10 Useful Firefox Developer Tools You Should Know

Firefox being “developer’s browser” has many great tools to help make our work easier. You can find more on its tool collection on the Firefox Developer Tools webpage and can also try their Developer Edition Browser which has more features and tools that are being tested.

For this post, I’ve listed 10 handy tools you might like from its developer tools collection. I’ve also demonstrated what these tools can do with GIFs plus how to access them for quick reference.

1. View horizontal and vertical rulers

Firefox tool - ruler

Firefox has a ruler tool that displays both horizontal and vertical rulers with pixel units on the page. The tool is useful for arranging your elements across the page.

To access rulers through the menu:

  1. Go to: ☰ > Developer > Developer Toolbar (shortcut: Shift + F2).
  2. Once the toolbar appears at the bottom of the page, type rulers.
  3. Pess Enter.

To make this appear on the developer tools window:

  1. Go to “Toolbox Options”.
  2. Under the “Available Toolbox Buttons” section, check the “Toggle rulers for the page” checkbox.

2. Take screenshots using CSS selectors

Firefox tool - screenshot

Although the Firefox toolbar lets you take screenshots of the full page or visible portions, in my opinion the CSS selector method is more useful for capturing screenshots of individual elements as well as for elements that are visible on mouse-hover only (like menus).

To take screenshots through the menu:

  1. Go to ☰ > Developer > Developer Toolbar (shortcutShift + F2).
  2. Once the toolbar appears at the bottom of the page, type screenshot --selector any_unique_css_selector.
  3. Press enter.

To make this appear on the developer tools window:

  1. Click “Toolbox Options” and under “Available Toolbox Buttons” section.
  2. Check “Take a fullpage screenshot” checkbox.

3. Pick colors from web pages

Firefox tool - colorpicker

Firefox has a built-in color picker tool by the name of “Eyedropper”.

To access the “Eyedropper” tool through menu go to ☰ > Developer > Eyedropper.

To make this appear on the developer tools window: click “Toolbox Options” and under “Available Toolbox Buttons” section check “Grab a color from the page” checkbox.

4. View page layout in 3D

Firefox tool - 3d view

Viewing webpages in 3D helps with layout problems. You’ll be able to see the different layered elements much more clearly in 3D view. To view the webpage in 3D, click the “3D View” tool button.

To make this appear on the developer tools window, click “Toolbox Options” and under “Available Toolbox Buttons” section check the”3D View” checkbox.

5. View browser style

Firefox tool - browser style

Browser Styles consist of two types: the default style a browser assigns for every element, and the browser-specific styles (the ones with the browser prefix). By taking a look at the browser styles you’ll be able to diagnose any override issues in your stylesheet and also come to know of any existing browser specific styles .

To access “Browser styles” through menu:

  1. Go to ☰ > Developer > Inspector.
  2. Click the “Computed” tab in the right section.
  3. Check the “Browser styles” checkbox.

You can also open the “Inspector” tab through the shortcut Ctrl +Shift + C and then accessing “Browser styles”.

6. Disable JavaScript for current session

Firefox tool - disable JS

For best practice and screen reader compatibility it is always advised to code any website in such a way that its functionality is not hindered in a javascript-disabled environment. To test for such environments, you can disable the JavaScript for the session you’re working in.

To disable JavaScript for current session click “Toolbox Options” and under “Advanced settings” section check the “Disable JavaScript*” checkbox.

7. Hide CSS style from the page

Firefox tool - disable style

Just like JavaScript, due to accessibility concerns it is best to design websites in such a way that the pages should still be readable even without any styles. To see how the page looks without any style, you can disable them in the developer tools.

To remove any CSS style (inline, internal or external) applied on a webpage, just click on the eye symbol of the listed stylesheets in the “Style Editor” tab. Click it again to revert to the original view.

To access “Style Editor” through menu go to ☰ > Developer > Style Editor (shortcut: Shift + F7.

8. Preview the HTML content response to a request

Firefox tool - preview response

Firefox developer tools has an option to preview the HTML content type responses. This helps the developer to preview any 302 redirects and check whether any sensitive information has been rendered or not in the response.

To access “Preview” through menu:

  1. Go to ☰ > Developer > Network (shortcut: Ctrl +Shift + Q.
  2. Open the webpage of your choice or reload the current page, click on the desired request (with HTML response) from the list of requests.
  3. Click the “Preview” tab in the right section.

9. Preview webpage in different screen sizes

Firefox tool - responsive

To test a webpage for its responsiveness use the “Responsive Design View”, which can be accessed by ☰ > Developer > Responsive Design View or with the shortcut: Ctrl +Shift + M.

To make the “Responsive Design Mode” tool button appear, click “Toolbox Options” and under the “Available Toolbox Buttons” section, check “Responsive Design Mode” checkbox.

10. Run JavaScript on pages

Firefox tool - responsive

For quick JavaScript executions on any webpage simply use the “Scratchpad” tool of Firefox. To access “Scratchpad” through the menu go to; ☰ > Developer > Scratchpad or use the keyboard shortcut Shift + F4.

To make the “Scratchpad” tool button appear on the developer tools window for quick use: click “Toolbox Options” and under the “Available Toolbox Buttons” section check the “Scratchpad” checkbox.

The post 10 Useful Firefox Developer Tools You Should Know appeared first on Hongkiat.

Critical zero-day exploit in IE 6, 7, and 8 allows complete takeover

Internet Explorer 8

Internet Explorer 8

Update your browser! On Saturday, Microsoft posted a security advisory that warns that Internet Explorer 6, 7, and 8 are vulnerable to a remote code execution bug. It even notes that an attempt to exploit this bug in IE 8 has already been found in the wild. Luckily, IE 9 and 10 are not affected. If you can update, do so immediately.

Microsoft explains that in its default state, Internet Explorer running on Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2 isn’t vulnerable. Microsoft Outlook, Microsoft Outlook Express, and Windows Mail also don’t appear to be affected, thanks to their increased restriction of JavaScript and ActiveX. If you can’t update to IE 9 or 10 for technical or business reasons, switching to Firefox or Chrome for general surfing will keep you safe from this specific vulnerability.

IE LogoIf updating IE and running a third-party browser aren’t options, there are workarounds. Running and properly configuring Microsoft’s Enhanced Mitigation Experience Toolkit will make the vulnerability more difficult for malicious websites to exploit. Using IE’s Security Zone feature, you can block ActiveX controls and JavaScript from running in the first place by cranking up “internet” and “local intranet” to the high setting. Alternately, you can configure IE to ask before running any scripts. It might be a pain in the neck to surf the web in this mode, but it’s better than being vulnerable to arbitrary code execution.

Microsoft does plan on issuing a patch, but it has yet to set a timeframe for the release. If need be, it will release the patch out of cycle, so that’s at least a little bit of good news for those of us affected by this bug. Internet Explorer is a huge target for black hats, and it’s only a matter of time before the next big vulnerability is found. Microsoft is working hard at making their browser as hardened as possible, but the onus remains on the user to keep out of the line of fire.

Using basic security tools like using Sandboxie while keeping your OS and anti-virus up-to-date will drastically decrease your risk of attack. That’s not enough, though. Clicking links in email and IM as well as browsing untrusted websites is still dangerous despite all of the strides in security we’ve made. Your gut is the first line of defense against security vulnerabilities. Don’t let your guard down just because security software is getting better. There is no magic bullet in security.

Critical zero-day exploit in IE 6, 7, and 8 allows complete takeover

Internet Explorer 8

Update your browser! On Saturday, Microsoft posted a security advisory that warns that Internet Explorer 6, 7, and 8 are vulnerable to a remote code execution bug. It even notes that an attempt to exploit this bug in IE 8 has already been found in the wild. Luckily, IE 9 and 10 are not affected. If you can update, do so immediately.

Microsoft explains that in its default state, Internet Explorer running on Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2 isn’t vulnerable. Microsoft Outlook, Microsoft Outlook Express, and Windows Mail also don’t appear to be affected, thanks to their increased restriction of JavaScript and ActiveX. If you can’t update to IE 9 or 10 for technical or business reasons, switching to Firefox or Chrome for general surfing will keep you safe from this specific vulnerability.

IE LogoIf updating IE and running a third-party browser aren’t options, there are workarounds. Running and properly configuring Microsoft’s Enhanced Mitigation Experience Toolkit will make the vulnerability more difficult for malicious websites to exploit. Using IE’s Security Zone feature, you can block ActiveX controls and JavaScript from running in the first place by cranking up “internet” and “local intranet” to the high setting. Alternately, you can configure IE to ask before running any scripts. It might be a pain in the neck to surf the web in this mode, but it’s better than being vulnerable to arbitrary code execution.

Microsoft does plan on issuing a patch, but it has yet to set a timeframe for the release. If need be, it will release the patch out of cycle, so that’s at least a little bit of good news for those of us affected by this bug. Internet Explorer is a huge target for black hats, and it’s only a matter of time before the next big vulnerability is found. Microsoft is working hard at making their browser as hardened as possible, but the onus remains on the user to keep out of the line of fire.

Using basic security tools like using Sandboxie while keeping your OS and anti-virus up-to-date will drastically decrease your risk of attack. That’s not enough, though. Clicking links in email and IM as well as browsing untrusted websites is still dangerous despite all of the strides in security we’ve made. Your gut is the first line of defense against security vulnerabilities. Don’t let your guard down just because security software is getting better. There is no magic bullet in security.

Critical zero-day exploit in IE 6, 7, and 8 allows complete takeover

Internet Explorer 8

Update your browser! On Saturday, Microsoft posted a security advisory that warns that Internet Explorer 6, 7, and 8 are vulnerable to a remote code execution bug. It even notes that an attempt to exploit this bug in IE 8 has already been found in the wild. Luckily, IE 9 and 10 are not affected. If you can update, do so immediately.

Microsoft explains that in its default state, Internet Explorer running on Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2 isn’t vulnerable. Microsoft Outlook, Microsoft Outlook Express, and Windows Mail also don’t appear to be affected, thanks to their increased restriction of JavaScript and ActiveX. If you can’t update to IE 9 or 10 for technical or business reasons, switching to Firefox or Chrome for general surfing will keep you safe from this specific vulnerability.

IE LogoIf updating IE and running a third-party browser aren’t options, there are workarounds. Running and properly configuring Microsoft’s Enhanced Mitigation Experience Toolkit will make the vulnerability more difficult for malicious websites to exploit. Using IE’s Security Zone feature, you can block ActiveX controls and JavaScript from running in the first place by cranking up “internet” and “local intranet” to the high setting. Alternately, you can configure IE to ask before running any scripts. It might be a pain in the neck to surf the web in this mode, but it’s better than being vulnerable to arbitrary code execution.

Microsoft does plan on issuing a patch, but it has yet to set a timeframe for the release. If need be, it will release the patch out of cycle, so that’s at least a little bit of good news for those of us affected by this bug. Internet Explorer is a huge target for black hats, and it’s only a matter of time before the next big vulnerability is found. Microsoft is working hard at making their browser as hardened as possible, but the onus remains on the user to keep out of the line of fire.

Using basic security tools like using Sandboxie while keeping your OS and anti-virus up-to-date will drastically decrease your risk of attack. That’s not enough, though. Clicking links in email and IM as well as browsing untrusted websites is still dangerous despite all of the strides in security we’ve made. Your gut is the first line of defense against security vulnerabilities. Don’t let your guard down just because security software is getting better. There is no magic bullet in security.