<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>JS中的运算</title> <script> window.onload = function () { var num = 12345; /* num表示的时间单位是秒, 现在转换成多少分钟多少秒的格式显示 */ function aaa() { alert(parseInt(num / 60) + "分" + (num % 60) + "秒"); } aaa();// 调用函数, 则执行函数中的代码. /* 下面的函数用来演示隔行显示效果 */ function bbb() { var divs = document.getElementsByTagName('div'); for (let i = 0; i < divs.length; i++) { if (i % 2 == 0) { divs[i].style.background = 'gray'; } else { divs[i].style.background = 'green'; } // divs[i].style.background = i % 2 == 0 ? 'gray' : 'green'; } } bbb(); } </script> </head> <body> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> <div>6</div> <div>7</div> <div>8</div> </body> </html>