нужно объяснение кода

$(document).ready(function(){
$('#cfact p').click(function(){$('#cfact p').removeClass('active');var color=$(this).attr('rel');$(this).addClass('active');$('#cshadow img').attr('src',color);});
$('input#size-x').keypress(function(event){
var key,keyChar;
if(!event)var event=window.event;
if(event.keyCode)key=event.keyCode;
else if(event.which)key=event.which;
if(key==null||key==0||key==8||key==13||key==9||key==46||key==37||key==39)return true;
keyChar=String.fromCharCode(key);
if(!/\d/.test(keyChar))return false;
});
$('input#size-y').keypress(function(event){
var key,keyChar;if(!event)var event=window.event;
if(event.keyCode)key=event.keyCode;
else if(event.which)key=event.which;
if(key==null||key==0||key==8||key==13||key==9||key==46||key==37||key==39)return true;
keyChar=String.fromCharCode(key);
if(!/\d/.test(keyChar))return false;
});
$("input#size-y").keyup(function(){
var value2=$("input#size-y").val();
var value1=$("input#size-x").val();
if(value2>maxvertical){
$("#slider-y").slider("value",value2);
$("input#size-y").val("3000");
sheight=3000;
prices();
}else if(value2<minvertical&&value2&&value2!=0&&value1!=0&&value1)
{
$("#slider-y").slider("value",value2);
sheight=1850;
prices();
}else if(!value2||value2==0||!value1||value1==0){
$("#slider-y").slider("value",value2);
sheight=2;
nul();
}else{
sheight=value2;
$("#slider-y").slider("value",value2);
prices();
}});
$("input#size-x").keyup(function(){
var value2=$("input#size-x").val();
var value1=$("input#size-y").val();
if(value2>maxhotizontal){
$("#slider-x").slider("value",value2);
$("input#size-x").val("6000");
swidth=3000;prices();
}else if(value2<minhotizontal&&value2&&value2!=0&&value1&&value1!=0){
$("#slider-x").slider("value",value2);
swidth=2250;
prices();
}else if(!value2||value2==0||!value1||value1==0){
$("#slider-x").slider("value",value2);
swidth=2250;
nul();
}else{
swidth=value2;
$("#slider-x").slider("value",value2);
prices();
}});
$("#cfact p").click(function(){
$(this).parent().find("p").removeClass("active");
$(this).addClass("active");
var faktura=$(this).attr('rell');
$("#cgg img").attr('src',faktura);
});
prices();
});
var calcsek={
'r1':{
 
1875:[449,457,466,485,500,527,539,566,568,583,580,614,663,713,763,796,782,815,866,884,868,911,956,972,951,996,1041,1062,1062,1083,1150,1220,1207,1229,1288],
2000:[462,470,495,502,509,485,518,539,568,623,659,671,681,721,759,809,817,852,878,905,898,951,969,995,992,1042,1052,1086,1108,1129,1147,1196,1219,1280,1237],
2125:[482,490,500,504,515,491,520,542,572,605,636,669,681,679,713,795,808,816,842,887,897,898,927,984,1002,1009,1025,1045,1089,1167,1085,1151,1196,1336,1179],
2250:[498,509,509,509,519,501,520,540,575,597,630,662,696,679,761,788,809,792,825,847,886,873,907,956,995,977,1004,1030,1103,1190,1088,1136,1213,1361,1183],
2375:[510,519,545,555,562,540,535,561,571,627,658,695,747,714,770,814,855,809,843,882,926,887,916,971,1028,945,982,1051,1148,1325,1162,1234,1331,1476,1277],
2500:[545,557,585,594,602,642,563,597,642,636,670,718,818,922,965,960,981,1005,1018,1042,1067,1088,1150,1185,1181,1238,1262,1289,1314,1366,1451,1478,1505,1563,1590],
2625:[557,568,590,600,610,663,569,599,650,648,683,755,821,934,969,990,994,1046,1051,1060,1082,1112,1167,1200,1214,1271,1324,1323,1346,1430,1491,1516,1544,1637,1632],
2750:[575,587,592,604,609,661,579,610,658,679,711,759,821,943,992,984,993,1067,1085,1095,1108,1149,1199,1205,1220,1294,1335,1358,1390,1470,1499,1542,1586,1681,1662],
2875:[631,643,677,689,705,726,659,690,786,742,911,926,934,991,1042,1054,1079,1107,1207,1199,1199,1236,1283,1301,1331,1353,1410,1465,1494,1555,1617,1666,1694,1744,1811],
3000:[648,662,694,706,709,764,817,837,852,921,900,930,957,1049,1104,1118,1145,1216,1269,1261,1276,1312,1365,1370,1400,1440,1487,1547,1574,1671,1739,1792,1823,1876,1927]}};
function prices(){
        sheight=(Math.abs((Math.ceil((sheight)/125))*125));
var koef=Math.abs(Math.ceil((swidth)/125)-14);
price=calcsek['r1'][sheight][koef];
price*=78;
price*=0.97;
if($('input[name="avtomatika"]').prop('checked'))
{price+=16000;}
if($('input[name="montazsek"]').prop('checked'))
{price+=9000;}
runner();
}
 
function nul(){price=0;runner();}
var swidth=2500;
var sheight=2750;
var price=0;
var symm=0;
var minhotizontal=2250;
var maxhotizontal=3000;
var minvertical=1850;
var maxvertical=3000;
var eu;
$("#slider-y").slider({
orientation:'vertical',
min:1850,
max:3000,
step:125,
range:"min",
animate:true,
 
slide:function(event,ui){
$("#size-ys").html(ui.value);
sheight=$(this).slider("option","value");
if((sheight)>minvertical&&((sheight)<maxvertical))
{$("#size-y").val(ui.value);}},
change:function(event,ui){$("#size-ys").html(ui.value);sheight=$(this).slider("option","value");
if((sheight)>minvertical&&((sheight)<maxvertical))
{$("#size-y").val(ui.value);}},
stop:function(){
sheight=$(this).slider("option","value");
prices();
}}).slider("option","value",sheight);
$("#slider-x").slider({
step:250,
min:2250,
max:3000,
range:"min",
animate:true,
slide:function(event,ui){$("#size-xs").html(ui.value);
swidth=$(this).slider("option","value");
if(swidth>minhotizontal&&swidth<maxhotizontal)
{$("#size-x").val(ui.value);}},
change:function(event,ui){$("#size-xs").html(ui.value);
swidth=$(this).slider("option","value");
if(swidth>minhotizontal&&swidth<maxhotizontal){
$("#size-x").val(ui.value);}},
stop:function(){swidth=$(this).slider("option","value");prices();
}}).slider("option","value",swidth);
function runner(){
if(price!=symm){
var timer,intv=25,msecs=1000,ticks=msecs/intv,totalTicks=ticks;var currents=symm;
var deltas=(price-currents)/ticks;
timer=setInterval(function(){
if(ticks<=0){clearInterval(timer);}
var tickKoef=0;tickKoef=totalTicks-ticks;
$(".price-r.sek").html(Math.round(currents+tickKoef*deltas)+" р.-");
ticks--},intv);symm=price;}
$("#ajax-zacaz-form input[name='width']").val($("#size-x").val());
$("#ajax-zacaz-form input[name='height']").val($("#size-y").val());
$("#ajax-zacaz-form input[name='price']").val(Math.round(price));
if($('input[name="avtomatika"]').prop('checked'))
{$("#ajax-zacaz-form input[name='avtom']").val("С автоматикой")}
else{
$("#ajax-zacaz-form input[name='avtom']").val("Без автоматики")}}
$(document).ready(function(){
$(".avgrs").click(function(){
$(".avgrs label").toggleClass("vibrana-av");
var value2=$("input#size-x").val();
var value1=$("input#size-y").val();
if(!value2||value2==0||!value1||value1==0){nul();}else{prices();}
});
$(".montazsek").click(function(){
$(".montazsek label").toggleClass("vibrana-mon");
var value2=$("input#size-x").val();
var value1=$("input#size-y").val();
if(!value2||value2==0||!value1||value1==0){nul();}else{prices();}
});
$("#color li").click(function(){var nomer=$(this).attr("rell");$("#mainImg img[style*='display:block;']").fadeOut();$("#mainImg img").eq(nomer).fadeIn();});
});