Node.js - Console
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.
| Sr.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 −
Live Demo
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
