Array().fill acts weirdly

// Option 1
    function initialize() {
        let matrix = new Array(3).fill(["-", "-", "-"]);
        return matrix;
    };
// Option 2
    function initialize() {
        let matrix = new Array();
        for (; matrix.length < 3;) {
            let row = ["-", "-", "-"];
            matrix.push(row);
        };
        return matrix;
    };