toc.js

let repeatSpace = (n, ret = "") => {
    while(--n >0) ret += "　"; return ret;
}
window.onload = ()=>{
    document.querySelectorAll("h1, h2, h3, h4").forEach((value)=> {
        document.getElementById("sidebar_toc").innerHTML += 
        `${repeatSpace(value.tagName.substring(1))}<a href="#${value.id}">${value.innerHTML}</a><br>`;
    })
}