This is just a file that contains my MyHelper class, in which I add useful classes and function that I need to use often when working with js.

myhelper.js

/* Myhelper */
var MyHelper = {}

MyHelper.getValueOfPixelString = function(string) {
  if(string.indexOf("px") > -1) {
    res = Number(string.replace("px",""));
    if(res) return res;
    else {
      console.log('ERROR in MyHelper.getValueOfPixelString():'
         + ' replacing "px" in passed string "' + string + '" did not return a'
        + ' number');
    }
  }
  else {
    console.log('ERROR in MyHelper.getValueOfPixelString():'
      + 'no string "px" found in passed string "' + string + '"');
    return false;
  }
}

MyHelper.Vector2 = function(x,y) {
  this.x = x;
  this.y = y;
}

MyHelper.Vector2.prototype.getLength = function() {
  return Math.sqrt(Math.pow(this.x,2) + Math.pow(this.y,2));
}

MyHelper.Vector2.prototype.getVectorTo = function(vector) {
  return this.getSubstracted(vector);
}

MyHelper.Vector2.prototype.getDistanceTo = function(vector) {
  return this.getVectorTo(vector).getLength();
}

MyHelper.Vector2.prototype.getNormalized = function() {
  return new MyHelper.Vector2(
    this.x/this.getLength(),
    this.y/this.getLength()
  )
}

MyHelper.Vector2.prototype.normalize = function() {
  var norm = this.getNormalized();
  this.x = norm.x;
  this.y = norm.y;
}

MyHelper.Vector2.prototype.getAdded = function(vector) {
  return new MyHelper.Vector2(this.x + vector.x, this.y + vector.y);
}

MyHelper.Vector2.prototype.add = function (vector) {
  this.x += vector.x;
  this.y += vector.y;
}

MyHelper.Vector2.prototype.getSubstracted = function (vector) {
  return new MyHelper.Vector2(this.x - vector.x, this.y - vector.y);
}

MyHelper.Vector2.prototype.substract = function (vector) {
  this.x -= vector.x;
  this.y -= vector.y;
}

MyHelper.Vector2.prototype.getMultiplied = function (number) {
  return new MyHelper.Vector2(this.x*number, this.y*number);
}

MyHelper.Vector2.prototype.multiply = function (number) {
  this.x *= number;
  this.y *= number;
}


MyHelper.absToRelPosition = function(x,y,elem) {
  return new MyHelper.Vector2(
    x-elem.position().left,
    y-elem.position().top
  );
}