Method _getIndexForValue

src/cdk/listbox/listbox.ts:943–956

* Gets the index of the given value in the given list of options. * @param cache The cache of indices found so far * @param value The value to find * @return The index of the value in the options list

(cache: Map<T, number>, value: T)

   * @return The index of the value in the options list
   */
  private _getIndexForValue(cache: Map<T, number>, value: T) {
    const isEqual = this.compareWith || Object.is;
    if (!cache.has(value)) {
      let index = -1;
      for (let i = 0; i < this.options.length; i++) {
        if (isEqual(value, this.options.get(i)!.value)) {
          index = i;
          break;
        }
      }
      cache.set(value, index);
    }
    return cache.get(value)!;
  }

  /**
   * Handle the user clicking an option.