comparing callback binding, calling, closures

gistfile1.txt

function nop() { }

// static functions, .bind them
function doop1(a, cb) { cb(); }
function doop2(a, b, cb) { cb(); }
function backupFile1(filename, cb) {
  doop1(filename + '.bak', step2.bind(undefined, filename, cb));
}
function step2(filename, cb, err) {
  doop2(filename, filename + '.bak', cb);
}

// closures
function backupFile2(filename, cb) {
  doop1(filename + '.bak', function(err) {
    doop2(filename, filename + '.bak', cb);
  });
}

// functions take a this-pointer
function doop1a(a, cb, thisp) { cb.call(thisp); }
function doop2a(a, b, cb, thisp) { cb.call(thisp); }
function backupFile3(filename, cb) {
  doop1a(filename + '.bak', step2a, { fn: filename, cb: cb });
}
function step2a(err) {
  doop2a(this.fn, this.fn + '.bak', this.cb);
}


var ii, mem, endmem;
while (true) {
  mem = process.memoryUsage().heapUsed;
  for (ii = 0; ii < 1000; ++ii) {
    backupFile1('a', nop);
  }
  endmem = process.memoryUsage().heapUsed;
  console.log('bind:    ' + ((endmem - mem) / 1000));
  mem = process.memoryUsage().heapUsed;
  for (ii = 0; ii < 1000; ++ii) {
    backupFile2('a', nop);
  }
  endmem = process.memoryUsage().heapUsed;
  console.log('closure: ' + ((endmem - mem) / 1000));
  mem = process.memoryUsage().heapUsed;
  for (ii = 0; ii < 1000; ++ii) {
    backupFile3('a', nop);
  }
  endmem = process.memoryUsage().heapUsed;
  console.log('thisp:   ' + ((endmem - mem) / 1000));
}