Node.js - Console


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Node.js console is a global object and is used to print different levels of messages to stdout and stderr. There are built-in methods to be used for printing informational, warning, and error messages.

It is used in synchronous way when the destination is a file or a terminal and in asynchronous way when the destination is a pipe.

Console Methods

Following is a list of methods available with the console global object.

S.No. Method & Description
1

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

Prints to stdout with newline. This function can take multiple arguments in a printf()-like way.

2

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

Prints to stdout with newline. This function can take multiple arguments in a printf()-like way.

3

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

Prints to stderr with newline. This function can take multiple arguments in a printf()-like way.

4

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

Prints to stderr with newline. This function can take multiple arguments in a printf()-like way

5

console.dir(obj[, options])

Uses util.inspect on obj and prints resulting string to stdout.

6

console.time(label)

Mark a time.

7

console.timeEnd(label)

Finish timer, record output.

8

console.trace(message[, ...])

Print to stderr 'Trace :', followed by the formatted message and stack trace to the current position.

9

console.assert(value[, message][, ...])

Similar to assert.ok(), but the error message is formatted as util.format(message...).

Example

Let us create a js file named main.js with the following code −

console.info("Program Started");

var counter = 10;
console.log("Counter: %d", counter);

console.time("Getting data");
//
// Do some processing here...
// 
console.timeEnd('Getting data');

console.info("Program Ended")

Now run the main.js to see the result −

node main.js

Verify the Output.

Program Started
Counter: 10
Getting data: 0ms
Program Ended

nodejs_global_objects.htm

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