0
241
ViewsSome regular expressions I've been studying
I've found these regex elsewhere:
myString.replace(/^.*\//, '');
myString.replace(/\..*?$/, '');
My question is:
- do
^and?$make any sense here?
And my interpretation is that ^ isn't relevant, because we are using .* which means "anything".
The second one means replace from the . any character in lazy mode till the end of the string. Which is the same as nothing.
So I'd write them:
myString.replace(/.*\//, '');
myString.replace(/\..*/, '');
But I am not 100% sure as my Regex is quite basic. Ideas?
2 answers
Answer question0
Indeed, in the first regular expression the ^ is not really needed. The effect is the same without it.
However, in the second regular expression there is a difference when you omit the ? and the $, because . does not match newline characters (unless you add s as modifier).
See the different results:
let myString = `.this
is multiline`;
console.log(myString.replace(/\..*?$/, ''));
console.log(myString.replace(/\..*/, ''));0
And my interpretation is that ^ isn't relevant, because we are using .* which means "anything".
Yep, that's the start of the string, but if you're wanting all of the string it has no relevance. Also, go here for a great regex playground.
do ^ and ?$ make any sense here?
To answer the second question, for regex /\..*?$/, the ?$ does not make sense with *, b/c x* means 0 or more of x and x? means 0 or 1 (unless you intentionally wanted 0 or 1 of 0 or more, but doubt that). This is taken directly from the help sheet on regexr.com.
