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。这让我很开心，我非常高兴我可以写出这样有趣的满载unicode的代码:
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);
但由于某些原因，◎ܫ◎、♨_♨和天都不是有效的变量名。
为什么ಠ_ಠ和草泥马可以工作，而不是◎ܫ◎，♨_♨或☺?
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，或者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)。
所以，在你的情况下，允许和不允许的标识符之间的区别可能是先导字符是否被视为“字母”。
ಠ_ಠ 草泥马只包含实际字母表中使用的“字母”;即ಠ 是来自卡纳达语的符号，草泥马由汉字组成。
◎和“天都”是纯粹的符号;它们与任何字母都没有关联。
ECMAScript标准第7.6章(除了Internet Explorer以外的所有浏览器都遵循该标准)规定标识符必须以以下之一开头。
Unicode字母 $或_ \后面跟着一个unicode转义序列。
标识符的以下字符必须为以下字符之一。
开头允许的任何字符 Unicode组合标记 Unicode数字 Unicode连接器标点符号 一个zero-width-non-joiner 零宽度细木工
IE超越了标准，允许使用一些符号，比如☺。
有一个工具可以告诉您输入的任何字符串是否是符合ECMAScript 5.1和Unicode 6.1的有效JavaScript变量名。
引用有效的JavaScript变量名，我的文章总结了相关的规范部分:
An identifier must start with $, _, or any character in the Unicode categories “Uppercase letter (Lu)”, “Lowercase letter (Ll)”, “Titlecase letter (Lt)”, “Modifier letter (Lm)”, “Other letter (Lo)”, or “Letter number (Nl)”. The rest of the string can contain the same characters, plus any U+200C zero width non-joiner characters, U+200D zero width joiner characters, and characters in the Unicode categories “Non-spacing mark (Mn)”, “Spacing combining mark (Mc)”, “Decimal digit number (Nd)”, or “Connector punctuation (Pc)”.
我还创建了一个工具，可以告诉你输入的任何字符串是否符合ECMAScript 5.1和Unicode 6.3的有效JavaScript变量名:
附注:如果将所有这些规则总结为JavaScript的一个ascii正则表达式，那么它的长度将超过9000个字符。下面就是:
// ECMAScript 5.1 / Unicode v6.3.0:
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