Draw a rectangle with pixi.js

You can’t render geometry (Pixi.Rectangle), they are meant for calculations only. You can do the following instead:

var graphics = new PIXI.Graphics();

graphics.beginFill(0xFFFF00);

// set the line style to have a width of 5 and set the color to red
graphics.lineStyle(5, 0xFF0000);

// draw a rectangle
graphics.drawRect(0, 0, 300, 200);

stage.addChild(graphics);

^source