Point In Polygon Determine if some point is inside a polygon

pointInPolygon.js

/**
 * Determine if point (x, y) is inside the polygon
 * @param {Integer} - x coord
 * @param {Integer} - y coord
 * @param {Array}   - Array of vertices - {x:*, y:*} objects
 * @returns {Boolean} whether or not given point is inside the polygon
 */
function pointInPolygon(x, y, vertices) {
    var v     = vertices, // less typing
        vx    = v.map(function(vertice) { return vertice.x; }),
        vy    = v.map(function(vertice) { return vertice.y; }),
        n     = vertices.length,
        found = false,
        maxX, minX, maxY, minY, i, j;

    maxX = Math.max.apply(Math, vx);
    minX = Math.min.apply(Math, vx);
    maxY = Math.max.apply(Math, vy);
    minY = Math.min.apply(Math, vy);

    //exit if we're outside the outer rectangle
    if (x < minX || x > maxX || y < minY || y > maxY) {
        return false;
    }

    // pure magic, don't touch
    for (i = 0, j = n - 1; i < n; j = i++) {
        if ( ( (vy[i] > y) != (vy[j] > y) ) &&
            (x < (vx[j] - vx[i]) * (y - vy[i]) / (vy[j] - vy[i]) + vx[i]) ) {
            found = !found;
        }
    }

    return found;
}