function?sameSign(a,?b){
?return(a?^?b)?>=0
}
//位運(yùn)算，判斷符號(hào)是否相同a異或b
function?vector(a,?b){
?return?{
??x:?b.x?-?a.x,
??y:?b.y?-?a.y
?}
}
//向量的坐標(biāo)
//向量的差乘公式
function?vectorProduct(v1,v2){
?return?v1.x?*?v2.y?-?v2.x?*v1.y
}
function?isPointInTrangle(p,a,b,c)?{
?var?pa?=?vector(p,a)
?var?pb?=?vector(p,b)
?var?pc?=?vector(p,c)
?var?t1?=?vectorProduct(pa,pb)
?var?t2?=?vectorProduct(pb,pc)
?var?t3?=?vectorProduct(pc,pa)
?return?sameSign(t1,t2)?&&?sameSign(t2,t3)
}
function?needDelay(elem,leftCorner,currMoussePos)?{
?var?offset?=?elem.offset()
?//offset方法來(lái)獲取二級(jí)菜單上下邊緣的坐標(biāo)
?var?topleft?=?{
??x:?offset.left,
??y:?offset.top?
?}
?var?bottomleft?=?{
??x:?offset.left,
??y:?offset.top?+?elem.height()
?}
?return?isPointInTrangle(currMoussePos,leftCorner,topleft,bottomleft)
}