javascript - if(!q || q === '*') why wildcard use as a string here?

Question

search(q: string): Observable<any> {
if(!q || q === '*') {
  q = '';
} else {
  q = q.toLowerCase();
}

In if condition, why wildcard use as a string here? Please explain this things.

question from:https://stackoverflow.com/questions/65931123/ifq-q-why-wildcard-use-as-a-string-here

Answer 1

regular expression search for empty value, including spaces and tabs /^s*$/ . Regular expressions do not exclusively use "*", this is the number of matches from 0 to infinity.

console.log(/^s*$/.test(""));
console.log(/^s*$/.test(" "));
console.log(/^s*$/.test("*"));