Log messages in the Console
This interactive tutorial shows you how to log and filter messages in the Chrome DevTools Console.
Figure 1. Messages in the Console.
Set up the demo and DevTools #
This tutorial is designed so that you can open up the demo and try all the workflows yourself. When you physically follow along, you're more likely to remember the workflows later.
Open the demo.
Optional: Move the demo to a separate window.
Figure 2. This tutorial on the left, and the demo on the right.
Focus the demo and then press Control+Shift+J or Command+Option+J (Mac) to open DevTools. By default DevTools opens to the right of the demo.
Figure 3. DevTools opens to the right of the demo.
Figure 4. DevTools docked to the bottom of the demo.
Figure 5. DevTools undocked in a separate window.
Click the Log Info button in the demo.
Hello, Console!gets logged to the Console.
Figure 6. The Console after clicking Log Info.
Next to the
Figure 7. DevTools opens the Sources panel after you click log.js:2.
Navigate back to the Console using any of the following workflows:
- Click the Console tab.
- Press Control+[ or Command+[ (Mac) until the Console panel is in focus.
- Open the Command Menu, start typing
Console, select the Show Console Panel command, and then press Enter.
Click the Log Warning button in the demo.
Abandon Hope All Ye Who Entergets logged to the Console. Messages formatted like this are warnings.
Figure 8. The Console after clicking Log Warning.
Optional: Click log.js:12 to view the code that caused the message to get formatted like this, and then navigate back to Console when you're finished. Do this whenever you want to see the code that caused a message to get logged a certain way.
Click the Expand icon in front of
Abandon Hope All Ye Who Enter. DevTools shows the stack trace leading up to the call.
Figure 9. A stack trace.
The stack trace is telling you that a function named
logWarningwas called, which in turn called a function named
quoteDante. In other words, the call that happened first is at the bottom of the stack trace. You can log stack traces at any time by calling
Click Log Error. The following error message gets logged:
I'm sorry, Dave. I'm afraid I can't do that.
Figure 10. An error message.
Click Log Table. A table about famous artists gets logged to the Console. Note how the
birthdaycolumn is only populated for one row. Check the code to figure out why that is.
Figure 11. A table in the Console.
Click Log Group. The names of 4 famous, crime-fighting turtles are grouped under the
Adolescent Irradiated Espionage Tortoiseslabel.
Figure 12. A group of messages in the Console.
Click Log Custom. A message with a red border and blue background gets logged to the Console.
Figure 13. A message with custom formatting in the Console.
console methods. Each method formats messages differently.
There are even more methods than what has been demonstrated in this section. At the end of the tutorial you'll learn how to explore the rest of the methods.
View messages logged by the browser #
The browser logs messages to the Console, too. This usually happens when there's a problem with the page.
Click Cause 404. The browser logs a
Figure 14. A 404 error in the Console.
Click Cause Error. The browser logs an uncaught
Figure 15. A TypeError in the Console.
Click the Log Levels dropdown and enable the Verbose option if it's disabled. You'll learn more about filtering in the next section. You need to do this to make sure that the next message you log is visible. Note: If the Default Levels dropdown is disabled, you may need to close the Console Sidebar. Filter by Message Source below for more information about the Console Sidebar.
Figure 16. Enabling the Verbose log level.
Click Cause Violation. The page becomes unresponsive for a few seconds and then the browser logs the message
[Violation] 'click' handler took 3000msto the Console. The exact duration may vary.
Figure 17. A violation in the Console.
Filter messages #
On some pages you'll see the Console get flooded with messages. DevTools provides many different ways to filter out messages that aren't relevant to the task at hand.
Filter by log level #
console method is assigned a severity level:
Error. For example,
console.log() is an
Info-level message, whereas
console.error() is an
Click the Log Levels dropdown and disable Errors. A level is disabled when there is no longer a checkmark next to it. The
Error-level messages disappear.
Figure 18. Disabling
Error-level messages in the Console.
Click the Log Levels dropdown again and re-enable Errors. The
Error-level messages reappear.
Filter by text #
When you want to only view messages that include an exact string, type that string into the Filter text box.
Daveinto the Filter text box. All messages that do not include the string
Daveare hidden. You might also see the
Adolescent Irradiated Espionage Tortoiseslabel. That's a bug.
Figure 19. Filtering out any message that does not include
Davefrom the Filter text box. All the messages reappear.
Filter by regular expression #
When you want to show all messages that include a pattern of text, rather than a specific string, use a regular expression.
/^[AH]/into the Filter text box. Type this pattern into RegExr for an explanation of what it's doing.
Figure 20. Filtering out any message that does not match the pattern
/^[AH]/from the Filter text box. All messages are visible again.
Filter by message source #
When you want to only view the messages that came from a certain URL, use the Sidebar.
Click Show Console Sidebar .
Figure 21. The Sidebar.
Click the Expand icon next to 12 Messages. The Sidebar shows a list of URLs that caused messages to be logged. For example,
log.jscaused 11 messages.
Figure 22. Viewing the source of messages in the Sidebar.
Filter by user messages #
Earlier, when you clicked Log Info, a script called
Error-level message stating that the requested resource could not be found. Messages like that are considered browser messages. You can use the Sidebar to filter out browser messages and only show user messages.
Click 9 User Messages. The browser messages are hidden.
Figure 23. Filtering out browser messages.
Click 12 Messages to show all messages again.
Use the Console alongside any other panel #
What if you're editing styles, but you need to quickly check the Console log for something? Use the Drawer.
Click the Elements tab.
Press Escape. The Console tab of the Drawer opens. It has all of the features of the Console panel that you've been using throughout this tutorial.
Figure 24. The Console tab in the Drawer.
Next steps #
Congratulations, you have completed the tutorial. Click Dispense Trophy to receive your trophy.
- See Console Reference to explore more features and workflows related to the Console UI.
- See Console API Reference to learn more about all of the
consolemethods that weren't covered in this tutorial.
- See Get Started to explore what else you can do with DevTools.