What is Messenger Preview?

Messenger Preview is a Chrome extension developed by Jared Hughes, and its main feature is "Preview the appearance of messages sent in Facebook Messenger. Know how bold, italics, strikethrough, code, and math will appear.".

Extension Screenshots

Download Messenger Preview Extension CRX File

Download Messenger Preview extension files in crx format, manually install Chrome extensions in the browser, or share the crx files with friends to easily install Chrome extensions.

Extension Usage Instructions

▶ Update:

This extension no longer works as of December 16th, 2020. Messenger made extensive changes to their user interface, including disabling KaTeX. Since the KaTeX preview was my main motivation for making this, I have no intentions to fix this extension.

However, the number of users has tripled (~30 to 100) since it broke, so I'm leaving this published on the off-chance that it still works for some people.

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Messenger has many different formatting options, such as bold, italics, strikethrough, monospaced code, and math formatting through KaTeX (a subset of LaTeX). It can be hard to know what a message will look like without sending it once, so this extension shows a preview of how each message will appear before you send it.

Note: the formatting only renders properly on web Messenger. Mobile Messenger does not show any of the formatting.

All previews are performed client-side. None of your information is sent to any third-party server.

See https://www.facebook.com/help/147348452522644 for details on formatting text.

Supported functions in the LaTeX math formatting are at https://www.facebook.com/help/147348452522644.

▶ Usage

Write messages as normal. As you type, you should see a light message appear about where it will appear when you send the message (when it actually sends, your message might attach to the group above it). Sometimes, the preview is a bit hidden, requiring you to scroll down within the chat.

Warning: Sometimes the preview does not show at first. Reload the messenger page once, and it should appear at least until you open another conversation. Reloading the page does *not* delete the contents of the message box.

As usual in Messenger chats, write

• *bold*
• _italics_
• ~strikethrough~
• $ $$ to display inline math using LaTeX, e.g. `$\frac{1}{2}$`
• \[\] to display math that takes up the whole message. This may include
scrollbars and is useful for long chunks of math.
• `inline code`
• ```full message code```
• for code with syntax highlighting, use

```python
def f(a,b):
return a + b
```

If necessary, press ctrl+enter to create a newline within a message.

The math uses a subset of KaTeX, which is itself a subset of LaTeX. See the
[Katex Docs](https://katex.org/docs/supported.html) for supported functions.
Some functions only work within math that takes up the whole message
(`\[...\]`). If anything at all is wrong, none of the message will render as
math.

Clicking the three dots to the left of a message then "Show Original" will
remove all formatting from the message.

▶ Limitations
This is an unofficial extension; Facebook might change Messenger at any time which could break this extension.

The extension only works in www.messenger.com and www.facebook.com/messenger, not the preview within www.facebook.com.$

Extension Basic Information

Name	Messenger Preview
ID	cpimjhhigdjabaeklhlehfaghfeacibn
Official URL	https://chrome.google.com/webstore/detail/messenger-preview/cpimjhhigdjabaeklhlehfaghfeacibn
Description	Preview the appearance of messages sent in Facebook Messenger. Know how bold, italics, strikethrough, code, and math will appear.
File Size	12.63 KB
Installation Count	126
Current Version	0.1
Last Updated	2021-04-02
Publish Date	2019-12-24
Rating	5.00/5 Total 3 Ratings
Developer	Jared Hughes
Email	[email protected]
Payment Type	free
Supported Languages	en
manifest.json
{ "update_url": "https:\/\/clients2.google.com\/service\/update2\/crx", "name": "Messenger Preview", "version": "0.1", "description": "Preview the appearance of messages sent in Facebook Messenger. Know how bold, italics, strikethrough, code, and math will appear.", "permissions": [ ":\/\/www.messenger.com\/", ":\/\/www.facebook.com\/messages\/*" ], "icons": { "128": "images\/icon128.png" }, "content_scripts": [ { "matches": [ ":\/\/www.messenger.com\/t\/", ":\/\/www.facebook.com\/messages\/**" ], "js": [ "content.js" ] } ], "web_accessible_resources": [ "script.js" ], "manifest_version": 2 }

Messenger Preview

What is Messenger Preview?

Extension Screenshots

Download Messenger Preview Extension CRX File

Extension Usage Instructions

Extension Basic Information

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