JSFiddle - React, Tailwind, and code Playground

JavaScript

localStorage.knol = '{}';

// my new information
var data = {character: "中", totalMistakes: 0};
var han  = data.character;

// unpack, update, repackage knol
var knol = JSON.parse(localStorage.knol)
knol[han] = data;
localStorage.knol = JSON.stringify(knol);

// Print to check if all went well.
console.log('data: ',data)
console.log('han: ',han)
console.log('knol: ',knol)
console.log('localStorage.knol: ',localStorage.knol)
console.log('localStorage.knol: ',JSON.parse(localStorage.knol))
console.log('localStorage.knol[han]: ',JSON.parse(localStorage.knol)[han])