JS: String.prototype.search

str.search(regex_or_str)

Return the index of first char of matched string. If no match, returns -1.
If argument is string, it is converted to regex by RegExp

const x = "a 99 b";

// find digit
console.log(x.search(/\d/) === 2);
// true

// using string as arg
console.log(x.search("\\d") === 2);
// true

// not found
console.log(x.search("ttt") === -1);
// true