document.addEventListener("DOMContentLoaded", () => { var head = document.querySelector("head"); var newcss; let cssbtn1 = document.getElementById("css1"); let cssbtn2 = document.getElementById("css2"); let cssbtn3 = document.getElementById("css3"); let cssbtn4 = document.getElementById("css4"); let cssbtn5 = document.getElementById("css5"); cssbtn1.addEventListener("click", (e) => { if (newcss) return; newcss = document.createElement("link"); newcss.rel = "stylesheet"; newcss.href = "new2.css"; head.appendChild(newcss); // link要素を追加 }); cssbtn2.addEventListener("click", (e) => { if (newcss) return; newcss = document.createElement("link"); newcss.rel = "stylesheet"; newcss.href = "new3.css"; head.appendChild(newcss); // link要素を追加 }); cssbtn3.addEventListener("click", (e) => { if (newcss) return; newcss = document.createElement("link"); newcss.rel = "stylesheet"; // ※newcss.title = "あとから版"; // title属性入れると代替CSSに newcss.href = "new4.css"; head.appendChild(newcss); // link要素を追加 }); cssbtn4.addEventListener("click", (e) => { if (newcss) return; newcss = document.createElement("link"); newcss.rel = "stylesheet"; newcss.href = "new5.css"; head.appendChild(newcss); // link要素を追加 }); cssbtn5.addEventListener("click", (e) => { if (newcss) return; newcss = document.createElement("link"); newcss.rel = "stylesheet"; newcss.href = "new6.css"; head.appendChild(newcss); // link要素を追加 }); let unlbtn = document.getElementById("unl"); unlbtn.addEventListener("click", (e) => { if (newcss) { newcss.remove(); newcss = null; } }); });