gps - Javascript solution for user being inside or outside a rectangle -

i checking stackoverflow , many other pages find javascript (or jquery) solution tells me if user (with current gps location) inside or outside predefined rectangle on map. there many solutions circles , squares can't find solution rectangles. furthermore rectangle must not parallel f.e. equator. can have possible angle it. parameter of rectangle required make inside/outside calculation? knows javascript solution solve problem?

to know if point inside rectangle in 2d plan need:

• the position of 1 point of rectangle: x0, y0;
• the angle rectangle making horizontal axis: a;
• the length of first side: l1;
• the length of second side: l2.

see drawing.

a point (x,y) inside rectangle when:

• 0 >= (x-x0)*cos(a) - (y-y0)*sin(a) >= l1
• 0 >= (x-x0)*sin(a) + (y-y0)*cos(a) >= l2

or in javascript:

function isinrectangle(x, y, x0, y0, a, l1, l2) {     var v1 = (x-x0)*math.cos(a) - (y-y0)*math.sin(a);     var v2 = (x-x0)*math.sin(a) + (y-y0)*math.cos(a);     return v1 >= 0 && v1 <= l1 && v2 >= 0 && v2 <= l2; } 

to use it:

var p = {x: /*user longitude*/, y: /*user latitude*/}; var p0 = {x: /*rect longitude*/, y: /*rect latitude*/}; var = /*angle of rect in rad*/; var l1 = /*length of 1 side of rectangle*/ var l2 = /*length of second size*/ isinrectangle(p.x, p.y, p0.x, p0.y, a, l1, l2); // => return true if inside, false otherwise