@woosh/meep-engine/src/core/collection/array/array_copy_unique.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 * Copy data from one array to another if they are not present in the destination array
 * @template T
 * @param {T[]} source The source array
 * @param {number} source_position Starting position where to copy from inside the source array
 * @param {T[]} destination The destination array
 * @param {number} destination_position Starting position where to copy to inside the destination array
 * @param {number} length How many elements should be copied
 * @returns {number} unique addition count
 */
export function array_copy_unique(source, source_position, destination, destination_position, length) {

    let j = destination_position;
    let k = 0;

    for (; k < length; k++) {
        const source_index = source_position + k;

        const element = source[source_index];

        const p = destination.indexOf(element);
        if (p === -1 || p >= j) {
            destination[j] = element;
            j++;
        }

    }

    return j - destination_position;
}