123456789101112131415161718192021222324<!DOCTYPE html>charset="utf-8"W3Cschool教程(w3cschool.cn)id="demo"单击按钮获取不同类型值的绝对值onclick="myFunction()"点我function myFunction(){var a=Math.abs(7.25);var b=Math.abs(-7.25);var c=Math.abs(null);var d=Math.abs("Hello");var e=Math.abs(2+3);var x=document.getElementById("demo");x.innerHTML=a + "<br>" + b + "<br>" + c + "<br>" + d + "<br>" + e;}