How/Tools to Diagnose if the html, javascript or CSS is causing your page to not render?

I am a new web developer and I was wondering if there is any hints as to whether your webpage is not being rendered properly 开发者_如何学运维due to issues related to JavaScript, HTML or CSS. And what tools to possibly use.

Firebug is a great plugin for Firefox that you cannot live without. It will help you troubleshoot those layout issues.

Tools such as BrowserCam or Adobe's Browser Lab can be invaluable for cross browser testing, some cost may apply.

Also it's reasonable for a developer to have a copy of each major browser installed for your own testing, to certainly cover the majority of web users.

A good starting point might be to use W3C Markup & CSS Validation Service which is is a validator by the World Wide Web Consortium (W3C) that allows Internet users to check HTML documents for conformance to HTML or XHTML standards

W3C Wikipedia

The W3C Markup Validation Service

The W3C CSS validation Service

To troubleshoot javascript here is a thread that suggests some useful tools for IE and firefox Javascript troubleshooting tools

A lot of people use firebug. It'll show you javascript errors and let you look inside page's html and styles.

But generally, I'm not sure what "issues related to JavaScript, HTML or CSS" means. Browser has very few ways to know that page renders not as you expect it to (javascript errors being one of them).

I'm a fan of both the aforementioned firebug and web developer plugins in Firefox. The dev tools in Chrome are great as well.

In the end, much of it is experience from seeing and fixing the errors yourself, and that just comes with time.