一种方法是您在要支持的不同浏览器中编写和测试应用程序，而在其中不会存在很多差异(当然有一些差异).现代浏览器.
说您写的页面上有javascript document.all，这在许多浏览器中都无法使用，因此您应该使用document.getElementById().
互联网上有足够的资料可以用来查找所有浏览器支持的脚本和属性.

One way would be you write and test you application in different browsers that you want to support, there wont be to many(ofcourse there are some) differences in modern browser.
say you write a page on which you have javascript document.all, this wont work in many browser and therefore you should be using document.getElementById().
there is good enough material on internet you can use to find script and properties supported by all browsers.