JPS is fun; though I struggled to interpret the suggested performance gains by the authors indeed due to the calculation of the jump nodes.
Many years ago I added a visualisation to the JPS implementation of PathFinding.js to visualise this recursive search to find jump nodes - here's an online demo: https://qiao.github.io/PathFinding.js/visual/
Many years ago I added a visualisation to the JPS implementation of PathFinding.js to visualise this recursive search to find jump nodes - here's an online demo: https://qiao.github.io/PathFinding.js/visual/