我注意到在Internet Explorer中（但不幸的是，在我测试的其他浏览器中没有），您可以使用一些Unicode变量名称。这让我很开心，我非常高兴我可以像这样编写有趣的 Unicode 代码：

var ктоείναι草泥马 = "You dirty horse.",
    happy☺n☺mat☺p☺eia = ":)Yay!",
    ಠ_ಠ = "emoticon";

alert(ктоείναι草泥马 + happy☺n☺mat☺p☺eia + ಠ_ಠ);

但是，出于某种原因，和 不是有效的变量名。◎ܫ◎♨_♨☺

为什么做和工作，但不是，或者？ಠ_ಠ草泥马◎ܫ◎♨_♨☺

网友回答：

ಠ_ಠ
和草泥马仅包含实际字母中使用的“字母”;也就是说，ಠ
是卡纳达字母中的符号，草泥马由汉字组成。

◎ 和 ☺ ，然而，纯粹是符号;它们不与任何字母相关联。

ECMAScript 标准第 7.6 章（除 Internet Explorer 之外的所有浏览器都遵循该标准）规定标识符必须以下列选项之一开头。

• 一个统一码字母
• $或_
• 后跟一个 Unicode 转义序列。

标识符的以下字符必须是以下字符之一。

• 开头允许的任何字符
• 一个统一码组合商标
• 一个统一码数字
• 一个 Unicode 连接器标点符号
• 零宽度非连接器
• 零宽度连接器

IE 超出了标准，并且足够宽松，允许某些符号，例如 ☺ .

有一个工具可以告诉你，根据 ECMAScript 5.1 和 Unicode 6.1，你输入的任何字符串是否是有效的 JavaScript 变量名。

网友回答：

EcmaScript 262 第 7.6 节规定名称必须以 $、_ 或 Unicode 字母开头，之后可以包含这些字符、Unicode 组合标记、Unicode 数字或 Unicode 连接器标点符号（以及几个特定于语言的格式控制字符）。

因此，在您的情况下，允许和不允许的标识符之间的区别可能是前导字符是否被视为“字母”。

网友回答：

为了引用有效的 JavaScript 变量名称，我的文章总结了相关的规范部分：

标识符必须以 、 或 Unicode 类别“大写字母 （Lu）”、“小写字母 （Ll）”、“标题大小写字母 （Lt）”、“修饰符字母 （Lm）”、“其他字母 （Lo）”或“字母编号 （Nl）”中的任何字符开头。$_

字符串的其余部分可以包含相同的字符，以及任何 U+200C 零宽度非连接器字符、U+200D 零宽度连接器字符以及 Unicode 类别“非间距标记 （Mn）”、“间距组合标记 （Mc）”、“十进制数字 （Nd）”或“连接器标点符号 （Pc）”中的字符。

我还创建了一个工具，它会告诉你输入的任何字符串是否是符合 ECMAScript 5.1 和 Unicode 6.3 的有效 JavaScript 变量名：

附言：如果你要用一个只有ASCII的正则表达式来总结所有这些规则，那么它的长度将超过9个字符。在这里：

// ECMAScript 5.1 / Unicode v6.3.0:
/^(?!(?:do|if|in|for|let|new|try|var|case|else|enum|eval|null|this|true|void|with|break|catch|class|const|false|super|throw|while|yield|delete|export|import|public|return|static|switch|typeof|default|extends|finally|package|private|continue|debugger|function|arguments|interface|protected|implements|instanceof)$)[x24A-Zx5Fa-zxAAxB5xBAxC0-xD6xD8-xF6xF8-u02C1u02C6-u02D1u02E0-u02E4u02ECu02EEu0370-u0374u0376u0377u037A-u037Du0386u0388-u038Au038Cu038E-u03A1u03A3-u03F5u03F7-u0481u048A-u0527u0531-u0556u0559u0561-u0587u05D0-u05EAu05F0-u05F2u0620-u064Au066Eu066Fu0671-u06D3u06D5u06E5u06E6u06EEu06EFu06FA-u06FCu06FFu0710u0712-u072Fu074D-u07A5u07B1u07CA-u07EAu07F4u07F5u07FAu0800-u0815u081Au0824u0828u0840-u0858u08A0u08A2-u08ACu0904-u0939u093Du0950u0958-u0961u0971-u0977u0979-u097Fu0985-u098Cu098Fu0990u0993-u09A8u09AA-u09B0u09B2u09B6-u09B9u09BDu09CEu09DCu09DDu09DF-u09E1u09F0u09F1u0A05-u0A0Au0A0Fu0A10u0A13-u0A28u0A2A-u0A30u0A32u0A33u0A35u0A36u0A38u0A39u0A59-u0A5Cu0A5Eu0A72-u0A74u0A85-u0A8Du0A8F-u0A91u0A93-u0AA8u0AAA-u0AB0u0AB2u0AB3u0AB5-u0AB9u0ABDu0AD0u0AE0u0AE1u0B05-u0B0Cu0B0Fu0B10u0B13-u0B28u0B2A-u0B30u0B32u0B33u0B35-u0B39u0B3Du0B5Cu0B5Du0B5F-u0B61u0B71u0B83u0B85-u0B8Au0B8E-u0B90u0B92-u0B95u0B99u0B9Au0B9Cu0B9Eu0B9Fu0BA3u0BA4u0BA8-u0BAAu0BAE-u0BB9u0BD0u0C05-u0C0Cu0C0E-u0C10u0C12-u0C28u0C2A-u0C33u0C35-u0C39u0C3Du0C58u0C59u0C60u0C61u0C85-u0C8Cu0C8E-u0C90u0C92-u0CA8u0CAA-u0CB3u0CB5-u0CB9u0CBDu0CDEu0CE0u0CE1u0CF1u0CF2u0D05-u0D0Cu0D0E-u0D10u0D12-u0D3Au0D3Du0D4Eu0D60u0D61u0D7A-u0D7Fu0D85-u0D96u0D9A-u0DB1u0DB3-u0DBBu0DBDu0DC0-u0DC6u0E01-u0E30u0E32u0E33u0E40-u0E46u0E81u0E82u0E84u0E87u0E88u0E8Au0E8Du0E94-u0E97u0E99-u0E9Fu0EA1-u0EA3u0EA5u0EA7u0EAAu0EABu0EAD-u0EB0u0EB2u0EB3u0EBDu0EC0-u0EC4u0EC6u0EDC-u0EDFu0F00u0F40-u0F47u0F49-u0F6Cu0F88-u0F8Cu1000-u102Au103Fu1050-u1055u105A-u105Du1061u1065u1066u106E-u1070u1075-u1081u108Eu10A0-u10C5u10C7u10CDu10D0-u10FAu10FC-u1248u124A-u124Du1250-u1256u1258u125A-u125Du1260-u1288u128A-u128Du1290-u12B0u12B2-u12B5u12B8-u12BEu12C0u12C2-u12C5u12C8-u12D6u12D8-u1310u1312-u1315u1318-u135Au1380-u138Fu13A0-u13F4u1401-u166Cu166F-u167Fu1681-u169Au16A0-u16EAu16EE-u16F0u1700-u170Cu170E-u1711u1720-u1731u1740-u1751u1760-u176Cu176E-u1770u1780-u17B3u17D7u17DCu1820-u1877u1880-u18A8u18AAu18B0-u18F5u1900-u191Cu1950-u196Du1970-u1974u1980-u19ABu19C1-u19C7u1A00-u1A16u1A20-u1A54u1AA7u1B05-u1B33u1B45-u1B4Bu1B83-u1BA0u1BAEu1BAFu1BBA-u1BE5u1C00-u1C23u1C4D-u1C4Fu1C5A-u1C7Du1CE9-u1CECu1CEE-u1CF1u1CF5u1CF6u1D00-u1DBFu1E00-u1F15u1F18-u1F1Du1F20-u1F45u1F48-u1F4Du1F50-u1F57u1F59u1F5Bu1F5Du1F5F-u1F7Du1F80-u1FB4u1FB6-u1FBCu1FBEu1FC2-u1FC4u1FC6-u1FCCu1FD0-u1FD3u1FD6-u1FDBu1FE0-u1FECu1FF2-u1FF4u1FF6-u1FFCu2071u207Fu2090-u209Cu2102u2107u210A-u2113u2115u2119-u211Du2124u2126u2128u212A-u212Du212F-u2139u213C-u213Fu2145-u2149u214Eu2160-u2188u2C00-u2C2Eu2C30-u2C5Eu2C60-u2CE4u2CEB-u2CEEu2CF2u2CF3u2D00-u2D25u2D27u2D2Du2D30-u2D67u2D6Fu2D80-u2D96u2DA0-u2DA6u2DA8-u2DAEu2DB0-u2DB6u2DB8-u2DBEu2DC0-u2DC6u2DC8-u2DCEu2DD0-u2DD6u2DD8-u2DDEu2E2Fu3005-u3007u3021-u3029u3031-u3035u3038-u303Cu3041-u3096u309D-u309Fu30A1-u30FAu30FC-u30FFu3105-u312Du3131-u318Eu31A0-u31BAu31F0-u31FFu3400-u4DB5u4E00-u9FCCuA000-uA48CuA4D0-uA4FDuA500-uA60CuA610-uA61FuA62AuA62BuA640-uA66EuA67F-uA697uA6A0-uA6EFuA717-uA71FuA722-uA788uA78B-uA78EuA790-uA793uA7A0-uA7AAuA7F8-uA801uA803-uA805uA807-uA80AuA80C-uA822uA840-uA873uA882-uA8B3uA8F2-uA8F7uA8FBuA90A-uA925uA930-uA946uA960-uA97CuA984-uA9B2uA9CFuAA00-uAA28uAA40-uAA42uAA44-uAA4BuAA60-uAA76uAA7AuAA80-uAAAFuAAB1uAAB5uAAB6uAAB9-uAABDuAAC0uAAC2uAADB-uAADDuAAE0-uAAEAuAAF2-uAAF4uAB01-uAB06uAB09-uAB0EuAB11-uAB16uAB20-uAB26uAB28-uAB2EuABC0-uABE2uAC00-uD7A3uD7B0-uD7C6uD7CB-uD7FBuF900-uFA6DuFA70-uFAD9uFB00-uFB06uFB13-uFB17uFB1DuFB1F-uFB28uFB2A-uFB36uFB38-uFB3CuFB3EuFB40uFB41uFB43uFB44uFB46-uFBB1uFBD3-uFD3DuFD50-uFD8FuFD92-uFDC7uFDF0-uFDFBuFE70-uFE74uFE76-uFEFCuFF21-uFF3AuFF41-uFF5AuFF66-uFFBEuFFC2-uFFC7uFFCA-uFFCFuFFD2-uFFD7uFFDA-uFFDC][x240-9A-Zx5Fa-zxAAxB5xBAxC0-xD6xD8-xF6xF8-u02C1u02C6-u02D1u02E0-u02E4u02ECu02EEu0300-u0374u0376u0377u037A-u037Du0386u0388-u038Au038Cu038E-u03A1u03A3-u03F5u03F7-u0481u0483-u0487u048A-u0527u0531-u0556u0559u0561-u0587u0591-u05BDu05BFu05C1u05C2u05C4u05C5u05C7u05D0-u05EAu05F0-u05F2u0610-u061Au0620-u0669u066E-u06D3u06D5-u06DCu06DF-u06E8u06EA-u06FCu06FFu0710-u074Au074D-u07B1u07C0-u07F5u07FAu0800-u082Du0840-u085Bu08A0u08A2-u08ACu08E4-u08FEu0900-u0963u0966-u096Fu0971-u0977u0979-u097Fu0981-u0983u0985-u098Cu098Fu0990u0993-u09A8u09AA-u09B0u09B2u09B6-u09B9u09BC-u09C4u09C7u09C8u09CB-u09CEu09D7u09DCu09DDu09DF-u09E3u09E6-u09F1u0A01-u0A03u0A05-u0A0Au0A0Fu0A10u0A13-u0A28u0A2A-u0A30u0A32u0A33u0A35u0A36u0A38u0A39u0A3Cu0A3E-u0A42u0A47u0A48u0A4B-u0A4Du0A51u0A59-u0A5Cu0A5Eu0A66-u0A75u0A81-u0A83u0A85-u0A8Du0A8F-u0A91u0A93-u0AA8u0AAA-u0AB0u0AB2u0AB3u0AB5-u0AB9u0ABC-u0AC5u0AC7-u0AC9u0ACB-u0ACDu0AD0u0AE0-u0AE3u0AE6-u0AEFu0B01-u0B03u0B05-u0B0Cu0B0Fu0B10u0B13-u0B28u0B2A-u0B30u0B32u0B33u0B35-u0B39u0B3C-u0B44u0B47u0B48u0B4B-u0B4Du0B56u0B57u0B5Cu0B5Du0B5F-u0B63u0B66-u0B6Fu0B71u0B82u0B83u0B85-u0B8Au0B8E-u0B90u0B92-u0B95u0B99u0B9Au0B9Cu0B9Eu0B9Fu0BA3u0BA4u0BA8-u0BAAu0BAE-u0BB9u0BBE-u0BC2u0BC6-u0BC8u0BCA-u0BCDu0BD0u0BD7u0BE6-u0BEFu0C01-u0C03u0C05-u0C0Cu0C0E-u0C10u0C12-u0C28u0C2A-u0C33u0C35-u0C39u0C3D-u0C44u0C46-u0C48u0C4A-u0C4Du0C55u0C56u0C58u0C59u0C60-u0C63u0C66-u0C6Fu0C82u0C83u0C85-u0C8Cu0C8E-u0C90u0C92-u0CA8u0CAA-u0CB3u0CB5-u0CB9u0CBC-u0CC4u0CC6-u0CC8u0CCA-u0CCDu0CD5u0CD6u0CDEu0CE0-u0CE3u0CE6-u0CEFu0CF1u0CF2u0D02u0D03u0D05-u0D0Cu0D0E-u0D10u0D12-u0D3Au0D3D-u0D44u0D46-u0D48u0D4A-u0D4Eu0D57u0D60-u0D63u0D66-u0D6Fu0D7A-u0D7Fu0D82u0D83u0D85-u0D96u0D9A-u0DB1u0DB3-u0DBBu0DBDu0DC0-u0DC6u0DCAu0DCF-u0DD4u0DD6u0DD8-u0DDFu0DF2u0DF3u0E01-u0E3Au0E40-u0E4Eu0E50-u0E59u0E81u0E82u0E84u0E87u0E88u0E8Au0E8Du0E94-u0E97u0E99-u0E9Fu0EA1-u0EA3u0EA5u0EA7u0EAAu0EABu0EAD-u0EB9u0EBB-u0EBDu0EC0-u0EC4u0EC6u0EC8-u0ECDu0ED0-u0ED9u0EDC-u0EDFu0F00u0F18u0F19u0F20-u0F29u0F35u0F37u0F39u0F3E-u0F47u0F49-u0F6Cu0F71-u0F84u0F86-u0F97u0F99-u0FBCu0FC6u1000-u1049u1050-u109Du10A0-u10C5u10C7u10CDu10D0-u10FAu10FC-u1248u124A-u124Du1250-u1256u1258u125A-u125Du1260-u1288u128A-u128Du1290-u12B0u12B2-u12B5u12B8-u12BEu12C0u12C2-u12C5u12C8-u12D6u12D8-u1310u1312-u1315u1318-u135Au135D-u135Fu1380-u138Fu13A0-u13F4u1401-u166Cu166F-u167Fu1681-u169Au16A0-u16EAu16EE-u16F0u1700-u170Cu170E-u1714u1720-u1734u1740-u1753u1760-u176Cu176E-u1770u1772u1773u1780-u17D3u17D7u17DCu17DDu17E0-u17E9u180B-u180Du1810-u1819u1820-u1877u1880-u18AAu18B0-u18F5u1900-u191Cu1920-u192Bu1930-u193Bu1946-u196Du1970-u1974u1980-u19ABu19B0-u19C9u19D0-u19D9u1A00-u1A1Bu1A20-u1A5Eu1A60-u1A7Cu1A7F-u1A89u1A90-u1A99u1AA7u1B00-u1B4Bu1B50-u1B59u1B6B-u1B73u1B80-u1BF3u1C00-u1C37u1C40-u1C49u1C4D-u1C7Du1CD0-u1CD2u1CD4-u1CF6u1D00-u1DE6u1DFC-u1F15u1F18-u1F1Du1F20-u1F45u1F48-u1F4Du1F50-u1F57u1F59u1F5Bu1F5Du1F5F-u1F7Du1F80-u1FB4u1FB6-u1FBCu1FBEu1FC2-u1FC4u1FC6-u1FCCu1FD0-u1FD3u1FD6-u1FDBu1FE0-u1FECu1FF2-u1FF4u1FF6-u1FFCu200Cu200Du203Fu2040u2054u2071u207Fu2090-u209Cu20D0-u20DCu20E1u20E5-u20F0u2102u2107u210A-u2113u2115u2119-u211Du2124u2126u2128u212A-u212Du212F-u2139u213C-u213Fu2145-u2149u214Eu2160-u2188u2C00-u2C2Eu2C30-u2C5Eu2C60-u2CE4u2CEB-u2CF3u2D00-u2D25u2D27u2D2Du2D30-u2D67u2D6Fu2D7F-u2D96u2DA0-u2DA6u2DA8-u2DAEu2DB0-u2DB6u2DB8-u2DBEu2DC0-u2DC6u2DC8-u2DCEu2DD0-u2DD6u2DD8-u2DDEu2DE0-u2DFFu2E2Fu3005-u3007u3021-u302Fu3031-u3035u3038-u303Cu3041-u3096u3099u309Au309D-u309Fu30A1-u30FAu30FC-u30FFu3105-u312Du3131-u318Eu31A0-u31BAu31F0-u31FFu3400-u4DB5u4E00-u9FCCuA000-uA48CuA4D0-uA4FDuA500-uA60CuA610-uA62BuA640-uA66FuA674-uA67DuA67F-uA697uA69F-uA6F1uA717-uA71FuA722-uA788uA78B-uA78EuA790-uA793uA7A0-uA7AAuA7F8-uA827uA840-uA873uA880-uA8C4uA8D0-uA8D9uA8E0-uA8F7uA8FBuA900-uA92DuA930-uA953uA960-uA97CuA980-uA9C0uA9CF-uA9D9uAA00-uAA36uAA40-uAA4DuAA50-uAA59uAA60-uAA76uAA7AuAA7BuAA80-uAAC2uAADB-uAADDuAAE0-uAAEFuAAF2-uAAF6uAB01-uAB06uAB09-uAB0EuAB11-uAB16uAB20-uAB26uAB28-uAB2EuABC0-uABEAuABECuABEDuABF0-uABF9uAC00-uD7A3uD7B0-uD7C6uD7CB-uD7FBuF900-uFA6DuFA70-uFAD9uFB00-uFB06uFB13-uFB17uFB1D-uFB28uFB2A-uFB36uFB38-uFB3CuFB3EuFB40uFB41uFB43uFB44uFB46-uFBB1uFBD3-uFD3DuFD50-uFD8FuFD92-uFDC7uFDF0-uFDFBuFE00-uFE0FuFE20-uFE26uFE33uFE34uFE4D-uFE4FuFE70-uFE74uFE76-uFEFCuFF10-uFF19uFF21-uFF3AuFF3FuFF41-uFF5AuFF66-uFFBEuFFC2-uFFC7uFFCA-uFFCFuFFD2-uFFD7uFFDA-uFFDC]*$/