如何获取在css样式规则或html标记样式中设置的样式宽度值。

var element = document.getElementById("yourElementId");
var style = window.getComputedStyle(element);
var width = style.getPropertyValue("width");
console.log(width);

var width = $("#yourElementId").css("width");
console.log(width);

var element = document.getElementById("yourElementId");
var width = getComputedStyle(element).getPropertyValue("--width");
console.log(width);