\u5982\u679c Promise \u72b6\u6001\u4e3a rejected\uff0c\u6211\u4eec\u5c06\u663e\u793a\u4e00\u6761\u7528\u6237\u8f93\u5165\u9519\u8bef\u7684\u4fe1\u606f\u3002<\/p>\n<p>\u4e0d\u8fc7\uff0c\u8fd9\u6837\u7684\u4ee3\u7801\u867d\u7136\u80fd\u89e3\u51b3\u95ee\u9898\uff0c\u4f46\u8bfb\u8d77\u6765\u8fd8\u662f\u6709\u70b9\u56f0\u96be\u3002\u8ba9\u6211\u4eec\u540e\u9762\u5c06\u4f7f\u7528 async\/await \u5bf9 hanldeGuess \u8fdb\u884c\u91cd\u6784\u3002<\/p>\n<p>\u7f51\u4e0a\u5bf9\u4e8e async\/await \u7684\u89e3\u91ca\u5df2\u7ecf\u5f88\u591a\u4e86\uff0c\u5728\u8fd9\u6211\u60f3\u7528\u4e00\u4e2a\u7b80\u5355\u6982\u62ec\u7684\u8bf4\u6cd5\u6765\u89e3\u91ca\uff1a<strong>async\/await \u5c31\u662f\u53ef\u4ee5\u628a\u590d\u6742\u96be\u61c2\u7684\u5f02\u6b65\u4ee3\u7801\u53d8\u6210\u7c7b\u540c\u6b65\u8bed\u6cd5\u7684\u8bed\u6cd5\u7cd6<\/strong>\u3002<\/p>\n<p>\u4e0b\u9762\u5f00\u59cb\u770b\u91cd\u6784\u540e\u4ee3\u7801\u5427\uff1a<\/p>\n<pre><code>const handleGuess = async () =&gt; {   try {     const result = await enterNumber(); \/\/ \u4ee3\u66ff then \u65b9\u6cd5\uff0c\u6211\u4eec\u53ea\u9700\u5c06 await \u653e\u5728 promise \u524d\uff0c\u5c31\u53ef\u4ee5\u76f4\u63a5\u83b7\u5f97\u7ed3\u679c      alert(`Dice: ${result.randomNumber}: you got ${result.points} points`);      const isContinuing = await continueGame();      if (isContinuing) {       handleGuess();     } else {       alert(\"Game ends\");     }   } catch (error) { \/\/ catch \u65b9\u6cd5\u53ef\u4ee5\u7531 try, catch \u51fd\u6570\u6765\u66ff\u4ee3     alert(error);   } }; <\/code><\/pre>\n<p>\u901a\u8fc7\u5728\u51fd\u6570\u524d\u4f7f\u7528 async \u5173\u952e\u5b57\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u5f02\u6b65\u51fd\u6570\uff0c\u5728\u51fd\u6570\u5185\u7684\u4f7f\u7528\u65b9\u6cd5\u8f83\u4e4b\u524d\u6709\u5982\u4e0b\u4e0d\u540c\uff1a<\/p>\n<ul>\n<li>\u548c then \u51fd\u6570\u4e0d\u540c\uff0c\u6211\u4eec\u53ea\u9700\u5c06 await \u5173\u952e\u5b57\u653e\u5728 Promise \u524d\uff0c\u5c31\u53ef\u4ee5\u76f4\u63a5\u83b7\u5f97\u7ed3\u679c\u3002<\/li>\n<li>\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 try, catch \u8bed\u6cd5\u6765\u4ee3\u66ff promise \u4e2d\u7684 catch \u65b9\u6cd5\u3002<\/li>\n<\/ul>\n<p>\u4e0b\u9762\u662f\u6211\u4eec\u91cd\u6784\u540e\u7684\u5b8c\u6574\u4ee3\u7801\uff0c\u4f9b\u53c2\u8003\uff1a<\/p>\n<pre><code>const enterNumber = () =&gt; {   return new Promise((resolve, reject) =&gt; {     const userNumber = Number(window.prompt(\"Enter a number (1 - 6):\")); \/\/ \u5411\u7528\u6237\u7d22\u8981\u4e00\u4e2a\u6570\u5b57     const randomNumber = Math.floor(Math.random() * 6 + 1); \/\/ \u7cfb\u7edf\u968f\u673a\u9009\u53d6\u4e00\u4e2a 1-6 \u7684\u6570\u5b57      if (isNaN(userNumber)) {       reject(new Error(\"Wrong Input Type\")); \/\/ \u5982\u679c\u7528\u6237\u8f93\u5165\u975e\u6570\u5b57\u629b\u51fa\u9519\u8bef     }      if (userNumber === randomNumber) { \/\/ \u5982\u679c\u7528\u6237\u731c\u6570\u5b57\u6b63\u786e\uff0c\u7ed9\u7528\u6237 2 \u5206       resolve({         points: 2,         randomNumber,       });     } else if (       userNumber === randomNumber - 1 ||       userNumber === randomNumber + 1     ) { \/\/ \u5982\u679c userNumber \u4e0e randomNumber \u76f8\u5dee 1\uff0c\u90a3\u4e48\u6211\u4eec\u7ed9\u7528\u6237 1 \u5206       resolve({         points: 1,         randomNumber,       });     } else { \/\/ \u4e0d\u6b63\u786e\uff0c\u5f97 0 \u5206       resolve({         points: 0,         randomNumber,       });     }   }); };  const continueGame = () =&gt; {   return new Promise((resolve) =&gt; {     if (window.confirm(\"Do you want to continue?\")) { \/\/ \u5411\u7528\u6237\u8be2\u95ee\u662f\u5426\u8981\u7ee7\u7eed\u6e38\u620f       resolve(true);     } else {       resolve(false);     }   }); };  const handleGuess = async () =&gt; {   try {     const result = await enterNumber(); \/\/ await \u66ff\u4ee3\u4e86 then \u51fd\u6570      alert(`Dice: ${result.randomNumber}: you got ${result.points} points`);      const isContinuing = await continueGame();      if (isContinuing) {       handleGuess();     } else {       alert(\"Game ends\");     }   } catch (error) { \/\/ catch \u65b9\u6cd5\u53ef\u4ee5\u7531 try, catch \u51fd\u6570\u6765\u66ff\u4ee3     alert(error);   } };  handleGuess(); \/\/ \u6267\u884c handleGuess \u51fd\u6570 <\/code><\/pre>\n<p>\u6211\u4eec\u5df2\u7ecf\u5b8c\u6210\u4e86\u7b2c\u4e8c\u4e2a\u793a\u4f8b\uff0c\u63a5\u4e0b\u6765\u8ba9\u6211\u4eec\u5f00\u59cb\u770b\u770b\u7b2c\u4e09\u4e2a\u793a\u4f8b\u3002<\/p>\n<h2>\u793a\u4f8b 3\uff1a\u4ece Web API \u4e2d\u83b7\u53d6\u56fd\u5bb6\u4fe1\u606f<\/h2>\n<p>\u4e00\u822c\u5f53\u4ece API \u4e2d\u83b7\u53d6\u6570\u636e\u65f6\uff0c\u5f00\u53d1\u4eba\u5458\u4f1a\u7cbe\u5f69\u4f7f\u7528 Promises \u3002\u5982\u679c\u5728\u65b0\u7a97\u53e3\u6253\u5f00 https:\/\/restcountries.eu\/rest\/v2\/alpha\/cn\uff0c\u4f60\u4f1a\u770b\u5230 JSON \u683c\u5f0f\u7684\u56fd\u5bb6\u6570\u636e\u3002<\/p>\n<p>\u901a\u8fc7\u4f7f\u7528Fetch API\uff0c\u6211\u4eec\u53ef\u4ee5\u5f88\u8f7b\u677e\u7684\u83b7\u5f97\u6570\u636e\uff0c\u4ee5\u4e0b\u662f\u4ee3\u7801\uff1a<\/p>\n<pre><code>const fetchData = async () =&gt; {   const res = await fetch(\"https:\/\/restcountries.eu\/rest\/v2\/alpha\/cn\"); \/\/ fetch() returns a promise, so we need to wait for it    const country = await res.json(); \/\/ res is now only an HTTP response, so we need to call res.json()    console.log(country); \/\/ China's data will be logged to the dev console };  fetchData(); <\/code><\/pre>\n<p>\u73b0\u5728\u6211\u4eec\u83b7\u5f97\u4e86\u6240\u9700\u7684\u56fd\u5bb6 \/\u5730\u533a\u6570\u636e\uff0c\u8ba9\u6211\u4eec\u8f6c\u5230\u6700\u540e\u4e00\u9879\u4efb\u52a1\u3002<\/p>\n<h2>\u793a\u4f8b 4\uff1a\u4ece Web API \u4e2d\u83b7\u53d6\u4e00\u4e2a\u56fd\u5bb6\u7684\u5468\u8fb9\u56fd\u5bb6\u5217\u8868<\/h2>\n<p>\u4e0b\u9762\u7684 fetchCountry \u51fd\u6570\u4ece\u793a\u4f8b 3 \u4e2d\u7684 api \u83b7\u5f97\u56fd\u5bb6\u4fe1\u606f\uff0c\u5176\u4e2d\u7684\u53c2\u6570 alpha3Code \u662f\u4ee3\u6307\u8be5\u56fd\u5bb6\u7684\u56fd\u5bb6\u4ee3\u7801\uff0c\u4ee5\u4e0b\u662f\u4ee3\u7801<\/p>\n<pre><code>\/\/ Task 4: \u83b7\u5f97\u4e2d\u56fd\u5468\u8fb9\u7684\u90bb\u56fd\u4fe1\u606f const fetchCountry = async (alpha3Code) =&gt; {   try {     const res = await fetch(       `https:\/\/restcountries.eu\/rest\/v2\/alpha\/${alpha3Code}`     );      const data = await res.json();      return data;   } catch (error) {     console.log(error);   } }; <\/code><\/pre>\n<p>\u4e0b\u9762\u8ba9\u6211\u4eec\u521b\u5efa\u4e00\u4e2a fetchCountryAndNeighbors \u51fd\u6570\uff0c\u901a\u8fc7\u4f20\u9012 cn \u4f5c\u4e3a alpha3code \u6765\u83b7\u53d6\u4e2d\u56fd\u7684\u4fe1\u606f\u3002<\/p>\n<pre><code>const fetchCountryAndNeighbors = async () =&gt; {   const china= await fetchCountry(\"cn\");    console.log(china); };  fetchCountryAndNeighbors(); <\/code><\/pre>\n<p>\u5728\u63a7\u5236\u53f0\u4e2d\uff0c\u6211\u4eec\u770b\u770b\u5bf9\u8c61\u5185\u5bb9\uff1a<\/p>\n<p><img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2020\/12\/20201230_5fec1d570a539.png\" alt=\"20 \u5206\u949f\u5e26\u4f60\u638c\u63e1 JavaScript Promise \u548c Async\/Await\" \/><\/p>\n<p>\u5728\u5bf9\u8c61\u4e2d\uff0c\u6709\u4e00\u4e2a border \u5c5e\u6027\uff0c\u5b83\u662f\u4e2d\u56fd\u5468\u8fb9\u90bb\u56fd\u7684 alpha3codes \u5217\u8868\u3002<\/p>\n<p>\u73b0\u5728\uff0c\u5982\u679c\u6211\u4eec\u5c1d\u8bd5\u901a\u8fc7\u4ee5\u4e0b\u65b9\u5f0f\u83b7\u53d6\u90bb\u56fd\u4fe1\u606f\u3002<\/p>\n<pre><code>const neighbors =      china.borders.map((border) =&gt; fetchCountry(border)); <\/code><\/pre>\n<p>neighbors \u662f\u4e00\u4e2a Promise \u5bf9\u8c61\u7684\u6570\u7ec4\u3002<\/p>\n<p>\u5f53\u5904\u7406\u4e00\u4e2a\u6570\u7ec4\u7684 Promise \u65f6\uff0c\u6211\u4eec\u9700\u8981\u4f7f\u7528 Promise.all \u3002<\/p>\n<pre><code>const fetchCountryAndNeigbors = async () =&gt; {   const china = await fetchCountry(\"cn\");    const neighbors = await Promise.all(     china.borders.map((border) =&gt; fetchCountry(border))   );    console.log(neighbors); };  fetchCountryAndNeigbors(); <\/code><\/pre>\n<p>\u5728\u63a7\u5236\u53f0\u4e2d\uff0c\u6211\u4eec\u5e94\u8be5\u80fd\u591f\u770b\u5230\u56fd\u5bb6 \/\u5730\u533a\u5bf9\u8c61\u5217\u8868\u3002<\/p>\n<p><img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2020\/12\/20201230_5fec1d5b0a33c.png\" alt=\"20 \u5206\u949f\u5e26\u4f60\u638c\u63e1 JavaScript Promise \u548c Async\/Await\" \/><\/p>\n<p>\u4ee5\u4e0b\u662f\u793a\u4f8b 4 \u7684\u6240\u6709\u4ee3\u7801\uff0c\u4f9b\u60a8\u53c2\u8003\uff1a<\/p>\n<pre><code>const fetchCountry = async (alpha3Code) =&gt; {   try {     const res = await fetch(       `https:\/\/restcountries.eu\/rest\/v2\/alpha\/${alpha3Code}`     );     const data = await res.json();     return data;   } catch (error) {     console.log(error);   } };  const fetchCountryAndNeigbors = async () =&gt; {   const china = await fetchCountry(\"cn\");   const neighbors = await Promise.all(     china.borders.map((border) =&gt; fetchCountry(border))   );   console.log(neighbors); };  fetchCountryAndNeigbors(); <\/code><\/pre>\n<h2>\u603b\u7ed3<\/h2>\n<p>\u5b8c\u6210\u8fd9 4 \u4e2a\u793a\u4f8b\u540e\uff0c\u4f60\u53ef\u4ee5\u770b\u5230 Promise \u5728\u5904\u7406\u5f02\u6b65\u64cd\u4f5c\u6216\u4e0d\u662f\u540c\u65f6\u53d1\u751f\u7684\u4e8b\u60c5\u65f6\u5f88\u6709\u7528\u3002\u76f8\u4fe1\u5728\u4e0d\u65ad\u7684\u5b9e\u8df5\u4e2d\uff0c\u5bf9\u5b83\u7684\u7406\u89e3\u4f1a\u8d8a\u6df1\u3001\u8d8a\u5f3a\uff0c\u5e0c\u671b\u8fd9\u7bc7\u6587\u7ae0\u80fd\u5bf9\u5927\u5bb6\u7406\u89e3 Promise \u548c Async\/Await \u5e26\u6765\u4e00\u4e9b\u5e2e\u52a9\u3002<\/p>\n<p>\u4ee5\u4e0b\u662f\u672c\u6587\u4e2d\u4f7f\u7528\u7684\u4ee3\u7801\uff1a<\/p>\n<p>Promise-Async-Await-main.zip<\/p>\n<\/p><\/div>\n<div> <b>\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (<span>5<\/span>)        <\/div>\n<div> <\/div>\n<\/p><\/div>\n<\/p><\/div>\n<ul>\n<li data-pid=\"4546844\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : GrapeCityChina <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u6269\u5c55\u9605\u8bfb\uff1a\u63a8\u8350\u4e00\u6b3e\u529f\u80fd\u5e03\u5c40\u4e0e Excel \u9ad8\u5ea6\u7c7b\u4f3c\u7684\u7eaf\u524d\u7aef\u8868\u683c\u63a7\u4ef6 SpreadJS \uff08 https:\/\/www.grapecity.com.cn\/developer\/spreadjs \uff09                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"4546845\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : Incrus <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             &#8220;` const data = await res.json(); &#8220;`<br \/>\u4e3a\u5565\u8f6c json \u4e5f\u8981 \u52a0 await \uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"4546846\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : Hanser002 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @Incrus <br \/>Body mixin \u7684 json() \u65b9\u6cd5\u63a5\u6536\u4e00\u4e2a Response \u6d41\uff0c\u5e76\u5c06\u5176\u8bfb\u53d6\u5b8c\u6210\u3002\u5b83\u8fd4\u56de\u4e00\u4e2a Promise\uff0cPromise \u7684\u89e3\u6790 resolve \u7ed3\u679c\u662f\u5c06\u6587\u672c\u4f53\u89e3\u6790\u4e3a JSON \u3002<br \/>https:\/\/developer.mozilla.org\/zh-CN\/docs\/Web\/API\/Body\/json                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"4546847\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : Incrus <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @Hanser002 3Q                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"4546848\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : rodrick <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u591a\u8c22\uff0c\u770b\u5b8c\u4ee5\u540e\u5df2\u7ecf\u80fd\u95ed\u7740\u773c\u624b\u5199 promise \u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li>\n","protected":false},"excerpt":{"rendered":"<p>20 \u5206\u949f\u5e26\u4f60\u638c\u63e1 JavaScr&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/233516"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=233516"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/233516\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=233516"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=233516"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=233516"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}