how i can to do that, without ternary operator [closed]

function dayOfProgrammer(year) {
 
    let isLeefYeer = year % 4 === 0
        ? year % 100 === 0 ? !!(year < 1918 || year % 400 === 0) : true
        : false;


    return `${year === 1918 ? 26 : isLeefYeer ? 12 : 13}.09.${year}`;
}