How do I render a Word document (.doc, .docx) in the browser using JavaScript?

The answers by Brandon and fatbotdesigns are both correct, but having implemented the Google docs preview, we found multiple .docx files that couldn't be handled by Google. Switched to the MS Office Online preview and works likes a charm.

My recommendation would be to use the MS Office Preview URL over Google's.

https://view.officeapps.live.com/op/embed.aspx?src=http://remote.url.tld/path/to/document.doc' 

No browsers currently have the code necessary to render Word Documents, and as far as I know, there are no client-side libraries that currently exist for rendering them either.

However, if you only need to display the Word Document, but don't need to edit it, you can use Google Documents' Viewer via an <iframe> to display a remotely hosted .doc/.docx.

<iframe src="https://docs.google.com/gview?url=http://remote.url.tld/path/to/document.doc&embedded=true"></iframe>

Solution adapted from "How to display a word document using fancybox".

Example:

JSFiddle

However, if you'd rather have native support, in most, if not all browsers, I'd recommend resaving the .doc/.docx as a PDF file Those can also be independently rendered using PDF.js by Mozilla.

Edit:

Huge thanks to cubeguerrero for posting the Microsoft Office 365 viewer in the comments.

<iframe src='https://view.officeapps.live.com/op/embed.aspx?src=http://remote.url.tld/path/to/document.doc' width='1366px' height='623px' frameborder='0'>This is an embedded <a target='_blank' href='http://office.com'>Microsoft Office</a> document, powered by <a target='_blank' href='http://office.com/webapps'>Office Online</a>.</iframe>

One more important caveat to keep in mind, as pointed out by lightswitch05, is that this will upload your document to a third-party server. If this is unacceptable, then this method of display isn't the proper course of action.

Live Examples:

Google Docs Viewer

Microsoft Office Viewer