Symbol.search - JavaScript

Symbol.search - JavaScript | MDN

Try it

class Search1 {
  constructor(value) {
    this.value = value;
  }
  [Symbol.search](string) {
    return string.indexOf(this.value);
  }
}

console.log("foobar".search(new Search1("bar")));
// Expected output: 3

Value

The well-known symbol Symbol.search.

Property attributes of `Symbol.search`
Writable	no
Enumerable	no
Configurable	no

Examples

Custom string search

class CaseInsensitiveSearch {
  constructor(value) {
    this.value = value.toLowerCase();
  }
  [Symbol.search](string) {
    return string.toLowerCase().indexOf(this.value);
  }
}

console.log("foobar".search(new CaseInsensitiveSearch("BaR"))); // 3