javascript - 为什么2 + 40等于42？(Why does 2+?40 equal 42?)

Question

I was baffled when a colleague showed me this line of JavaScript alerting 42.(当一位同事向我展示这一行警告42时，我感到很困惑。)

 alert(2+ 40); 

It quickly turns out that what looks like a minus sign is actually an arcane Unicode character with clearly different semantics.(事实证明，看起来像减号的实际上是一个神秘的Unicode字符，具有明显不同的语义。)

This left me wondering why that character doesn't produce a syntax error when the expression is parsed.(这让我想知道为什么该字符在解析表达式时不会产生语法错误。)

I'd also like to know if there are more characters behaving like this.(我还想知道是否有更多的人物表现得像这样。)   ask by GOTO 0 translate from so

Answer 1

That character is "OGHAM SPACE MARK" , which is a space character.(那个角色是“OGHAM SPACE MARK” ，这是一个空间角色。)

So the code is equivalent to alert(2+ 40) .(所以代码相当于alert(2+ 40) 。)

I'd also like to know if there are more characters behaving like this.(我还想知道是否有更多的人物表现得像这样。)

Any Unicode character in the Zs class is a white space character in JavaScript , but there don't seem to be that many .(Zs类中的任何Unicode字符都是JavaScript中的空白字符 ， 但似乎没有那么多 。)

However, JavaScript also allows Unicode characters in identifiers , which lets you use interesting variable names like ?_? .(但是， JavaScript还允许在标识符中使用Unicode字符 ，这使您可以使用有趣的变量名称，如?_? 。)