{"id":58,"date":"2022-05-29T12:15:53","date_gmt":"2022-05-29T04:15:53","guid":{"rendered":"http:\/\/www.33weixin.com\/index\/?p=58"},"modified":"2022-05-29T12:16:51","modified_gmt":"2022-05-29T04:16:51","slug":"%e6%b7%b1%e5%85%a5%e5%93%8d%e5%ba%94%e5%bc%8f%e5%8e%9f%e7%90%86","status":"publish","type":"post","link":"http:\/\/www.33weixin.com\/index\/index.php\/2022\/05\/29\/%e6%b7%b1%e5%85%a5%e5%93%8d%e5%ba%94%e5%bc%8f%e5%8e%9f%e7%90%86\/","title":{"rendered":"\u6df1\u5165\u54cd\u5e94\u5f0f\u539f\u7406"},"content":{"rendered":"

\u6211\u4eec\u5df2\u7ecf\u6db5\u76d6\u4e86\u5927\u90e8\u5206\u7684\u57fa\u7840\u77e5\u8bc6 – \u73b0\u5728\u662f\u65f6\u5019\u6df1\u5165\u5e95\u5c42\u539f\u7406\u4e86\uff01Vue \u6700\u663e\u8457\u7684\u7279\u6027\u4e4b\u4e00\u4fbf\u662f\u4e0d\u592a\u5f15\u4eba\u6ce8\u610f\u7684\u54cd\u5e94\u5f0f\u7cfb\u7edf(reactivity system)\u3002\u6a21\u578b\u5c42(model)\u53ea\u662f\u666e\u901a JavaScript \u5bf9\u8c61\uff0c\u4fee\u6539\u5b83\u5219\u66f4\u65b0\u89c6\u56fe(view)\u3002\u8fd9\u4f1a\u8ba9\u72b6\u6001\u7ba1\u7406\u53d8\u5f97\u975e\u5e38\u7b80\u5355\u4e14\u76f4\u89c2\uff0c\u4e0d\u8fc7\u7406\u89e3\u5b83\u7684\u5de5\u4f5c\u539f\u7406\u4ee5\u907f\u514d\u4e00\u4e9b\u5e38\u89c1\u7684\u95ee\u9898\u4e5f\u662f\u5f88\u91cd\u8981\u7684\u3002\u5728\u672c\u8282\u4e2d\uff0c\u6211\u4eec\u5c06\u5f00\u59cb\u6df1\u5165\u6316\u6398 Vue \u54cd\u5e94\u5f0f\u7cfb\u7edf\u7684\u5e95\u5c42\u7ec6\u8282\u3002<\/p>\n

\u5982\u4f55\u8ffd\u8e2a\u53d8\u5316<\/h2>\n

\u628a\u4e00\u4e2a\u666e\u901a Javascript \u5bf9\u8c61\u4f20\u7ed9 Vue \u5b9e\u4f8b\u7684\u00a0data<\/code>\u00a0\u9009\u9879\uff0cVue \u5c06\u904d\u5386\u6b64\u5bf9\u8c61\u6240\u6709\u7684\u5c5e\u6027\uff0c\u5e76\u4f7f\u7528\u00a0Object.defineProperty<\/a>\u00a0\u628a\u8fd9\u4e9b\u5c5e\u6027\u5168\u90e8\u8f6c\u4e3a getter\/setter\u3002Object.defineProperty \u662f\u4ec5 ES5 \u652f\u6301\uff0c\u4e14\u65e0\u6cd5 shim \u7684\u7279\u6027\uff0c\u8fd9\u4e5f\u5c31\u662f\u4e3a\u4ec0\u4e48 Vue \u4e0d\u652f\u6301 IE8 \u4ee5\u53ca\u66f4\u4f4e\u7248\u672c\u6d4f\u89c8\u5668\u7684\u539f\u56e0\u3002<\/p>\n

getter\/setter \u5bf9\u4e8e\u7528\u6237\u6765\u8bf4\u662f\u4e0d\u53ef\u89c1\u7684\uff0c\u4f46\u662f\u57fa\u4e8e\u6b64\u5185\u90e8\u673a\u5236\uff0c\u53ef\u4ee5\u4f7f Vue \u5728\u5c5e\u6027\u88ab\u8bbf\u95ee\u548c\u4fee\u6539\u65f6\u53bb\u89e6\u53d1\u76f8\u5e94\u7684 getter \u548c setter\uff0c\u4ee5\u5b9e\u73b0\u4f9d\u8d56\u8ffd\u8e2a(dependency-track)\u548c\u53d8\u66f4\u901a\u77e5(change-notification)\u3002\u8fd9\u91cc\u9700\u8981\u6ce8\u610f\u7684\u95ee\u9898\u662f\uff0c\u6d4f\u89c8\u5668\u63a7\u5236\u53f0\u5728\u8bb0\u5f55\u5df2\u8f6c\u5316\u4e3a getter\/setter \u683c\u5f0f\u7684\u6570\u636e\u5bf9\u8c61\u65f6\uff0c\u4f1a\u548c\u5e38\u89c1\u7684\u666e\u901a\u6570\u636e\u5bf9\u8c61\u7684\u683c\u5f0f\u4e0d\u540c\uff0c\u6240\u4ee5\u4e3a\u4e86\u83b7\u53d6\u66f4\u52a0\u53cb\u597d\u7684\u67e5\u770b\u754c\u9762\uff0c\u4f60\u53ef\u80fd\u9700\u8981\u5b89\u88c5\u00a0vue-devtools<\/a>\u3002<\/p>\n

\u6bcf\u4e2a\u7ec4\u4ef6\u5b9e\u4f8b\u90fd\u6709\u76f8\u5e94\u7684\u00a0watcher<\/strong>\u00a0\u5b9e\u4f8b\u5bf9\u8c61\uff0c\u5b83\u4f1a\u5728\u7ec4\u4ef6\u6e32\u67d3\u7684\u8fc7\u7a0b\u4e2d\u628a\u5c5e\u6027\u8bb0\u5f55\u4e3a\u4f9d\u8d56\uff0c\u4e4b\u540e\u5f53\u4f9d\u8d56\u9879\u7684\u00a0setter<\/code>\u00a0\u88ab\u8c03\u7528\u65f6\uff0c\u4f1a\u901a\u77e5\u00a0watcher<\/code>\u00a0\u91cd\u65b0\u8ba1\u7b97\uff0c\u4ece\u800c\u81f4\u4f7f\u5b83\u5173\u8054\u7684\u7ec4\u4ef6\u5f97\u4ee5\u66f4\u65b0\u3002<\/p>\n

\"data\"<\/p>\n

\u53d8\u5316\u68c0\u6d4b\u95ee\u9898<\/h2>\n

\u53d7\u73b0\u4ee3 Javascript \u7684\u9650\u5236\uff08\u4ee5\u53ca\u5e9f\u5f03\u00a0Object.observe<\/code>\uff09\uff0cVue\u00a0\u4e0d\u80fd\u68c0\u6d4b\u5230\u5bf9\u8c61\u5c5e\u6027\u7684\u6dfb\u52a0\u6216\u5220\u9664<\/strong>\u3002\u7531\u4e8e Vue \u4f1a\u5728\u521d\u59cb\u5316\u5b9e\u4f8b\u65f6\u5bf9\u5c5e\u6027\u6267\u884c\u00a0getter\/setter<\/code>\u00a0\u8f6c\u5316\u8fc7\u7a0b\uff0c\u6240\u4ee5\u5c5e\u6027\u5fc5\u987b\u5728\u00a0data<\/code>\u00a0\u5bf9\u8c61\u4e0a\u5b58\u5728\u624d\u80fd\u8ba9 Vue \u8f6c\u6362\u5b83\uff0c\u8fd9\u6837\u624d\u80fd\u8ba9\u5b83\u662f\u54cd\u5e94\u7684\u3002\u4f8b\u5982\uff1a<\/p>\n

var<\/span> vm = new<\/span> Vue({\n  data:{\n  a:1<\/span>\n  }\n})\n\n\/\/ `vm.a` \u662f\u54cd\u5e94\u7684<\/span>\n\nvm.b = 2<\/span>\n\/\/ `vm.b` \u662f\u975e\u54cd\u5e94\u7684<\/span>\n<\/code><\/pre>\n
Vue \u4e0d\u5141\u8bb8\u5728\u5df2\u7ecf\u521b\u5efa\u7684\u5b9e\u4f8b\u4e0a\u52a8\u6001\u6dfb\u52a0\u65b0\u7684\u6839\u7ea7\u54cd\u5e94\u5f0f\u5c5e\u6027(root-level reactive property)\u3002\u7136\u800c\u5b83\u53ef\u4ee5\u4f7f\u7528\u00a0Vue.set(object, key, value)<\/code>\u00a0\u65b9\u6cd5\u5c06\u54cd\u5e94\u5c5e\u6027\u6dfb\u52a0\u5230\u5d4c\u5957\u7684\u5bf9\u8c61\u4e0a\uff1a<\/p>\n
Vue.set(vm.someObject, 'b'<\/span>, 2<\/span>)\n<\/code><\/pre>\n
\u60a8\u8fd8\u53ef\u4ee5\u4f7f\u7528\u00a0vm.$set<\/code>\u00a0\u5b9e\u4f8b\u65b9\u6cd5\uff0c\u8fd9\u4e5f\u662f\u5168\u5c40\u00a0Vue.set<\/code>\u00a0\u65b9\u6cd5\u7684\u522b\u540d\uff1a<\/p>\n
this<\/span>.$set(this<\/span>.someObject,'b'<\/span>,2<\/span>)\n<\/code><\/pre>\n
\u6709\u65f6\u4f60\u60f3\u5411\u5df2\u6709\u5bf9\u8c61\u4e0a\u6dfb\u52a0\u4e00\u4e9b\u5c5e\u6027\uff0c\u4f8b\u5982\u4f7f\u7528\u00a0Object.assign()<\/code>\u00a0\u6216\u00a0_.extend()<\/code>\u00a0\u65b9\u6cd5\u6765\u6dfb\u52a0\u5c5e\u6027\u3002\u4f46\u662f\uff0c\u6dfb\u52a0\u5230\u5bf9\u8c61\u4e0a\u7684\u65b0\u5c5e\u6027\u4e0d\u4f1a\u89e6\u53d1\u66f4\u65b0\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\u53ef\u4ee5\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\uff0c\u8ba9\u5b83\u5305\u542b\u539f\u5bf9\u8c61\u7684\u5c5e\u6027\u548c\u65b0\u7684\u5c5e\u6027\uff1a<\/p>\n
\/\/ \u4ee3\u66ff `Object.assign(this.someObject, { a: 1, b: 2 })`<\/span>\nthis<\/span>.someObject = Object<\/span>.assign({}, this<\/span>.someObject, { a: 1<\/span>, b: 2<\/span> })\n<\/code><\/pre>\n
\u58f0\u660e\u54cd\u5e94\u5f0f\u5c5e\u6027<\/h2>\n
\u7531\u4e8e Vue \u4e0d\u5141\u8bb8\u52a8\u6001\u6dfb\u52a0\u6839\u7ea7\u54cd\u5e94\u5f0f\u5c5e\u6027\uff0c\u6240\u4ee5\u4f60\u5fc5\u987b\u5728\u521d\u59cb\u5316\u5b9e\u4f8b\u524d\u58f0\u660e\u6839\u7ea7\u54cd\u5e94\u5f0f\u5c5e\u6027\uff0c\u54ea\u6015\u53ea\u662f\u4e00\u4e2a\u7a7a\u503c:<\/p>\n
var<\/span> vm = new<\/span> Vue({\n  data: {\n    \/\/ \u58f0\u660e message \u4e3a\u4e00\u4e2a\u7a7a\u503c\u5b57\u7b26\u4e32<\/span>\n    message: ''<\/span>\n  },\n  template: '<div>{{ message }}<\/div>'<\/span>\n})\n\/\/ \u4e4b\u540e\u8bbe\u7f6e `message` <\/span>\nvm.message = 'Hello!'<\/span>\n<\/code><\/pre>\n
\u5982\u679c\u4f60\u5728 data \u9009\u9879\u4e2d\u672a\u58f0\u660e\u00a0message<\/code>\uff0cVue \u5c06\u8b66\u544a\u4f60\u6e32\u67d3\u51fd\u6570\u5728\u8bd5\u56fe\u8bbf\u95ee\u7684\u5c5e\u6027\u4e0d\u5b58\u5728\u3002<\/p>\n
\u8fd9\u6837\u7684\u9650\u5236\u5728\u80cc\u540e\u662f\u6709\u5176\u6280\u672f\u539f\u56e0\u7684\uff0c\u5b83\u6d88\u9664\u4e86\u5728\u4f9d\u8d56\u9879\u8ddf\u8e2a\u7cfb\u7edf\u4e2d\u7684\u4e00\u7c7b\u8fb9\u754c\u60c5\u51b5\uff0c\u4e5f\u4f7f Vue \u5b9e\u4f8b\u5728\u7c7b\u578b\u68c0\u67e5\u7cfb\u7edf\u7684\u5e2e\u52a9\u4e0b\u8fd0\u884c\u7684\u66f4\u9ad8\u6548\u3002\u800c\u4e14\u5728\u4ee3\u7801\u53ef\u7ef4\u62a4\u6027\u65b9\u9762\u4e5f\u6709\u4e00\u70b9\u91cd\u8981\u7684\u8003\u8651\uff1adata<\/code>\u00a0\u5bf9\u8c61\u5c31\u50cf\u7ec4\u4ef6\u72b6\u6001\u7684\u6982\u8981\uff0c\u63d0\u524d\u58f0\u660e\u6240\u6709\u7684\u54cd\u5e94\u5f0f\u5c5e\u6027\uff0c\u53ef\u4ee5\u8ba9\u7ec4\u4ef6\u4ee3\u7801\u5728\u4ee5\u540e\u91cd\u65b0\u9605\u8bfb\u6216\u5176\u4ed6\u5f00\u53d1\u4eba\u5458\u9605\u8bfb\u65f6\u66f4\u6613\u4e8e\u88ab\u7406\u89e3\u3002<\/p>\n
\u5f02\u6b65\u66f4\u65b0\u961f\u5217<\/h2>\n
\u53ef\u80fd\u4f60\u8fd8\u6ca1\u6709\u6ce8\u610f\u5230\uff0cVue\u00a0\u5f02\u6b65<\/strong>\u6267\u884c DOM \u66f4\u65b0\u3002\u53ea\u8981\u89c2\u5bdf\u5230\u6570\u636e\u53d8\u5316\uff0cVue \u5c06\u5f00\u542f\u4e00\u4e2a\u961f\u5217\uff0c\u5e76\u7f13\u51b2\u5728\u540c\u4e00\u4e8b\u4ef6\u5faa\u73af\u4e2d\u53d1\u751f\u7684\u6240\u6709\u6570\u636e\u6539\u53d8\u3002\u5982\u679c\u540c\u4e00\u4e2a watcher \u88ab\u591a\u6b21\u89e6\u53d1\uff0c\u53ea\u4f1a\u4e00\u6b21\u63a8\u5165\u5230\u961f\u5217\u4e2d\u3002\u8fd9\u79cd\u5728\u7f13\u51b2\u65f6\u53bb\u9664\u91cd\u590d\u6570\u636e\u5bf9\u4e8e\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u8ba1\u7b97\u548c DOM \u64cd\u4f5c\u4e0a\u975e\u5e38\u91cd\u8981\u3002\u7136\u540e\uff0c\u5728\u4e0b\u4e00\u4e2a\u7684\u4e8b\u4ef6\u5faa\u73af\u201ctick\u201d\u4e2d\uff0cVue \u5237\u65b0\u961f\u5217\u5e76\u6267\u884c\u5b9e\u9645\uff08\u5df2\u53bb\u91cd\u7684\uff09\u5de5\u4f5c\u3002Vue \u5728\u5185\u90e8\u5c1d\u8bd5\u5bf9\u5f02\u6b65\u961f\u5217\u4f7f\u7528\u539f\u751f\u7684\u00a0Promise.then<\/code>\u00a0\u548c\u00a0MutationObserver<\/code>\uff0c\u5982\u679c\u6267\u884c\u73af\u5883\u4e0d\u652f\u6301\uff0c\u4f1a\u91c7\u7528\u00a0setTimeout(fn, 0)<\/code>\u00a0\u4ee3\u66ff\u3002<\/p>\n
\u4f8b\u5982\uff0c\u5f53\u4f60\u8bbe\u7f6e\u00a0vm.someData = 'new value'<\/code>\u00a0\uff0c\u8be5\u7ec4\u4ef6\u4e0d\u4f1a\u7acb\u5373\u91cd\u65b0\u6e32\u67d3\u3002\u5f53\u5237\u65b0\u961f\u5217\u65f6\uff0c\u7ec4\u4ef6\u4f1a\u5728\u4e8b\u4ef6\u5faa\u73af\u961f\u5217\u6e05\u7a7a\u65f6\u7684\u4e0b\u4e00\u4e2a\u201ctick\u201d\u66f4\u65b0\u3002\u591a\u6570\u60c5\u51b5\u6211\u4eec\u4e0d\u9700\u8981\u5173\u5fc3\u8fd9\u4e2a\u8fc7\u7a0b\uff0c\u4f46\u662f\u5982\u679c\u4f60\u60f3\u5728 DOM \u72b6\u6001\u66f4\u65b0\u540e\u505a\u70b9\u4ec0\u4e48\uff0c\u8fd9\u5c31\u53ef\u80fd\u4f1a\u6709\u4e9b\u68d8\u624b\u3002\u867d\u7136 Vue.js \u901a\u5e38\u9f13\u52b1\u5f00\u53d1\u4eba\u5458\u6cbf\u7740\u201c\u6570\u636e\u9a71\u52a8\u201d\u7684\u65b9\u5f0f\u601d\u8003\uff0c\u907f\u514d\u76f4\u63a5\u63a5\u89e6 DOM\uff0c\u4f46\u662f\u6709\u65f6\u6211\u4eec\u786e\u5b9e\u8981\u8fd9\u4e48\u505a\u3002\u4e3a\u4e86\u5728\u6570\u636e\u53d8\u5316\u4e4b\u540e\u7b49\u5f85 Vue \u5b8c\u6210\u66f4\u65b0 DOM \uff0c\u53ef\u4ee5\u5728\u6570\u636e\u53d8\u5316\u4e4b\u540e\u7acb\u5373\u4f7f\u7528\u00a0Vue.nextTick(callback)<\/code>\u00a0\u3002\u8fd9\u6837\u56de\u8c03\u51fd\u6570\u5728 DOM \u66f4\u65b0\u5b8c\u6210\u540e\u5c31\u4f1a\u8c03\u7528\u3002\u4f8b\u5982\uff1a<\/p>\n
<div<\/span> id<\/span>=\"example\"<\/span>><\/span>{{message}}<\/div<\/span>><\/span>\n<\/code><\/pre>\n
var<\/span> vm = new<\/span> Vue({\n  el: '#example'<\/span>,\n  data: {\n    message: '123'<\/span>\n  }\n})\nvm.message = 'new message'<\/span> \/\/ \u66f4\u6539\u6570\u636e<\/span>\nvm.$el.textContent === 'new message'<\/span> \/\/ false<\/span>\nVue.nextTick(function<\/span> () <\/span>{\n  vm.$el.textContent === 'new message'<\/span> \/\/ true<\/span>\n})\n<\/code><\/pre>\n
\u5728\u7ec4\u4ef6\u5185\u4f7f\u7528\u00a0vm.$nextTick()<\/code>\u00a0\u5b9e\u4f8b\u65b9\u6cd5\u7279\u522b\u65b9\u4fbf\uff0c\u56e0\u4e3a\u5b83\u4e0d\u9700\u8981\u5168\u5c40\u00a0Vue<\/code>\u00a0\uff0c\u5e76\u4e14\u56de\u8c03\u51fd\u6570\u4e2d\u7684\u00a0this<\/code>\u00a0\u5c06\u81ea\u52a8\u7ed1\u5b9a\u5230\u5f53\u524d\u7684 Vue \u5b9e\u4f8b\u4e0a\uff1a<\/p>\n
Vue.component('example'<\/span>, {\n  template: '<span>{{ message }}<\/span>'<\/span>,\n  data: function<\/span> () <\/span>{\n    return<\/span> {\n      message: 'not updated'<\/span>\n    }\n  },\n  methods: {\n    updateMessage: function<\/span> () <\/span>{\n      this<\/span>.message = 'updated'<\/span>\n      console<\/span>.log(this<\/span>.$el.textContent) \/\/ => '\u6ca1\u6709\u66f4\u65b0'<\/span>\n      this<\/span>.$nextTick(function<\/span> () <\/span>{\n        console<\/span>.log(this<\/span>.$el.textContent) \/\/ => '\u66f4\u65b0\u5b8c\u6210'<\/span>\n      })\n    }\n  }\n})<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
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