Vector for 2d space

Vector.js

/**
 * A vector for 2d space.
 * @param {integer} x - Center x coordinate.
 * @param {integer} y - Center y coordinate.
 * @param {integer} dx - Change in x.
 * @param {integer} dy - Change in y.
 */
function Vector(x, y, dx, dy) {
    // position
    this.x = x || 0;
    this.y = y || 0;
    // direction
    this.dx = dx || 0;
    this.dy = dy || 0;
}
/**
 * Advance the vectors position by dx,dy
 */
Vector.prototype.advance = function () {
    this.x += this.dx;
    this.y += this.dy;
};
/**
 * Get the minimum distance between two vectors
 * @param {Vector}
 * @return minDist
 */
Vector.prototype.minDist = function (vec) {
    var minDist = Infinity;
    var max = Math.max(Math.abs(this.dx), Math.abs(this.dy),
        Math.abs(vec.dx), Math.abs(vec.dy));
    var slice = 1 / max;
    var x, y, distSquared;
    // get the middle of each vector
    var vec1 = {}, vec2 = {};
    vec1.x = this.x + this.width / 2;
    vec1.y = this.y + this.height / 2;
    vec2.x = vec.x + vec.width / 2;
    vec2.y = vec.y + vec.height / 2;
    for (var percent = 0; percent < 1; percent += slice) {
        x = (vec1.x + this.dx * percent) - (vec2.x + vec.dx * percent);
        y = (vec1.y + this.dy * percent) - (vec2.y + vec.dy * percent);
        distSquared = x * x + y * y;

        minDist = Math.min(minDist, distSquared);
    }

    return Math.sqrt(minDist);
};