Object.assign is polyfilled: https://github.com/morris/vanilla-todo/blob/9a27e850e15fddfe0e9504660f516d51d31e5284/public/index.html#L29 https://github.com/morri

Object.assign is polyfilled: https://github.com/morris/vanilla-todo/blob/9a27e850e15fddfe0e9504660f516d51d31e5284/public/index.html#L29 https://github.com/morris/vanilla-todo/blob/9a27e850e15fddfe... That being said, the page still didn't load properly for me when I actually tried it in IE11, but it's not because of Object.assign. Nobody writes ES5 because they want to; many developers are still forced to support Internet Explorer for one reason or another.