如何从JS字符串设置文本样式

var text = "<b>加粗文本</b>，<i>斜体文本</i>，<u>下划线文本</u>";
document.getElementById("myElement").innerHTML = text;

var text = "设置文本样式";
var styledText = "<span style='font-weight: bold; color: red; font-size: 20px; text-align: center;'>" + text + "</span>";
document.getElementById("myElement").innerHTML = styledText;

var text = "设置文本样式";
var styledText = $("<span>").text(text).css({"font-weight": "bold", "color": "red", "font-size": "20px", "text-align": "center"});
$("#myElement").append(styledText);