{"id":1796,"date":"2021-02-08T22:40:23","date_gmt":"2021-02-08T14:40:23","guid":{"rendered":"http:\/\/123.57.164.21\/?p=1796"},"modified":"2021-02-08T22:40:23","modified_gmt":"2021-02-08T14:40:23","slug":"promise%e4%bb%8b%e7%bb%8d","status":"publish","type":"post","link":"https:\/\/92it.top\/?p=1796","title":{"rendered":"Promise\u4ecb\u7ecd"},"content":{"rendered":"\n

\u53bb\u5e746\u6708\u4efd\uff0c ES2015\u6b63\u5f0f\u53d1\u5e03\uff08\u4e5f\u5c31\u662fES6\uff0cES6\u662f\u5b83\u7684\u4e73\u540d\uff09\uff0c\u5176\u4e2dPromise\u88ab\u5217\u4e3a\u6b63\u5f0f\u89c4\u8303\u3002\u4f5c\u4e3aES6\u4e2d\u6700\u91cd\u8981\u7684\u7279\u6027\u4e4b\u4e00\uff0c\u6211\u4eec\u6709\u5fc5\u8981\u638c\u63e1\u5e76\u7406\u89e3\u900f\u5f7b\u3002\u672c\u6587\u5c06\u7531\u6d45\u5230\u6df1\uff0c\u8bb2\u89e3Promise\u7684\u57fa\u672c\u6982\u5ff5\u4e0e\u4f7f\u7528\u65b9\u6cd5\u3002<\/p>\n\n\n\n

ES6 Promise \u5148\u62c9\u51fa\u6765\u905b\u905b<\/strong><\/p>\n\n\n\n

\u590d\u6742\u7684\u6982\u5ff5\u5148\u4e0d\u8bb2\uff0c\u6211\u4eec\u5148\u7b80\u5355\u7c97\u66b4\u5730\u628aPromise\u7528\u4e00\u4e0b\uff0c\u6709\u4e2a\u76f4\u89c2\u611f\u53d7\u3002\u90a3\u4e48\u7b2c\u4e00\u4e2a\u95ee\u9898\u6765\u4e86\uff0cPromise\u662f\u4ec0\u4e48\u73a9\u610f\u5462\uff1f\u662f\u4e00\u4e2a\u7c7b\uff1f\u5bf9\u8c61\uff1f\u6570\u7ec4\uff1f\u51fd\u6570\uff1f<\/p>\n\n\n\n

\u522b\u731c\u4e86\uff0c\u76f4\u63a5\u6253\u5370\u51fa\u6765\u770b\u770b\u5427\uff0cconsole.dir(Promise)\uff0c\u5c31\u8fd9\u4e48\u7b80\u5355\u7c97\u66b4\u3002<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

\u8fd9\u4e48\u4e00\u770b\u5c31\u660e\u767d\u4e86\uff0cPromise\u662f\u4e00\u4e2a\u6784\u9020\u51fd\u6570\uff0c\u81ea\u5df1\u8eab\u4e0a\u6709all\u3001reject\u3001resolve\u8fd9\u51e0\u4e2a\u773c\u719f\u7684\u65b9\u6cd5\uff0c\u539f\u578b\u4e0a\u6709then\u3001catch\u7b49\u540c\u6837\u5f88\u773c\u719f\u7684\u65b9\u6cd5\u3002\u8fd9\u4e48\u8bf4\u7528Promise new\u51fa\u6765\u7684\u5bf9\u8c61\u80af\u5b9a\u5c31\u6709then\u3001catch\u65b9\u6cd5\u55bd\uff0c\u6ca1\u9519\u3002<\/p>\n\n\n\n

\u90a3\u5c31new\u4e00\u4e2a\u73a9\u73a9\u5427\u3002<\/p>\n\n\n\n

var p = new Promise(function(resolve, reject){\n    \/\/\u505a\u4e00\u4e9b\u5f02\u6b65\u64cd\u4f5c\n    setTimeout(function(){\n        console.log('\u6267\u884c\u5b8c\u6210');\n        resolve('\u968f\u4fbf\u4ec0\u4e48\u6570\u636e');\n    }, 2000);\n});<\/pre>\n\n\n\n
Promise\u7684\u6784\u9020\u51fd\u6570\u63a5\u6536\u4e00\u4e2a\u53c2\u6570\uff0c\u662f\u51fd\u6570\uff0c\u5e76\u4e14\u4f20\u5165\u4e24\u4e2a\u53c2\u6570\uff1aresolve\uff0creject\uff0c\u5206\u522b\u8868\u793a\u5f02\u6b65\u64cd\u4f5c\u6267\u884c\u6210\u529f\u540e\u7684\u56de\u8c03\u51fd\u6570\u548c\u5f02\u6b65\u64cd\u4f5c\u6267\u884c\u5931\u8d25\u540e\u7684\u56de\u8c03\u51fd\u6570\u3002\u5176\u5b9e\u8fd9\u91cc\u7528\u201c\u6210\u529f\u201d\u548c\u201c\u5931\u8d25\u201d\u6765\u63cf\u8ff0\u5e76\u4e0d\u51c6\u786e\uff0c\u6309\u7167\u6807\u51c6\u6765\u8bb2\uff0cresolve\u662f\u5c06Promise\u7684\u72b6\u6001\u7f6e\u4e3afullfiled\uff0creject\u662f\u5c06Promise\u7684\u72b6\u6001\u7f6e\u4e3arejected\u3002\u4e0d\u8fc7\u5728\u6211\u4eec\u5f00\u59cb\u9636\u6bb5\u53ef\u4ee5\u5148\u8fd9\u4e48\u7406\u89e3\uff0c\u540e\u9762\u518d\u7ec6\u7a76\u6982\u5ff5\u3002\u00a0\u5728\u4e0a\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u6267\u884c\u4e86\u4e00\u4e2a\u5f02\u6b65\u64cd\u4f5c\uff0c\u4e5f\u5c31\u662fsetTimeout\uff0c2\u79d2\u540e\uff0c\u8f93\u51fa\u201c\u6267\u884c\u5b8c\u6210\u201d\uff0c\u5e76\u4e14\u8c03\u7528resolve\u65b9\u6cd5\u3002<\/p>\n\n\n\n
\u5728\u4e0a\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u6267\u884c\u4e86\u4e00\u4e2a\u5f02\u6b65\u64cd\u4f5c\uff0c\u4e5f\u5c31\u662fsetTimeout\uff0c2\u79d2\u540e\uff0c\u8f93\u51fa\u201c\u6267\u884c\u5b8c\u6210\u201d\uff0c\u5e76\u4e14\u8c03\u7528resolve\u65b9\u6cd5\u3002\u00a0\u8fd0\u884c\u4ee3\u7801\uff0c\u4f1a\u57282\u79d2\u540e\u8f93\u51fa\u201c\u6267\u884c\u5b8c\u6210\u201d\u3002\u6ce8\u610f\uff01\u6211\u53ea\u662fnew\u4e86\u4e00\u4e2a\u5bf9\u8c61\uff0c\u5e76\u6ca1\u6709\u8c03\u7528\u5b83\uff0c\u6211\u4eec\u4f20\u8fdb\u53bb\u7684\u51fd\u6570\u5c31\u5df2\u7ecf\u6267\u884c\u4e86\uff0c\u8fd9\u662f\u9700\u8981\u6ce8\u610f\u7684\u4e00\u4e2a\u7ec6\u8282\u3002\u6240\u4ee5\u6211\u4eec\u7528Promise\u7684\u65f6\u5019\u4e00\u822c\u662f\u5305\u5728\u4e00\u4e2a\u51fd\u6570\u4e2d\uff0c\u5728\u9700\u8981\u7684\u65f6\u5019\u53bb\u8fd0\u884c\u8fd9\u4e2a\u51fd\u6570\uff0c\u5982\uff1a<\/p>\n\n\n\n
function runAsync(){\n    var p = new Promise(function(resolve, reject){\n        \/\/\u505a\u4e00\u4e9b\u5f02\u6b65\u64cd\u4f5c\n        setTimeout(function(){\n            console.log('\u6267\u884c\u5b8c\u6210');\n            resolve('\u968f\u4fbf\u4ec0\u4e48\u6570\u636e');\n        }, 2000);\n    });\n    return p;            \n}\nrunAsync()<\/pre>\n\n\n\n
\u8fd9\u65f6\u5019\u4f60\u5e94\u8be5\u6709\u4e24\u4e2a\u7591\u95ee\uff1a1.\u5305\u88c5\u8fd9\u4e48\u4e00\u4e2a\u51fd\u6570\u6709\u6bdb\u7ebf\u7528\uff1f2.resolve(‘\u968f\u4fbf\u4ec0\u4e48\u6570\u636e’);\u8fd9\u662f\u5e72\u6bdb\u7684\uff1f<\/p>\n\n\n\n
\u6211\u4eec\u7ee7\u7eed\u6765\u8bb2\u3002\u5728\u6211\u4eec\u5305\u88c5\u597d\u7684\u51fd\u6570\u6700\u540e\uff0c\u4f1areturn\u51faPromise\u5bf9\u8c61\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u6267\u884c\u8fd9\u4e2a\u51fd\u6570\u6211\u4eec\u5f97\u5230\u4e86\u4e00\u4e2aPromise\u5bf9\u8c61\u3002\u8fd8\u8bb0\u5f97Promise\u5bf9\u8c61\u4e0a\u6709then\u3001catch\u65b9\u6cd5\u5427\uff1f\u8fd9\u5c31\u662f\u5f3a\u5927\u4e4b\u5904\u4e86\uff0c\u770b\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n\n\n\n
runAsync().then(function(data){\n    console.log(data);\n    \/\/\u540e\u9762\u53ef\u4ee5\u7528\u4f20\u8fc7\u6765\u7684\u6570\u636e\u505a\u4e9b\u5176\u4ed6\u64cd\u4f5c\n    \/\/......\n});<\/pre>\n\n\n\n
\u5728runAsync()\u7684\u8fd4\u56de\u4e0a\u76f4\u63a5\u8c03\u7528then\u65b9\u6cd5\uff0cthen\u63a5\u6536\u4e00\u4e2a\u53c2\u6570\uff0c\u662f\u51fd\u6570\uff0c\u5e76\u4e14\u4f1a\u62ff\u5230\u6211\u4eec\u5728runAsync\u4e2d\u8c03\u7528resolve\u65f6\u4f20\u7684\u7684\u53c2\u6570\u3002\u8fd0\u884c\u8fd9\u6bb5\u4ee3\u7801\uff0c\u4f1a\u57282\u79d2\u540e\u8f93\u51fa\u201c\u6267\u884c\u5b8c\u6210\u201d\uff0c\u7d27\u63a5\u7740\u8f93\u51fa\u201c\u968f\u4fbf\u4ec0\u4e48\u6570\u636e\u201d\u3002<\/p>\n\n\n\n
\u00a0\u8fd9\u65f6\u5019\u4f60\u5e94\u8be5\u6709\u6240\u9886\u609f\u4e86\uff0c\u539f\u6765then\u91cc\u9762\u7684\u51fd\u6570\u5c31\u8ddf\u6211\u4eec\u5e73\u65f6\u7684\u56de\u8c03\u51fd\u6570\u4e00\u4e2a\u610f\u601d\uff0c\u80fd\u591f\u5728runAsync\u8fd9\u4e2a\u5f02\u6b65\u4efb\u52a1\u6267\u884c\u5b8c\u6210\u4e4b\u540e\u88ab\u6267\u884c\u3002\u8fd9\u5c31\u662fPromise\u7684\u4f5c\u7528\u4e86\uff0c\u7b80\u5355\u6765\u8bb2\uff0c\u5c31\u662f\u80fd\u628a\u539f\u6765\u7684\u56de\u8c03\u5199\u6cd5\u5206\u79bb\u51fa\u6765\uff0c\u5728\u5f02\u6b65\u64cd\u4f5c\u6267\u884c\u5b8c\u540e\uff0c\u7528\u94fe\u5f0f\u8c03\u7528\u7684\u65b9\u5f0f\u6267\u884c\u56de\u8c03\u51fd\u6570\u3002<\/p>\n\n\n\n
\u00a0\u4f60\u53ef\u80fd\u4f1a\u4e0d\u5c51\u4e00\u987e\uff0c\u90a3\u4e48\u725b\u903c\u8f70\u8f70\u7684Promise\u5c31\u8fd9\u70b9\u80fd\u8010\uff1f\u6211\u628a\u56de\u8c03\u51fd\u6570\u5c01\u88c5\u4e00\u4e0b\uff0c\u7ed9runAsync\u4f20\u8fdb\u53bb\u4e0d\u4e5f\u4e00\u6837\u5417\uff0c\u5c31\u50cf\u8fd9\u6837\uff1a<\/p>\n\n\n\n
function runAsync(callback){\n    setTimeout(function(){\n        console.log('\u6267\u884c\u5b8c\u6210');\n        callback('\u968f\u4fbf\u4ec0\u4e48\u6570\u636e');\n    }, 2000);\n}\n\nrunAsync(function(data){\n    console.log(data);\n});\n<\/pre>\n\n\n\n
\u6548\u679c\u4e5f\u662f\u4e00\u6837\u7684\uff0c\u8fd8\u8d39\u52b2\u7528Promise\u5e72\u561b\u3002\u90a3\u4e48\u95ee\u9898\u6765\u4e86\uff0c\u6709\u591a\u5c42\u56de\u8c03\u8be5\u600e\u4e48\u529e\uff1f\u5982\u679ccallback\u4e5f\u662f\u4e00\u4e2a\u5f02\u6b65\u64cd\u4f5c\uff0c\u800c\u4e14\u6267\u884c\u5b8c\u540e\u4e5f\u9700\u8981\u6709\u76f8\u5e94\u7684\u56de\u8c03\u51fd\u6570\uff0c\u8be5\u600e\u4e48\u529e\u5462\uff1f\u603b\u4e0d\u80fd\u518d\u5b9a\u4e49\u4e00\u4e2acallback2\uff0c\u7136\u540e\u7ed9callback\u4f20\u8fdb\u53bb\u5427\u3002\u800cPromise\u7684\u4f18\u52bf\u5728\u4e8e\uff0c\u53ef\u4ee5\u5728then\u65b9\u6cd5\u4e2d\u7ee7\u7eed\u5199Promise\u5bf9\u8c61\u5e76\u8fd4\u56de\uff0c\u7136\u540e\u7ee7\u7eed\u8c03\u7528then\u6765\u8fdb\u884c\u56de\u8c03\u64cd\u4f5c\u3002<\/p>\n\n\n\n
\u94fe\u5f0f\u64cd\u4f5c\u7684\u7528\u6cd5<\/strong><\/p>\n\n\n\n
\u6240\u4ee5\uff0c\u4ece\u8868\u9762\u4e0a\u770b\uff0cPromise\u53ea\u662f\u80fd\u591f\u7b80\u5316\u5c42\u5c42\u56de\u8c03\u7684\u5199\u6cd5\uff0c\u800c\u5b9e\u8d28\u4e0a\uff0cPromise\u7684\u7cbe\u9ad3\u662f\u201c\u72b6\u6001\u201d\uff0c\u7528\u7ef4\u62a4\u72b6\u6001\u3001\u4f20\u9012\u72b6\u6001\u7684\u65b9\u5f0f\u6765\u4f7f\u5f97\u56de\u8c03\u51fd\u6570\u80fd\u591f\u53ca\u65f6\u8c03\u7528\uff0c\u5b83\u6bd4\u4f20\u9012callback\u51fd\u6570\u8981\u7b80\u5355\u3001\u7075\u6d3b\u7684\u591a\u3002\u6240\u4ee5\u4f7f\u7528Promise\u7684\u6b63\u786e\u573a\u666f\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n\n\n\n
runAsync1()\n.then(function(data){\n    console.log(data);\n    return runAsync2();\n})\n.then(function(data){\n    console.log(data);\n    return runAsync3();\n})\n.then(function(data){\n    console.log(data);\n});<\/pre>\n\n\n\n
\u8fd9\u6837\u80fd\u591f\u6309\u987a\u5e8f\uff0c\u6bcf\u9694\u4e24\u79d2\u8f93\u51fa\u6bcf\u4e2a\u5f02\u6b65\u56de\u8c03\u4e2d\u7684\u5185\u5bb9\uff0c\u5728runAsync2\u4e2d\u4f20\u7ed9resolve\u7684\u6570\u636e\uff0c\u80fd\u5728\u63a5\u4e0b\u6765\u7684then\u65b9\u6cd5\u4e2d\u62ff\u5230\u3002\u8fd0\u884c\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n
\u731c\u731crunAsync1\u3001runAsync2\u3001runAsync3\u8fd9\u4e09\u4e2a\u51fd\u6570\u90fd\u662f\u5982\u4f55\u5b9a\u4e49\u7684\uff1f\u6ca1\u9519\uff0c\u5c31\u662f\u4e0b\u9762\u8fd9\u6837\uff08\u4ee3\u7801\u8f83\u957f\u8bf7\u81ea\u884c\u5c55\u5f00\uff09\uff1a<\/p>\n\n\n\n
function runAsync1(){\n    var p = new Promise(function(resolve, reject){\n        \/\/\u505a\u4e00\u4e9b\u5f02\u6b65\u64cd\u4f5c\n        setTimeout(function(){\n            console.log('\u5f02\u6b65\u4efb\u52a11\u6267\u884c\u5b8c\u6210');\n            resolve('\u968f\u4fbf\u4ec0\u4e48\u6570\u636e1');\n        }, 1000);\n    });\n    return p;            \n}\nfunction runAsync2(){\n    var p = new Promise(function(resolve, reject){\n        \/\/\u505a\u4e00\u4e9b\u5f02\u6b65\u64cd\u4f5c\n        setTimeout(function(){\n            console.log('\u5f02\u6b65\u4efb\u52a12\u6267\u884c\u5b8c\u6210');\n            resolve('\u968f\u4fbf\u4ec0\u4e48\u6570\u636e2');\n        }, 2000);\n    });\n    return p;            \n}\nfunction runAsync3(){\n    var p = new Promise(function(resolve, reject){\n        \/\/\u505a\u4e00\u4e9b\u5f02\u6b65\u64cd\u4f5c\n        setTimeout(function(){\n            console.log('\u5f02\u6b65\u4efb\u52a13\u6267\u884c\u5b8c\u6210');\n            resolve('\u968f\u4fbf\u4ec0\u4e48\u6570\u636e3');\n        }, 2000);\n    });\n    return p;            \n}<\/pre>\n\n\n\n
\u5728then\u65b9\u6cd5\u4e2d\uff0c\u4f60\u4e5f\u53ef\u4ee5\u76f4\u63a5return\u6570\u636e\u800c\u4e0d\u662fPromise\u5bf9\u8c61\uff0c\u5728\u540e\u9762\u7684then\u4e2d\u5c31\u53ef\u4ee5\u63a5\u6536\u5230\u6570\u636e\u4e86\uff0c\u6bd4\u5982\u6211\u4eec\u628a\u4e0a\u9762\u7684\u4ee3\u7801\u4fee\u6539\u6210\u8fd9\u6837\uff1a<\/p>\n\n\n\n
runAsync1()\n.then(function(data){\n    console.log(data);\n    return runAsync2();\n})\n.then(function(data){\n    console.log(data);\n    return '\u76f4\u63a5\u8fd4\u56de\u6570\u636e';  \/\/\u8fd9\u91cc\u76f4\u63a5\u8fd4\u56de\u6570\u636e\n})\n.then(function(data){\n    console.log(data);\n});<\/pre>\n\n\n\n
\u90a3\u4e48\u8f93\u51fa\u5c31\u53d8\u6210\u4e86\u8fd9\u6837\uff1a<\/p>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n
reject\u7684\u7528\u6cd5<\/strong><\/p>\n\n\n\n
\u5230\u8fd9\u91cc\uff0c\u4f60\u5e94\u8be5\u5bf9\u201cPromise\u662f\u4ec0\u4e48\u73a9\u610f\u201d\u6709\u4e86\u6700\u57fa\u672c\u7684\u4e86\u89e3\u3002\u90a3\u4e48\u6211\u4eec\u63a5\u7740\u6765\u770b\u770bES6\u7684Promise\u8fd8\u6709\u54ea\u4e9b\u529f\u80fd\u3002\u6211\u4eec\u5149\u7528\u4e86resolve\uff0c\u8fd8\u6ca1\u7528reject\u5462\uff0c\u5b83\u662f\u505a\u4ec0\u4e48\u7684\u5462\uff1f\u4e8b\u5b9e\u4e0a\uff0c\u6211\u4eec\u524d\u9762\u7684\u4f8b\u5b50\u90fd\u662f\u53ea\u6709\u201c\u6267\u884c\u6210\u529f\u201d\u7684\u56de\u8c03\uff0c\u8fd8\u6ca1\u6709\u201c\u5931\u8d25\u201d\u7684\u60c5\u51b5\uff0creject\u7684\u4f5c\u7528\u5c31\u662f\u628aPromise\u7684\u72b6\u6001\u7f6e\u4e3arejected\uff0c\u8fd9\u6837\u6211\u4eec\u5728then\u4e2d\u5c31\u80fd\u6355\u6349\u5230\uff0c\u7136\u540e\u6267\u884c\u201c\u5931\u8d25\u201d\u60c5\u51b5\u7684\u56de\u8c03\u3002\u770b\u4e0b\u9762\u7684\u4ee3\u7801\u3002<\/p>\n\n\n\n
function getNumber(){\n    var p = new Promise(function(resolve, reject){\n        \/\/\u505a\u4e00\u4e9b\u5f02\u6b65\u64cd\u4f5c\n        setTimeout(function(){\n            var num = Math.ceil(Math.random()*10); \/\/\u751f\u62101-10\u7684\u968f\u673a\u6570\n            if(num<=5){\n                resolve(num);\n            }\n            else{\n                reject('\u6570\u5b57\u592a\u5927\u4e86');\n            }\n        }, 2000);\n    });\n    return p;            \n}\n\ngetNumber()\n.then(\n    function(data){\n        console.log('resolved');\n        console.log(data);\n    }, \n    function(reason, data){\n        console.log('rejected');\n        console.log(reason);\n    }\n);<\/pre>\n\n\n\n
getNumber\u51fd\u6570\u7528\u6765\u5f02\u6b65\u83b7\u53d6\u4e00\u4e2a\u6570\u5b57\uff0c2\u79d2\u540e\u6267\u884c\u5b8c\u6210\uff0c\u5982\u679c\u6570\u5b57\u5c0f\u4e8e\u7b49\u4e8e5\uff0c\u6211\u4eec\u8ba4\u4e3a\u662f\u201c\u6210\u529f\u201d\u4e86\uff0c\u8c03\u7528resolve\u4fee\u6539Promise\u7684\u72b6\u6001\u3002\u5426\u5219\u6211\u4eec\u8ba4\u4e3a\u662f\u201c\u5931\u8d25\u201d\u4e86\uff0c\u8c03\u7528reject\u5e76\u4f20\u9012\u4e00\u4e2a\u53c2\u6570\uff0c\u4f5c\u4e3a\u5931\u8d25\u7684\u539f\u56e0\u3002\u00a0\u8fd0\u884cgetNumber\u5e76\u4e14\u5728then\u4e2d\u4f20\u4e86\u4e24\u4e2a\u53c2\u6570\uff0cthen\u65b9\u6cd5\u53ef\u4ee5\u63a5\u53d7\u4e24\u4e2a\u53c2\u6570\uff0c\u7b2c\u4e00\u4e2a\u5bf9\u5e94resolve\u7684\u56de\u8c03\uff0c\u7b2c\u4e8c\u4e2a\u5bf9\u5e94reject\u7684\u56de\u8c03\u3002\u6240\u4ee5\u6211\u4eec\u80fd\u591f\u5206\u522b\u62ff\u5230\u4ed6\u4eec\u4f20\u8fc7\u6765\u7684\u6570\u636e\u3002\u591a\u6b21\u8fd0\u884c\u8fd9\u6bb5\u4ee3\u7801\uff0c\u4f60\u4f1a\u968f\u673a\u5f97\u5230\u4e0b\u9762\u4e24\u79cd\u7ed3\u679c\uff1a<\/p>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n
catch\u7684\u7528\u6cd5<\/strong><\/p>\n\n\n\n
\u6211\u4eec\u77e5\u9053Promise\u5bf9\u8c61\u9664\u4e86then\u65b9\u6cd5\uff0c\u8fd8\u6709\u4e00\u4e2acatch\u65b9\u6cd5\uff0c\u5b83\u662f\u505a\u4ec0\u4e48\u7528\u7684\u5462\uff1f\u5176\u5b9e\u5b83\u548cthen\u7684\u7b2c\u4e8c\u4e2a\u53c2\u6570\u4e00\u6837\uff0c\u7528\u6765\u6307\u5b9areject\u7684\u56de\u8c03\uff0c\u7528\u6cd5\u662f\u8fd9\u6837\uff1a<\/p>\n\n\n\n
getNumber()\n.then(function(data){\n    console.log('resolved');\n    console.log(data);\n})\n.catch(function(reason){\n    console.log('rejected');\n    console.log(reason);\n});<\/pre>\n\n\n\n
\u6548\u679c\u548c\u5199\u5728then\u7684\u7b2c\u4e8c\u4e2a\u53c2\u6570\u91cc\u9762\u4e00\u6837\u3002\u4e0d\u8fc7\u5b83\u8fd8\u6709\u53e6\u5916\u4e00\u4e2a\u4f5c\u7528\uff1a\u5728\u6267\u884cresolve\u7684\u56de\u8c03\uff08\u4e5f\u5c31\u662f\u4e0a\u9762then\u4e2d\u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\uff09\u65f6\uff0c\u5982\u679c\u629b\u51fa\u5f02\u5e38\u4e86\uff08\u4ee3\u7801\u51fa\u9519\u4e86\uff09\uff0c\u90a3\u4e48\u5e76\u4e0d\u4f1a\u62a5\u9519\u5361\u6b7bjs\uff0c\u800c\u662f\u4f1a\u8fdb\u5230\u8fd9\u4e2acatch\u65b9\u6cd5\u4e2d\u3002\u8bf7\u770b\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n\n\n\n
getNumber()\n.then(function(data){\n    console.log('resolved');\n    console.log(data);\n    console.log(somedata); \/\/\u6b64\u5904\u7684somedata\u672a\u5b9a\u4e49\n})\n.catch(function(reason){\n    console.log('rejected');\n    console.log(reason);\n});<\/pre>\n\n\n\n
\u5728resolve\u7684\u56de\u8c03\u4e2d\uff0c\u6211\u4eecconsole.log(somedata);\u800csomedata\u8fd9\u4e2a\u53d8\u91cf\u662f\u6ca1\u6709\u88ab\u5b9a\u4e49\u7684\u3002\u5982\u679c\u6211\u4eec\u4e0d\u7528Promise\uff0c\u4ee3\u7801\u8fd0\u884c\u5230\u8fd9\u91cc\u5c31\u76f4\u63a5\u5728\u63a7\u5236\u53f0\u62a5\u9519\u4e86\uff0c\u4e0d\u5f80\u4e0b\u8fd0\u884c\u4e86\u3002\u4f46\u662f\u5728\u8fd9\u91cc\uff0c\u4f1a\u5f97\u5230\u8fd9\u6837\u7684\u7ed3\u679c\uff1a<\/p>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n
\u4e5f\u5c31\u662f\u8bf4\u8fdb\u5230catch\u65b9\u6cd5\u91cc\u9762\u53bb\u4e86\uff0c\u800c\u4e14\u628a\u9519\u8bef\u539f\u56e0\u4f20\u5230\u4e86reason\u53c2\u6570\u4e2d\u3002\u5373\u4fbf\u662f\u6709\u9519\u8bef\u7684\u4ee3\u7801\u4e5f\u4e0d\u4f1a\u62a5\u9519\u4e86\uff0c\u8fd9\u4e0e\u6211\u4eec\u7684try\/catch\u8bed\u53e5\u6709\u76f8\u540c\u7684\u529f\u80fd\u3002<\/p>\n\n\n\n
all\u7684\u7528\u6cd5<\/strong><\/p>\n\n\n\n
Promise\u7684all\u65b9\u6cd5\u63d0\u4f9b\u4e86\u5e76\u884c\u6267\u884c\u5f02\u6b65\u64cd\u4f5c\u7684\u80fd\u529b\uff0c\u5e76\u4e14\u5728\u6240\u6709\u5f02\u6b65\u64cd\u4f5c\u6267\u884c\u5b8c\u540e\u624d\u6267\u884c\u56de\u8c03\u3002\u6211\u4eec\u4ecd\u65e7\u4f7f\u7528\u4e0a\u9762\u5b9a\u4e49\u597d\u7684runAsync1\u3001runAsync2\u3001runAsync3\u8fd9\u4e09\u4e2a\u51fd\u6570\uff0c\u770b\u4e0b\u9762\u7684\u4f8b\u5b50\uff1a<\/p>\n\n\n\n
Promise\n.all([runAsync1(), runAsync2(), runAsync3()])\n.then(function(results){\n    console.log(results);\n});<\/pre>\n\n\n\n
\u7528Promise.all\u6765\u6267\u884c\uff0call\u63a5\u6536\u4e00\u4e2a\u6570\u7ec4\u53c2\u6570\uff0c\u91cc\u9762\u7684\u503c\u6700\u7ec8\u90fd\u7b97\u8fd4\u56dePromise\u5bf9\u8c61\u3002\u8fd9\u6837\uff0c\u4e09\u4e2a\u5f02\u6b65\u64cd\u4f5c\u7684\u5e76\u884c\u6267\u884c\u7684\uff0c\u7b49\u5230\u5b83\u4eec\u90fd\u6267\u884c\u5b8c\u540e\u624d\u4f1a\u8fdb\u5230then\u91cc\u9762\u3002\u90a3\u4e48\uff0c\u4e09\u4e2a\u5f02\u6b65\u64cd\u4f5c\u8fd4\u56de\u7684\u6570\u636e\u54ea\u91cc\u53bb\u4e86\u5462\uff1f\u90fd\u5728then\u91cc\u9762\u5462\uff0call\u4f1a\u628a\u6240\u6709\u5f02\u6b65\u64cd\u4f5c\u7684\u7ed3\u679c\u653e\u8fdb\u4e00\u4e2a\u6570\u7ec4\u4e2d\u4f20\u7ed9then\uff0c\u5c31\u662f\u4e0a\u9762\u7684results\u3002\u6240\u4ee5\u4e0a\u9762\u4ee3\u7801\u7684\u8f93\u51fa\u7ed3\u679c\u5c31\u662f\uff1a<\/p>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n
\u6709\u4e86all\uff0c\u4f60\u5c31\u53ef\u4ee5\u5e76\u884c\u6267\u884c\u591a\u4e2a\u5f02\u6b65\u64cd\u4f5c\uff0c\u5e76\u4e14\u5728\u4e00\u4e2a\u56de\u8c03\u4e2d\u5904\u7406\u6240\u6709\u7684\u8fd4\u56de\u6570\u636e\uff0c\u662f\u4e0d\u662f\u5f88\u9177\uff1f\u6709\u4e00\u4e2a\u573a\u666f\u662f\u5f88\u9002\u5408\u7528\u8fd9\u4e2a\u7684\uff0c\u4e00\u4e9b\u6e38\u620f\u7c7b\u7684\u7d20\u6750\u6bd4\u8f83\u591a\u7684\u5e94\u7528\uff0c\u6253\u5f00\u7f51\u9875\u65f6\uff0c\u9884\u5148\u52a0\u8f7d\u9700\u8981\u7528\u5230\u7684\u5404\u79cd\u8d44\u6e90\u5982\u56fe\u7247\u3001flash\u4ee5\u53ca\u5404\u79cd\u9759\u6001\u6587\u4ef6\u3002\u6240\u6709\u7684\u90fd\u52a0\u8f7d\u5b8c\u540e\uff0c\u6211\u4eec\u518d\u8fdb\u884c\u9875\u9762\u7684\u521d\u59cb\u5316\u3002<\/p>\n\n\n\n
race\u7684\u7528\u6cd5<\/strong><\/p>\n\n\n\n
all\u65b9\u6cd5\u7684\u6548\u679c\u5b9e\u9645\u4e0a\u662f\u300c\u8c01\u8dd1\u7684\u6162\uff0c\u4ee5\u8c01\u4e3a\u51c6\u6267\u884c\u56de\u8c03\u300d\uff0c\u90a3\u4e48\u76f8\u5bf9\u7684\u5c31\u6709\u53e6\u4e00\u4e2a\u65b9\u6cd5\u300c\u8c01\u8dd1\u7684\u5feb\uff0c\u4ee5\u8c01\u4e3a\u51c6\u6267\u884c\u56de\u8c03\u300d\uff0c\u8fd9\u5c31\u662frace\u65b9\u6cd5\uff0c\u8fd9\u4e2a\u8bcd\u672c\u6765\u5c31\u662f\u8d5b\u8dd1\u7684\u610f\u601d\u3002race\u7684\u7528\u6cd5\u4e0eall\u4e00\u6837\uff0c\u6211\u4eec\u628a\u4e0a\u9762runAsync1\u7684\u5ef6\u65f6\u6539\u4e3a1\u79d2\u6765\u770b\u4e00\u4e0b\uff1a<\/p>\n\n\n\n
Promise\n.race([runAsync1(), runAsync2(), runAsync3()])\n.then(function(results){\n    console.log(results);\n});<\/pre>\n\n\n\n
\u8fd9\u4e09\u4e2a\u5f02\u6b65\u64cd\u4f5c\u540c\u6837\u662f\u5e76\u884c\u6267\u884c\u7684\u3002\u7ed3\u679c\u4f60\u5e94\u8be5\u53ef\u4ee5\u731c\u5230\uff0c1\u79d2\u540erunAsync1\u5df2\u7ecf\u6267\u884c\u5b8c\u4e86\uff0c\u6b64\u65f6then\u91cc\u9762\u7684\u5c31\u6267\u884c\u4e86\u3002\u7ed3\u679c\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n
\u4f60\u731c\u5bf9\u4e86\u5417\uff1f\u4e0d\u5b8c\u5168\uff0c\u662f\u5427\u3002\u5728then\u91cc\u9762\u7684\u56de\u8c03\u5f00\u59cb\u6267\u884c\u65f6\uff0crunAsync2()\u548crunAsync3()\u5e76\u6ca1\u6709\u505c\u6b62\uff0c\u4ecd\u65e7\u518d\u6267\u884c\u3002\u4e8e\u662f\u518d\u8fc71\u79d2\u540e\uff0c\u8f93\u51fa\u4e86\u4ed6\u4eec\u7ed3\u675f\u7684\u6807\u5fd7\u3002<\/p>\n\n\n\n
\u8fd9\u4e2arace\u6709\u4ec0\u4e48\u7528\u5462\uff1f\u4f7f\u7528\u573a\u666f\u8fd8\u662f\u5f88\u591a\u7684\uff0c\u6bd4\u5982\u6211\u4eec\u53ef\u4ee5\u7528race\u7ed9\u67d0\u4e2a\u5f02\u6b65\u8bf7\u6c42\u8bbe\u7f6e\u8d85\u65f6\u65f6\u95f4\uff0c\u5e76\u4e14\u5728\u8d85\u65f6\u540e\u6267\u884c\u76f8\u5e94\u7684\u64cd\u4f5c\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n\n\n\n
\/\/\u8bf7\u6c42\u67d0\u4e2a\u56fe\u7247\u8d44\u6e90\nfunction requestImg(){\n    var p = new Promise(function(resolve, reject){\n        var img = new Image();\n        img.onload = function(){\n            resolve(img);\n        }\n        img.src = 'xxxxxx';\n    });\n    return p;\n}\n\n\/\/\u5ef6\u65f6\u51fd\u6570\uff0c\u7528\u4e8e\u7ed9\u8bf7\u6c42\u8ba1\u65f6\nfunction timeout(){\n    var p = new Promise(function(resolve, reject){\n        setTimeout(function(){\n            reject('\u56fe\u7247\u8bf7\u6c42\u8d85\u65f6');\n        }, 5000);\n    });\n    return p;\n}\n\nPromise\n.race([requestImg(), timeout()])\n.then(function(results){\n    console.log(results);\n})\n.catch(function(reason){\n    console.log(reason);\n});<\/pre>\n\n\n\n
requestImg\u51fd\u6570\u4f1a\u5f02\u6b65\u8bf7\u6c42\u4e00\u5f20\u56fe\u7247\uff0c\u6211\u628a\u5730\u5740\u5199\u4e3a”xxxxxx”\uff0c\u6240\u4ee5\u80af\u5b9a\u662f\u65e0\u6cd5\u6210\u529f\u8bf7\u6c42\u5230\u7684\u3002timeout\u51fd\u6570\u662f\u4e00\u4e2a\u5ef6\u65f65\u79d2\u7684\u5f02\u6b65\u64cd\u4f5c\u3002\u6211\u4eec\u628a\u8fd9\u4e24\u4e2a\u8fd4\u56dePromise\u5bf9\u8c61\u7684\u51fd\u6570\u653e\u8fdbrace\uff0c\u4e8e\u662f\u4ed6\u4fe9\u5c31\u4f1a\u8d5b\u8dd1\uff0c\u5982\u679c5\u79d2\u4e4b\u5185\u56fe\u7247\u8bf7\u6c42\u6210\u529f\u4e86\uff0c\u90a3\u4e48\u904d\u8fdb\u5165then\u65b9\u6cd5\uff0c\u6267\u884c\u6b63\u5e38\u7684\u6d41\u7a0b\u3002\u5982\u679c5\u79d2\u949f\u56fe\u7247\u8fd8\u672a\u6210\u529f\u8fd4\u56de\uff0c\u90a3\u4e48timeout\u5c31\u8dd1\u8d62\u4e86\uff0c\u5219\u8fdb\u5165catch\uff0c\u62a5\u51fa\u201c\u56fe\u7247\u8bf7\u6c42\u8d85\u65f6\u201d\u7684\u4fe1\u606f\u3002\u8fd0\u884c\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n
\u603b\u7ed3<\/strong><\/p>\n\n\n\n
ES6 Promise\u7684\u5185\u5bb9\u5c31\u8fd9\u4e9b\u5417\uff1f\u662f\u7684\uff0c\u80fd\u7528\u5230\u7684\u57fa\u672c\u5c31\u8fd9\u4e9b\u3002\u6211\u600e\u4e48\u8fd8\u89c1\u8fc7done\u3001finally\u3001success\u3001fail\u7b49\uff0c\u8fd9\u4e9b\u662f\u5565\uff1f\u8fd9\u4e9b\u5e76\u4e0d\u5728Promise\u6807\u51c6\u4e2d\uff0c\u800c\u662f\u6211\u4eec\u81ea\u5df1\u5b9e\u73b0\u7684\u8bed\u6cd5\u7cd6\u3002\u00a0<\/p>\n\n\n\n
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