How to set and get custom attributes in js

Js method to operate custom attributes:

var testEle = document.getElementByIdx_x("test")
 
testEle.setAttribute("test","aaa"); // 设置
testEle.getAttribute("test")； //获取
testEle.attributes["test"].nodeValue; // 获取

Jquery method to operate custom attributes:

$("#test").attr("test","aaa") // 设置
$("#test").removeAttr("test") // 删除
  
var testAttr = "ddd";
$('#test[test="'+ testAttr +'"]')