Difference between "process.stdout.write" and "console.log" in node.js?

Solution 1:

console.log() calls process.stdout.write with formatted output. See format() in console.js for the implementation.

Currently (v0.10.ish):

Console.prototype.log = function() {
  this._stdout.write(util.format.apply(this, arguments) + '\n');
};

Solution 2:

Looking at the Node docs apparently console.log is just process.stdout.write with a line-break at the end:

console.log = function (d) {
  process.stdout.write(d + '\n');
};

Source: http://nodejs.org/docs/v0.3.1/api/process.html#process.stdout

Solution 3:

I know this is a very old question but I didn't see anybody talking about the main difference between process.stdout.write and console.log and I just want to mention it.

As Mauvis Leford and TK-421 pointed out, the console.log adds a line-break character at the end of the line (\n) but that's not all what it does.

The code has not changed since at least 0.10.X version and now we have a a 5.X version.

Here is the code:

Console.prototype.log = function() {
  this._stdout.write(util.format.apply(this, arguments) + '\n');
};

As you can see, there is a part that says .apply(this, arguments) and that makes a big difference on functionality. It is easier to explain that with examples:

process.stdout.write has a very basic functionality, you can just write something in there, like this:

process.stdout.write("Hello World\n"); 

If you don't put the break line at the end you will get a weird character after your string, something like this:

process.stdout.write("Hello World"); //Hello World% 

(I think that means something like "the end of the program", so you will see it only if you process.stdout.write was used at the end of your file and you didn't add the break line)

On the other hand, console.log can do more.

1. You can use it in the same way

   console.log("Hello World"); //You don't need the break line here because it was already formated and also that weird character did disappear

2. You can write more than one string

   console.log("Hello", "World");

3. You can make associations

   console.log("Hello %s", "World") //Useful when "World" is inside a variable

An that's it, that added functionality is given thanks to the util.format.apply part (I could talk a lot about what exactly this does but you get my point, you can read more here).

I hope somebody find this information useful.

Solution 4:

One big difference that hasn't been mentioned is that process.stdout only takes strings as arguments (can also be piped streams), while console.log takes any Javascript data type.

e.g:

// ok
console.log(null)
console.log(undefined)
console.log('hi')
console.log(1)
console.log([1])
console.log({one:1})
console.log(true)
console.log(Symbol('mysymbol'))

// any other data type passed as param will throw a TypeError
process.stdout.write('1')

// can also pipe a readable stream (assuming `file.txt` exists)
const fs = require('fs')
fs.createReadStream('file.txt').pipe(process.stdout)