Node Console Module

console

The console module is straightforward. As with anything, there’s bound to be something of interest if we look closely.

stdout

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

Print to stdout. You can use printf formatting.

console.dir(obj)

Logs result of util.inspect.

Time

console.time(label)
console.timeEnd(label)

These are cool methods for timing how long something takes.

console.time('foo');

setTimeout(function () {
  console.timeEnd('foo');
}, 300);

// prints "foo: 303ms"

stderr

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

Print messages, like log and info, but to stderr.

console.trace(label)

Prints a stack trace.

var f1 = function (fn) {
  // step 4
  // step 6
  fn();
};

var f2 = function iHaveAName () {
  // step 3
  f1(function soDoI () {
    // step 5
    f1(function () {
      // step 7
      console.trace('a label');
    });
  });
};

var f3 = function () {
  // step 2
  f2();
};

var f4 = function () {
  // step 1
  f3();
};

f4();

console output

Trace: a label
    at /home/grizzle/code/node-study/modules/console.js:15:15
    at f1 (/home/grizzle/code/node-study/modules/console.js:6:3)
    at soDoI (/home/grizzle/code/node-study/modules/console.js:13:5)
    at f1 (/home/grizzle/code/node-study/modules/console.js:6:3)
    at iHaveAName (/home/grizzle/code/node-study/modules/console.js:11:3)
    at f3 (/home/grizzle/code/node-study/modules/console.js:22:3)
    at f4 (/home/grizzle/code/node-study/modules/console.js:27:3)
    at Object.<anonymous> (/home/grizzle/code/node-study/modules/console.js:30:1)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)

Notice that it’s pretty good at figuring out which method the stack is in, but if it’s an anonymous function, there’s not name to print.

console.assert(expression, [message])

Throws an error if expression is falsy.

Summary

That’s it. There’s not much to it, so get on to the next module. If you’re interested, here’s the source.