JavaScript Calculator Project Feedback Please

I’d like feedback on my JavaScript calculator please.

I used github rather than codepen. You can see the working calculator here:

You can view the code in github:

I made the choice to write only in JavaScript, using onclick event handlers, without relying on jQuery. Because of my choice to display multiple mathematical operations, I ran into problems where a user could enter multiple decimal points, which then crashed the app when you sum the result. I solved that problem by creating a “hasDecimal” flag to keep track if a particular chunk already has a decimal.

For the display layer, I decided to base my aesthetic on the whimsical Lisa Frank stationary that was popular in the 90s. I wanted to rebel from the restrained colors and plain aesthetic of Bootstrap, and to do something juvenile instead. I imagine this calculator as something you might have embedded in your imaginary Lisa Frank Trapper Keeper, accompanied by rainbow unicorn and dolphin stickers.