Good catch. It's because the initial value for year is: var year = new Date().getFullYear(); and 2022 is outside of the range of the slider. If you tweak

Good catch. It's because the initial value for year is: var year = new Date().getFullYear(); and 2022 is outside of the range of the slider. If you tweak the HTML to change the slider's max value to 2022, then it works properly.