背景色のようなJSのアラートスタイルを変更する方法

次のようにコードコードをコピーします。

window.alert = function（str）

{{

var shield = document.createelement（ "div"）;

shield.id = "shield";

shield.style.position = "absolute";

shield.style.left = "0px";

shield.style.top = "0px";

shield.style.width = "100％";

shield.style.height = document.body.scrollheight+"px";

//ダイアログボックスがポップアップするときの背景色

shield.style.background = "#fff";

shield.style.textalign = "center";

shield.style.zindex = "25";

//バックグラウンド透過IEは有効です

//shield.style.filter = "alpha（ofacity = 0）";

var alertfram = document.createelement（ "div"）;

alertfram.id = "alertfram";

alertfram.style.position = "absolute";

alertfram.style.left = "50％";

alertfram.style.top = "50％";

alertfram.style.marginleft = "-225px";

alertfram.style.margintop = "-75px";

alertfram.style.width = "450px";

alertfram.style.height = "150px";

alertfram.style.background = "＃ff0000";

alertfram.style.textalign = "center";

alertfram.style.lineheight = "150px";

alertfram.style.zindex = "300";

strhtml = "<ul style =/"

strhtml = "li style =/"＃dd828d-20px; 1PX SOLID＃F9CADE;/"> [カスタムプロンプト] </li>/n";

strhtml = "<li style =/" #fff; /">"+str+"</li>/n";

strhtml = "<li style =/" /"button/" value =/"ok/" onclick =/"dook（）/"/> </li>/n ";

strhtml += "</ul>/n";

alertfram.innerhtml = strhtml;

document.body.appendChild（alertfram）;

document.body.AppendChild（Shield）;

var adj = setinterval（ "doalpha（）"、5）;

this.dook = function（）{

alertfram.style.display = "none";

Shield.display = "none";

}

alertfram.focus（）;

document.body.onselectstart = function（）{return false;};

}

効果は図に示されているとおりです