I agree that the equal function on the vector prototype is the best solution. Note that you can also build other infix-like operators via chaining.
function Vector(x, y, z) {
this.x = x;
this.y = y;
this.z = z;
}
Vector.prototype.add = function (v2) {
var v = new Vector(this.x + v2.x,
this.y + v2.y,
this.z + v2.z);
return v;
}
Vector.prototype.equal = function (v2) {
return this.x == v2.x && this.y == v2.y && this.z == v2.z;
}
You can see online sample here.
Update: Here’s a more extensive sample of creating a Factory function that supports chaining.