What about the syntax of this regular expression is Visual Studio warning about?

Question

var STRIP_PHN_REG_EX = /[\x\X\(\)\.\-\s\',]/g;

Visual Studio gives the following not-very-detailed warning: "Syntax error in regular expression"

However, the regular expression runs fine. What am I missing here?

Answer 1

\\x and \\X are not valid here. \\x can be used with two hexadecimal digits to identify a specific character — for example, \\x09 means the tab character ( \\t ) — but you're not using it that way here; and \\X has no uses in JavaScript regexes.

But since I can't tell what you want the regex to do, I can't tell you how to fix it. Maybe you just meant

var STRIP_PHN_REG_EX = /[xX().\-\s',]/g;

? (That matches any whitespace character, as well as any of x , X , ( , ) , . , - , ' , , .)

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Edited to add: Or maybe by \\x and \\X you meant "lowercase hex digit" and "uppercase hex digit", respectively? There's no special syntax for that in JavaScript, but you can write:

var STRIP_PHN_REG_EX = /[0-9a-fA-F().\-\s',]/g;