Box2d JavaScript Basic Sample

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I have seen a lot of sample but didn't found the basic code of Box2d in Javascript. So i think i should put this in blog to help others.

This display is here


and code is
<script>
function init() {
var completeScaleRatio = 30;
var canvasWd = document.getElementById("canvas").width;
var canvasHt = document.getElementById("canvas").height;
         var   b2Vec2 = Box2D.Common.Math.b2Vec2
            ,  b2AABB = Box2D.Collision.b2AABB
          , b2BodyDef = Box2D.Dynamics.b2BodyDef
          , b2Body = Box2D.Dynamics.b2Body
          , b2FixtureDef = Box2D.Dynamics.b2FixtureDef
          , b2Fixture = Box2D.Dynamics.b2Fixture
          , b2World = Box2D.Dynamics.b2World
          , b2MassData = Box2D.Collision.Shapes.b2MassData
          , b2PolygonShape = Box2D.Collision.Shapes.b2PolygonShape
          , b2CircleShape = Box2D.Collision.Shapes.b2CircleShape
          , b2DebugDraw = Box2D.Dynamics.b2DebugDraw
            ,  b2MouseJointDef =  Box2D.Dynamics.Joints.b2MouseJointDef
            ;
         
         var world = new b2World(
               new b2Vec2(0, 10)
            ,  true
         );
 
 var fixDef = new b2FixtureDef;
         fixDef.density = 1.0;
         fixDef.friction = 0.5;
         fixDef.restitution = .2;
         
         var bodyDef = new b2BodyDef;
         
         //create ground
         bodyDef.type = b2Body.b2_staticBody;
 fixDef.shape = new b2PolygonShape;
 //Bottom
 bodyDef.position.Set(10, canvasHt / completeScaleRatio-.1);
 fixDef.shape.SetAsBox(20, .1);
 world.CreateBody(bodyDef).CreateFixture(fixDef);
 //Top
 bodyDef.position.Set(10, .1);
 world.CreateBody(bodyDef).CreateFixture(fixDef);
 //Left
 bodyDef.position.Set(.1, 0);
 fixDef.shape.SetAsBox(.1, 14);
 world.CreateBody(bodyDef).CreateFixture(fixDef);
 //Right
 bodyDef.position.Set(canvasWd/completeScaleRatio-.1, 0);
 world.CreateBody(bodyDef).CreateFixture(fixDef);
 
 //Create Bodies
 bodyDef.type = b2Body.b2_dynamicBody;
 var carShape = new b2PolygonShape();
 var vertix = new Array(new b2Vec2(0, 0), new b2Vec2(.5, -2), new b2Vec2(1, 3), new b2Vec2(.7, 3), new b2Vec2(0, 1));
 carShape.SetAsArray(vertix);
 fixDef.shape = carShape
 bodyDef.position.Set(5, canvasHt / completeScaleRatio/2);
 world.CreateBody(bodyDef).CreateFixture(fixDef);
 
 var debugDraw = new b2DebugDraw();
debugDraw.SetSprite(document.getElementById("canvas").getContext("2d"));
debugDraw.SetDrawScale(completeScaleRatio);
debugDraw.SetFillAlpha(1);
debugDraw.SetLineThickness(1.0);
debugDraw.SetFlags(b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit);
world.SetDebugDraw(debugDraw);

window.setInterval(update, 1000 / 60);
function update() {
   world.Step(1/60 , 10, 10);//Gravity Animation is caused by this.
            world.DrawDebugData(); // If removed then no bas Area will be shown
            world.ClearForces();
}
</script>