Why don’t you check the direction
before you do your calculations? Something like:
function slope(x1,y1,x2,y2,ex,direction){
if(direction == "right"){
var gg1 = x2-x1;
var gg2 = y2-y1;
var ggs = gg2/gg1;
var ggsR = gg1/gg2;
console.log(ggsR);
return(ggs);
}
else if(direction == "left"){
//do something else
}
};