function becomingBigger() {
    if(switchOfAnimation) {
        footer.firstElementChild.style.cssText = "-webkit-transform:scale(1.5);\
                                                  -moz-transform:scale(1.5);\
                                                  -ms-transform:scale(1.5);\
                                                  -o-transform:scale(1.5);\
                                                  transform:scale(1.5);";
        setTimeout(becomingSmaller, 21000);
    } else return;
}

function becomingSmaller() {
    if(switchOfAnimation) {
        footer.firstElementChild.style.cssText = "-webkit-transform:scale(1);\
                                                  -moz-transform:scale(1);\
                                                  -ms-transform:scale(1);\
                                                  -o-transform:scale(1);\
                                                  transform:scale(1);";
        setTimeout(becomingBigger, 21000);
    } else return;
}

//Анимируем header & main part of article & footer of article
function animation() {
    if(!switchOfAnimation && footer.getBoundingClientRect().top / window.innerHeight < 0.6 && footer.getBoundingClientRect().top >= 0) {
        switchOfAnimation = true;
        becomingBigger();
    } else if((switchOfAnimation && footer.getBoundingClientRect().top / window.innerHeight > 0.6) || footer.getBoundingClientRect().top < 0) {
        switchOfAnimation = false;
        footer.firstElementChild.style.cssText = "-webkit-transform:scale(1);\
                                                  -moz-transform:scale(1);\
                                                  -ms-transform:scale(1);\
                                                  -o-transform:scale(1);\
                                                  transform:scale(1);";
    }
}

window.addEventListener('load', animation, false);