This Vector2 class is probably not the fastest around, but is very easy in use. For example for quick prototyping of games. For a high performance alternative that can do many calculations in for example a render loop, I'd like to redirect you to the awesome gl-matrix by toji.

• length()
• lerp( vec2, factor )
• dot( vec2 )
• normalize()
• cross( vec2 )
• rotate( deg )
• add( vec2|number )
• sub( vec2|number )
• mul( vec2|number )
• div( vec2|number )
• abs()
• equals( vec2 )