How to read/write the content from local file?

Developers: Plugin & API
1

Dears,
for the plugin, https://github.com/lynchjames/obsidian-day-planner/releases/download/0.5.8/main.js, I want to read the local template file to the content, how to do it? thanks in advance.

Replace below:
const DAY_PLANNER_DEFAULT_CONTENT = `## Day Planner

  • [ ] `;
    To:
    const DAY_PLANNER_DEFAULT_CONTENT = ??? //read local file