JS load whole page AJAX instead of elements?

Question

AJAX

r.soft.bz/miram123
When you select the markup of goods, js immerses the entire site again.
Where is the conflict created?
Help me please.

Answer 1

$('#mainContainer').load('index.php?route='+type+cat_id+href,function(){
  spinner();simpleSliderCust('#mainContainer');sliderBtnHover();svgFix();fancyFastCart();
});

Pour everything that came into the '#mainContainer' container , and the whole page came.
Give only the contents of the container from the server or something)