/**
 * 
 * @param {*} card   字符串类型
 * @returns 
 */
function changeEighteenToFivteen(card) {
    if (card == null || card == "") {
        return true;
    }
    if (card.length == '18') {
        card = card.substr(0, 6) + card.substr(8, 9);
        return card;
    }
}

// 使用方法
changeEighteenToFivteen('440158435915278651')