在javascript正则表达式中匹配文字特殊字符

Question

For some reason this:

RegExp('\*').test($var)

gives the following error:

SyntaxError: Invalid regular expression: /*/: Nothing to repeat

It looks like the engine doesn't like how I escaped the special character. Is this not the correct way of escaping?

Answer 1

You are trying to match a literal asterisk, but in fact you are applying a * quantifier on the start of string since there is only 1 slash in your regex that is not enough to escape the asterisk for the regex engine.

Use

/\*/.test($var);

Or

RegExp('\\*').test($var)

However, the literal notation is preferred since you are not building the regexp pattern dynamically (ie the pattern is known at design-time).