KShapeJS library to extend features of konva JS framework

kshapejs.js

/*
 * Author:      Asif Ahmed
 * Site:        quickgrid.blogspot.com
 * Description: kshapejs is a simple javascript library based on konvajs.
 *              It allow creating some basic shapes not defined in konva
 *              library.
 */

(function(window){
    'use strict';
    function define_library(){
        var kshapejs = {};

        // Takes x,y coordinates of triangle which is left top most point and the triangle size, stroke width
        kshapejs.drawTriangle = function(tx, ty, trisize, tstrokewidth){

            var triangle = [ tx, ty, tx, ty + trisize, tx + trisize, ty + trisize / 2 ];

            var poly = new Konva.Line({
              points: triangle,
              stroke: 'black',
              strokeWidth: tstrokewidth,
              closed : true
            });

            return poly;
        }
        return kshapejs;
    }


    //define globally if it doesn't already exist
    if(typeof(kshapejs) === 'undefined'){
        window.kshapejs = define_library();
    }
    else{
        console.log("kshapejs already defined.");
    }
})(window);