Console API reference

Kayce Basques

Sofia Emelianova

Use the Console API to write messages to the Console from your JavaScript. See Get started with logging messages to the Console for an interactive introduction to the topic.

See Console utilities API reference if you're looking for the convenience methods like debug(function) or monitorEvents(node) which are only available from the Console.

console.assert(expression, object)

Log level : Error

Writes an error to the console when expression evaluates to false .

  const 
  
 x 
  
 = 
  
 5 
 ; 
 const 
  
 y 
  
 = 
  
 3 
 ; 
 const 
  
 reason 
  
 = 
  
 'x is expected to be less than y' 
 ; 
 console 
 . 
 assert 
 ( 
 x 
 < 
 y 
 , 
  
 { 
 x 
 , 
  
 y 
 , 
  
 reason 
 }); 
 

console.clear()

Clears the console.

  console 
 . 
 clear 
 (); 
 

If Preserve Log is enabled, console.clear() is disabled.

Alternatively, you can Clear the Console by clicking theicon.

console.count([label])

Log level : Info

Writes the number of times that count() has been invoked at the same line and with the same label . Call console.countReset([label]) to reset the count.

  console 
 . 
 count 
 (); 
 console 
 . 
 count 
 ( 
 'coffee' 
 ); 
 console 
 . 
 count 
 (); 
 console 
 . 
 count 
 (); 
 

console.countReset([label])

Resets a count.

  console 
 . 
 countReset 
 (); 
 console 
 . 
 countReset 
 ( 
 'coffee' 
 ); 
 

console.createTask(name)

Returns a Task instance that associates the current stack trace with the created task object. You can later use this task object to run a function ( f in the following example). The task.run(f) executes an arbitrary payload and forwards the return value back to the caller.

  // Task creation 
 const 
  
 task 
  
 = 
  
 console 
 . 
 createTask 
 ( 
 name 
 ); 
 // Task execution 
 task 
 . 
 run 
 ( 
 f 
 ); 
  
 // instead of f(); 
 

The task forms a link between the creation context and the context of the async function. This link lets DevTools show better stack traces for async operations. For more information, see Linked Stack Traces .

console.debug(object [, object, ...])

Log level : Verbose

Identical to console.log(object [, object, ...]) except different log level.

  console 
 . 
 debug 
 ( 
 'debug' 
 ); 
 

console.dir(object)

Log level : Info

Prints a JSON representation of the specified object.

  console 
 . 
 dir 
 ( 
 document 
 . 
 head 
 ); 
 

console.dirxml(node)

Log level : Info

Prints an XML representation of the descendants of node .

  console 
 . 
 dirxml 
 ( 
 document 
 ); 
 

console.error(object [, object, ...])

Log level : Error

Prints object to the Console, formats it as an error, and includes a stack trace.

  console 
 . 
 error 
 ( 
 "I'm sorry, Dave. I'm afraid I can't do that." 
 ); 
 

console.group(label)

Visually groups messages together until console.groupEnd(label) is called. Use console.groupCollapsed(label) to collapse the group when it's initially logged to the Console.

  const 
  
 label 
  
 = 
  
 'Adolescent Irradiated Espionage Tortoises' 
 ; 
 console 
 . 
 group 
 ( 
 label 
 ); 
 console 
 . 
 info 
 ( 
 'Leo' 
 ); 
 console 
 . 
 info 
 ( 
 'Mike' 
 ); 
 console 
 . 
 info 
 ( 
 'Don' 
 ); 
 console 
 . 
 info 
 ( 
 'Raph' 
 ); 
 console 
 . 
 groupEnd 
 ( 
 label 
 ); 
 

Additionally, you can nest groups.

  const 
  
 timeline1 
  
 = 
  
 'New York 2012' 
 ; 
 const 
  
 timeline2 
  
 = 
  
 'Camp Lehigh 1970' 
 ; 
 console 
 . 
 group 
 ( 
 timeline1 
 ); 
 console 
 . 
 info 
 ( 
 'Mind' 
 ); 
 console 
 . 
 info 
 ( 
 'Time' 
 ); 
 console 
 . 
 group 
 ( 
 timeline2 
 ); 
 console 
 . 
 info 
 ( 
 'Space' 
 ); 
 console 
 . 
 info 
 ( 
 'Extra Pym Particles' 
 ); 
 console 
 . 
 groupEnd 
 ( 
 timeline2 
 ); 
 console 
 . 
 groupEnd 
 ( 
 timeline1 
 ); 
 

console.groupCollapsed(label)

Same as console.group(label) , except the group is initially collapsed when it's logged to the Console.

console.groupEnd(label)

Stops visually grouping messages. See console.group .

console.info(object [, object, ...])

Log level : Info

Identical to console.log(object [, object, ...]) .

  console 
 . 
 info 
 ( 
 'info' 
 ); 
 

console.log(object [, object, ...])

Log level : Info

Prints a message to the Console.

  console 
 . 
 log 
 ( 
 'log' 
 ); 
 

console.table(array [, columns])

Log level : Info

Logs an array of objects as a table.

  var 
  
 people 
  
 = 
  
 [ 
 { 
     
 first 
 : 
  
 'René' 
 , 
     
 last 
 : 
  
 'Magritte' 
 , 
 }, 
 { 
     
 first 
 : 
  
 'Chaim' 
 , 
     
 last 
 : 
  
 'Soutine' 
 , 
     
 birthday 
 : 
  
 '18930113' 
 , 
 }, 
 { 
     
 first 
 : 
  
 'Henri' 
 , 
     
 last 
 : 
  
 'Matisse' 
 , 
 } 
 ]; 
 console 
 . 
 table 
 ( 
 people 
 ); 
 

By default, console.table() logs all table data. To display a single column or a subset of columns, you can use the second optional parameter and specify column name or names as a string or an array of strings. For example:

  console 
 . 
 table 
 ( 
 people 
 , 
  
 [ 
 'last' 
 , 
  
 'birthday' 
 ]); 
 

console.time([label])

Starts a new timer. Call console.timeEnd([label]) to stop the timer and print the elapsed time to the Console.

  console 
 . 
 time 
 (); 
 for 
  
 ( 
 var 
  
 i 
  
 = 
  
 0 
 ; 
  
 i 
 < 
 100000 
 ; 
  
 i 
 ++ 
 ) 
  
 { 
 let 
  
 square 
  
 = 
  
 i 
  
 ** 
  
 2 
 ; 
 } 
 console 
 . 
 timeEnd 
 (); 
 

console.timeEnd([label])

Log level : Info

Stops a timer. See console.time() .

console.trace()

Log level : Info

Prints a stack trace to the Console.

  const 
  
 first 
  
 = 
  
 () 
  
 = 
>  
 { 
  
 second 
 (); 
  
 }; 
 const 
  
 second 
  
 = 
  
 () 
  
 = 
>  
 { 
  
 third 
 (); 
  
 }; 
 const 
  
 third 
  
 = 
  
 () 
  
 = 
>  
 { 
  
 fourth 
 (); 
  
 }; 
 const 
  
 fourth 
  
 = 
  
 () 
  
 = 
>  
 { 
  
 console 
 . 
 trace 
 (); 
  
 }; 
 first 
 (); 
 

console.warn(object [, object, ...])

Log level : Warning

Prints a warning to the Console.

  console 
 . 
 warn 
 ( 
 'warn' 
 );