javascript - How to order chess-moves properly based on the evaluation of the board

Question

I'm trying to make a function that sort moves based on the evaluation of the board and it seems not efficient because when I concant listA and listB some index have undefined value and I can't find the reason why so I asked this.

Here's my sort function:

function sortMoves(chess)
{
    const listA = [], listB = chess.moves();
    const scores = [];

    const start = Date.now();
    // calc best moves
    const moves = listB;
    for (const i in moves)
    {
        const state = chess.move(moves[i], {
            promotion: 'q'
        });
        scores.push(evaluate(chess.board())); // Should I really set the score to the evaluation of the board?
        chess.undo();
    }

    // sort move
    // sort the first 6 moves
    for (var i = 0; i < Math.min(6, listB.length); i++)
    {
        let maxEval = -Infinity;
        let maxIndex = 0;
      
        // loop through the scores arr
        // and find the maxEval
        for (var j = 0; j < scores.length; j++)
        {
            if (scores[j] > maxEval)
            {
                maxEval = scores[j];
                maxIndex = j;
            }
        }
        
   
        scores[maxIndex] = -Infinity;
        
        // put the best score in listA
        listA.push(moves[maxIndex]);
        // remove it on listB
        listB.splice(maxIndex, 1);
    }
    
    // in return, some values is undefined
    return listA.concat(listB);
}

EDIT: I found the bug, when I do splice on listB, it also affects the moves arr since I initialized it as moves = listB so what I did is moves = [...listB]

But I don't think it worked because I when I tried moves = sortMoves(chess), it's slower than normal like moves = chess.moves()

So is there another problem in my sorting function?

EDIT2: It's actually the sortMoves() it self is what it lags, I tried adding up all cut offs. When there's no sort moves. e4 depth3 takes 520 cutoffs but with the sortMoves() it takes 550 cutoffs.

question from:https://stackoverflow.com/questions/65840690/how-to-order-chess-moves-properly-based-on-the-evaluation-of-the-board

Answer 1

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