(window.webpackJsonp=window.webpackJsonp||[]).push([[136],{466:function(s,t,a){"use strict";a.r(t);var n=a(3),e=Object(n.a)({},(function(){var s=this,t=s._self._c;return t("ContentSlotsDistributor",{attrs:{"slot-key":s.$parent.slotKey}},[t("blockquote",[t("p",[s._v("说明：本章内容为博主在原教程基础上添加自己的学习笔记，来源"),t("a",{attrs:{href:"https://wangdoc.com/javascript/",target:"_blank",rel:"noopener noreferrer"}},[s._v("https://wangdoc.com/javascript/"),t("OutboundLink")],1),s._v("，教程版权归原作者所有。")])]),s._v(" "),t("h1",{attrs:{id:"基础篇"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#基础篇"}},[s._v("#")]),s._v(" 基础篇")]),s._v(" "),t("h2",{attrs:{id:"一、js的一些名词概念"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#一、js的一些名词概念"}},[s._v("#")]),s._v(" 一、JS的一些名词概念")]),s._v(" "),t("h4",{attrs:{id:"什么是作用域"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#什么是作用域"}},[s._v("#")]),s._v(" 什么是作用域？")]),s._v(" "),t("p",[s._v("变量存在的范围。")]),s._v(" "),t("p",[s._v("可分为全局作用域和函数作用域，ES6新增块级作用域。")]),s._v(" 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"),t("ul",[t("li",[t("strong",[s._v("message")]),s._v("：错误提示信息")]),s._v(" "),t("li",[t("strong",[s._v("name")]),s._v("：错误名称（非标准属性）")]),s._v(" "),t("li",[t("strong",[s._v("stack")]),s._v("：错误的堆栈（非标准属性）")])]),s._v(" "),t("p",[s._v("使用"),t("code",[s._v("name")]),s._v("和"),t("code",[s._v("message")]),s._v("这两个属性，可以对发生什么错误有一个大概的了解。")]),s._v(" "),t("div",{staticClass:"language-js line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-js"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("var")]),s._v(" err "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("new")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token class-name"}},[s._v("Error")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'出错了'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token 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Error")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("//    at throwit (~/examples/throwcatch.js:9:11) // 堆栈的最内层throwit函数")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("//    at catchit (~/examples/throwcatch.js:3:9) // 向外一层catchit函数")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("//    at repl:1:5 // 函数的运行环境")]),s._v("\n\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 堆栈信息说明")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// Error 错误")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("//    at throwit 在throwit方法 (~/examples/throwcatch.js:9:11) 文件名：第几行：第几个字符")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("//    at catchit 在catchit方法 (~/examples/throwcatch.js:3:9) 文件名：第几行：第几个字符")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("//    at repl:1:5 // 函数的运行环境")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br"),t("span",{staticClass:"line-number"},[s._v("10")]),t("br"),t("span",{staticClass:"line-number"},[s._v("11")]),t("br"),t("span",{staticClass:"line-number"},[s._v("12")]),t("br"),t("span",{staticClass:"line-number"},[s._v("13")]),t("br"),t("span",{staticClass:"line-number"},[s._v("14")]),t("br"),t("span",{staticClass:"line-number"},[s._v("15")]),t("br"),t("span",{staticClass:"line-number"},[s._v("16")]),t("br"),t("span",{staticClass:"line-number"},[s._v("17")]),t("br"),t("span",{staticClass:"line-number"},[s._v("18")]),t("br"),t("span",{staticClass:"line-number"},[s._v("19")]),t("br"),t("span",{staticClass:"line-number"},[s._v("20")]),t("br"),t("span",{staticClass:"line-number"},[s._v("21")]),t("br"),t("span",{staticClass:"line-number"},[s._v("22")]),t("br"),t("span",{staticClass:"line-number"},[s._v("23")]),t("br"),t("span",{staticClass:"line-number"},[s._v("24")]),t("br")])]),t("p",[s._v("上面代码中，错误堆栈的最内层是"),t("code",[s._v("throwit")]),s._v("函数，然后是"),t("code",[s._v("catchit")]),s._v("函数，最后是函数的运行环境。")]),s._v(" "),t("h3",{attrs:{id:"_2、原生错误类型"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#_2、原生错误类型"}},[s._v("#")]),s._v(" 2、原生错误类型")]),s._v(" "),t("p",[t("code",[s._v("Error")]),s._v("实例对象是最一般的错误类型，在它的基础上，JavaScript 还定义了其他6种错误对象。也就是说，存在"),t("code",[s._v("Error")]),s._v("的6个派生对象。")]),s._v(" "),t("h4",{attrs:{id:"syntaxerror-对象-语法错误"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#syntaxerror-对象-语法错误"}},[s._v("#")]),s._v(" SyntaxError 对象（语法错误）")]),s._v(" "),t("p",[t("code",[s._v("SyntaxError")]),s._v("对象是解析代码时发生的"),t("strong",[s._v("语法错误")]),s._v("。")]),s._v(" "),t("div",{staticClass:"language-js line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-js"}},[t("code",[t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 变量名错误")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("var")]),s._v(" 1a"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// Uncaught SyntaxError: Invalid or unexpected token")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 语法错误：无效或意外的标记符号")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 缺少括号")]),s._v("\nconsole"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),s._v("log "),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'hello'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// Uncaught SyntaxError: Unexpected string")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 语法错误：意外的字符串")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br")])]),t("p",[s._v("上面代码的错误，都是在语法解析阶段就可以发现，所以会抛出"),t("code",[s._v("SyntaxError")]),s._v("。第一个错误提示是“token 非法”，第二个错误提示是“字符串不符合要求”。")]),s._v(" "),t("h4",{attrs:{id:"referenceerror-对象-引用错误"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#referenceerror-对象-引用错误"}},[s._v("#")]),s._v(" ReferenceError 对象（引用错误）")]),s._v(" "),t("p",[t("code",[s._v("ReferenceError")]),s._v("对象是"),t("strong",[s._v("引用一个不存在的变量时发生的错误")]),s._v("。")]),s._v(" "),t("div",{staticClass:"language-js line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-js"}},[t("code",[t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 使用一个不存在的变量")]),s._v("\nunknownVariable\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// Uncaught ReferenceError: unknownVariable is not defined")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 引用错误： unknownVariable 没有定义")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br")])]),t("p",[s._v("另一种触发场景是，将一个值分配给无法分配的对象，比如对函数的运行结果或者"),t("code",[s._v("this")]),s._v("赋值。")]),s._v(" "),t("div",{staticClass:"language-js line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-js"}},[t("code",[t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 等号左侧不是变量")]),s._v("\nconsole"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("log")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token number"}},[s._v("1")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// Uncaught ReferenceError: Invalid left-hand side in assignment")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 引用错误： 赋值中左边是无效的")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// this 对象不能手动赋值")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("this")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token number"}},[s._v("1")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// ReferenceError: Invalid left-hand side in assignment")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 引用错误：  赋值中左边是无效的")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br")])]),t("p",[s._v("上面代码对函数"),t("code",[s._v("console.log")]),s._v("的运行结果和"),t("code",[s._v("this")]),s._v("赋值，结果都引发了"),t("code",[s._v("ReferenceError")]),s._v("错误。")]),s._v(" "),t("h4",{attrs:{id:"rangeerror-对象-范围错误"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#rangeerror-对象-范围错误"}},[s._v("#")]),s._v(" RangeError 对象（范围错误）")]),s._v(" 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"),t("h2",{attrs:{id:"四、console对象"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#四、console对象"}},[s._v("#")]),s._v(" 四、console对象")]),s._v(" "),t("h3",{attrs:{id:"console-time-console-timeend-用于计算程序的用时"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#console-time-console-timeend-用于计算程序的用时"}},[s._v("#")]),s._v(" console.time()，console.timeEnd() （用于计算程序的用时）")]),s._v(" "),t("p",[s._v("这两个方法用于计时，可以算出一个操作所花费的准确时间。")]),s._v(" "),t("div",{staticClass:"language- line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-text"}},[t("code",[s._v("console.time('Array initialize');\n\nvar array= new Array(1000000);\nfor (var i = array.length - 1; i >= 0; i--) {\n  array[i] = new Object();\n};\n\nconsole.timeEnd('Array initialize');\n// Array initialize: 1914.481ms\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br")])]),t("p",[t("code",[s._v("time")]),s._v("方法表示计时开始，"),t("code",[s._v("timeEnd")]),s._v("方法表示计时结束。它们的参数是计时器的名称。调用"),t("code",[s._v("timeEnd")]),s._v("方法之后，控制台会显示“计时器名称: 所耗费的时间”。")]),s._v(" "),t("h2",{attrs:{id:"文档"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#文档"}},[s._v("#")]),s._v(" 文档")]),s._v(" "),t("p",[s._v("学习文档："),t("a",{attrs:{href:"https://wangdoc.com/javascript/",target:"_blank",rel:"noopener noreferrer"}},[s._v("https://wangdoc.com/javascript/"),t("OutboundLink")],1)])])}),[],!1,null,null,null);t.default=e.exports}}]);