Well, you can use Vector3.equals() if you want to check for equality. However, if you need more flexibility because of floating point inaccuracies, you can monkey-path Vector3 with your own equals method like so:
equals( v, epsilon = Number.EPSILON ) {
return ( ( Math.abs( v.x - this.x ) < epsilon ) && ( Math.abs( v.y - this.y ) < epsilon ) && ( Math.abs( v.z - this.z ) < epsilon ) );
}