JavaScript game development: "The Legend of Cao Cao" Parts Development (V) Implementation of movable maps

var subtractedMargin = 0;
var subtractedMarginL = 0;
var mousedown = 0;

var toright;
var toleft;
var todown;
var toup;

= function(){
mousedown = 0;

clearInterval(toright);
clearInterval(toleft);
clearInterval(todown);
clearInterval(toup);
}

function mapMove(direction)
{
switch(direction){
case "down":
subtractedMargin -= 15;

$("#ID_IMG_MAP").animate({marginTop: subtractedMargin + "px"}, 120);

break;

case "up":
subtractedMargin += 15;

$("#ID_IMG_MAP").animate({marginTop: subtractedMargin + "px"}, 120);

break;

case "right":
subtractedMarginL -= 15;

$("#ID_IMG_MAP").animate({marginLeft: subtractedMarginL + "px"}, 120);

break;

case "left":
subtractedMarginL += 15;

$("#ID_IMG_MAP").animate({marginLeft: subtractedMarginL + "px"}, 120);

break;
}

if(subtractedMarginL < -415){
clearInterval(toright);
clearInterval(toleft);
}
if(subtractedMarginL > -20){
clearInterval(toright);
clearInterval(toleft);
}

if(subtractedMargin < -640){
clearInterval(todown);
clearInterval(toup);
}
if(subtractedMargin > -20){
clearInterval(todown);
clearInterval(toup);
}
}

$("body").ready(function(){
$("#ID_DIV_TORIGHT").mousedown(function(){
mousedown = 1;

if(subtractedMarginL > -415 && mousedown == 1){
mapMove("right");
toright = setInterval(function(){mapMove("right");}, 120);
}

});

$("#ID_DIV_TOLEFT").mousedown(function(){
mousedown = 1;

if(subtractedMarginL < -20 && mousedown == 1){
mapMove("left");
toleft = setInterval(function(){mapMove("left");}, 120);
}
});

$("#ID_DIV_TODOWN").mousedown(function(){
mousedown = 1;

if(subtractedMargin > -640 && mousedown == 1){
mapMove("down");
todown = setInterval(function(){mapMove("down");}, 120);
}
});

$("#ID_DIV_TOUP").mousedown(function(){
mousedown = 1;

if(subtractedMargin < -20 && mousedown == 1){
mapMove("up");
toup = setInterval(function(){mapMove("up");}, 120);
}
});
});