text: (window.webpackJsonp=window.webpackJsonp||[]).push([[80],{153:function(t,s,a){"use strict";a.r(s);var n=a(0),e=Object(n.a)({},(function(){var t=this,s=t.$createElement,a=t._self._c||s;return a("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[a("h1",{attrs:{id:"readonly"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#readonly"}},[t._v("#")]),t._v(" readonly")]),t._v(" "),a("p",[t._v("TypeScript 类型系统允许你在一个接口里使用 "),a("code",[t._v("readonly")]),t._v(" 来标记属性。它能让你以一种更安全的方式工作（不可预期的改变是很糟糕的）：")]),t._v(" "),a("div",{staticClass:"language-ts extra-class"},[a("pre",{pre:!0,attrs:{class:"language-ts"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("function")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("foo")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token parameter"}},[t._v("config"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(":")]),t._v(" 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"),a("span",{pre:!0,attrs:{class:"token builtin"}},[t._v("number")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("interface")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("State")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("readonly")]),t._v(" bar"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(":")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token builtin"}},[t._v("number")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("export")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" 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