寻找数组中某个元素的坐标

    /**

     * Returns the index of the first occurrence of a value in an array, or -1 if it is not present.

     * @param searchElement The value to locate in the array.

     * @param fromIndex The array index at which to begin the search. If fromIndex is omitted, the search starts at index 0.

     */

    indexOf(searchElement: T, fromIndex?: number): number;