JavaScript 2D Vector Math Library - http://www.cgrats.com/javascript-2d-vector-library.html

Vec2.js

/*
Common vector operations
Author: Tudor Nita | cgrats.com
Version: 0.51

*/
function Vec2(x_,y_)
{
this.x = x_;
this.y = y_;

/* vector * scalar */
this.mulS = function (value){ return new Vec2(this.x*value, this.y*value); }
/* vector * vector */
this.mulV = function(vec_) { return new Vec2(this.x * vec_.x, this.y * vec_.y); }
/* vector / scalar */
this.divS = function(value) { return new Vec2(this.x/value,this.y/value); }
/* vector + scalar */
this.addS = function(value) { return new Vec2(this.x+value,this.y+value); }
/* vector + vector */
this.addV = function(vec_) { return new Vec2(this.x+vec_.x,this.y+vec_.y); }
/* vector - scalar */
this.subS = function(value) { return new Vec2(this.x-value, this.y-value); }
/* vector - vector */
this.subV = function(vec_) { return new Vec2(this.x-vec_.x,this.y-vec_.y); }
/* vector absolute */
this.abs = function() { return new Vec2(Math.abs(this.x),Math.abs(this.y)); }
/* dot product */
this.dot = function(vec_) { return (this.x*vec_.x+this.y*vec_.y); }
/* vector length */
this.length = function() { return Math.sqrt(this.dot(this)); }
/* vector length, squared */
this.lengthSqr = function() { return this.dot(this); }
/*
vector linear interpolation
interpolate between two vectors.
value should be in 0.0f - 1.0f space
*/
this.lerp = function(vec_, value) {
return new Vec2(
this.x+(vec_.x-this.x)*value,
this.y+(vec_.y-this.y)*value
);
}
/* normalize THIS vector */
this.normalize = function() {
var vlen = this.length();
this.x = this.x/ vlen;
this.y = this.y/ vlen;
}
}