codepen fold unfold JavaScript code panel

/*
  add panel with fold/unfold button at top-left
  inject with custom-javascript-for-web chrome plugin
  ( https://chrome.google.com/webstore/detail/custom-javascript-for-web/poakhlngfciodnhlhhgnaaelnpjljija )
*/
~function(){

if(window.pluginFold){
    try{
    document.body.removeChild(window.pluginFold.panel);
    }catch(e){console.error(e);}
}

let p = window.pluginFold = {
    setFold(fold){
        let cm = document.querySelectorAll(".CodeMirror")[2].CodeMirror;
        cm.operation(()=>{
            for (var l = cm.firstLine(); l <= cm.lastLine(); ++l) 
                cm.foldCode({line: l, ch: 0}, null, fold ? "fold" : "unfold");
        })
    },
};

p.panel = document.createElement("div");
p.panel.style.position = "absolute";
p.panel.style.left = "150px";
p.panel.style.top = "0px";
p.panel.className = "plugin-fold-panel";
//p.panel.style.border = "2px solid red";
//p.panel.style.width = "128px";
//p.panel.style.height = "128px";
p.panel.style.zIndex = 100;

let btn;

btn = document.createElement("button");
btn.textContent = "fold";
btn.onclick = e=>p.setFold(true);
p.panel.appendChild(btn);

btn = document.createElement("button");
btn.textContent = "unfold";
btn.onclick = e=>p.setFold(false);
p.panel.appendChild(btn);

document.body.appendChild(p.panel);

}();