..:: Source code - 01callback.js ::..

/**
 * basic usage of callbacks
 */

/* MAIN FUNCTION */
function addnum(x, cb) {
  console.log('x=' + x);
  cb(x);
}


/* CALLBACKS */

//callback which adds 5
function cb5(a) {
  var rez = a + 5;
  console.log('a+5=' + rez);
}

//callback which adds 100
function cb100(a) {
  var rez = a + 100;
  console.log('a+100=' + rez);
}

//execute main function with callback cb5
addnum(2, cb5);

console.log();

//execute main function with callback cb100
addnum(2, cb100);


/* $node 01callback
x=2
a+5=7

x=2
a+100=102
 */

..:: NodeJS Console - 01callback.js ::..

x=2
a+5=7

x=2
a+100=102

$ps -aux | grep node (list all node processes)
sasa         849  0.5  0.5 1319168 87880 ?       Ssl  Oct08 283:26 node /home/sasa/regoch/regoch-www/server
sasa         880  0.4  0.5 1319240 87772 ?       Ssl  Oct08 235:55 node /home/sasa/dex8/dex8-www/server/index.js
sasa         890  0.5  0.5 11797800 85608 ?      Ssl  Oct08 334:44 node /home/sasa/mikosoft_hr/www-mikosoft-hr/server/index.js
sasa         903  0.7  0.4 1329652 81708 ?       Ssl  Oct08 431:22 node /home/sasa/mikosoft-info/api-mikosoft-info/starter.js
sasa         929  0.4  0.4 1300184 68808 ?       Ssl  Oct08 226:27 node /home/sasa/mikosoft-info/www-mikosoft-info/server/index.js
sasa         943  0.4  0.4 1300808 67028 ?       Ssl  Oct08 233:34 node /home/sasa/dex8/dex8-kiosk/server/index.js
sasa         980  0.6  0.5 11798124 83860 ?      Ssl  Oct08 364:58 node /home/sasa/mikosoft-info/dodo-mikosoft-info/server/index.js
sasa         981  0.7  0.6 1148036 104984 ?      Ssl  Oct08 395:22 node /home/sasa/voovuu/voovuu-api/starter.js
sasa        1039  0.9  1.4 11945524 245884 ?     Ssl  Oct08 555:27 node /home/sasa/voovuu/voovuu-pub/server/index.js
sasa     2044488  0.3  0.4 1298112 66784 ?       Ssl  Nov01  77:33 node /home/sasa/dex8/dex8-panel/server/index.js
sasa     2574087  0.3  0.4 11792920 77200 ?      Ssl  Nov08  42:10 node /home/sasa/@mikosoft/dodo-examples/server/index.js
sasa     2702010  0.4  0.6 22296696 100076 ?     Ssl  Nov10  35:20 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702011  0.3  0.4 1100276 66352 ?       Ssl  Nov10  31:27 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702018  0.3  0.3 1099884 65276 ?       Ssl  Nov10  31:30 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702019  0.3  0.4 1100516 66636 ?       Ssl  Nov10  31:29 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702046  0.9  0.7 22311780 124020 ?     Ssl  Nov10  84:35 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702047  0.3  0.4 1100260 65816 ?       Ssl  Nov10  31:46 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702088  0.3  0.4 1100264 66208 ?       Ssl  Nov10  31:30 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702089  0.3  0.4 1100264 66328 ?       Ssl  Nov10  31:27 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702137  0.3  0.4 1099864 66320 ?       Ssl  Nov10  31:17 node /home/sasa/dex8/dex8-worker/starter.js
sasa     2702139  0.4  0.6 22297196 101324 ?     Ssl  Nov10  35:51 node /home/sasa/dex8/dex8-worker/starter.js
sasa     3097623  1.1  0.8 11716736 131820 ?     Ssl  Nov13  44:28 node /home/sasa/dex8/dex8-api/starter.js
www-data 3369112  0.0  0.0   2608   604 ?        S    09:28   0:00 sh -c ps -aux | grep node
www-data 3369114  0.0  0.0   3304   732 ?        S    09:28   0:00 grep node