I have this simple function to set an angle for a vector. It effectively gets the vector's current magnitude (length), calulates the angle and converts the angle from radians to degrees. Then I apply the angle to X and Y, lastly multiplying the vector by it's original magnitude.

this.setAngle = function(degree){

    var l = this.length();  //magnitude of vector

    var angle = degree*Math.PI/180; //degress converted to radians

    this.x=Math.cos(angle);

    this.y=Math.sin(angle);

    this.multiply(l);  //original magnitude

    return;

}

However I am unsure how to obtain (get) an angle from a Vector. Below is my attempt:

this.getAngle = function(){

    var angle = Math.atan(this.y/this.x);   //radians

    var degrees = angle/(180*Math.PI);  //degrees

    return Math.floor(degrees); //round number, avoid decimal fragments

}

This attempt doesn't return any value except 0 or -1.

Any suggestions?

Edit:

Correct method:

this.getAngle = function(){

    var angle = Math.atan2(this.y, this.x);

    var degrees = 180 * angle / Math.PI;

    return (360 + Math.round(degrees)) % 360;

}