aureooms/js-merging

export function _merge ( index, copy ) {

    let merge = function ( compare, a, ai, aj, b, bi, bj, c, ci ) {

        let o = ci - ai - bi;
        let t = ai;

        for ( ; bi < bj ; ++bi ) {

            let q = index( compare, a, ai, aj, b[bi] );
            ai = q[0] + q[1];

            copy( a, t, ai, c, o + t + bi );

            c[o + ai + bi] = b[bi];
            t = ai;
        }

        copy( a, t, aj, c, o + t + bi );
    };

    return merge;

}