..:: 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         831  0.4  0.4 1301596 72524 ?       Ssl  Jun15   8:14 node /home/sasa/.pm2/modules/pm2-logrotate/node_modules/pm2-logr
sasa         843  0.4  0.6 11696520 100944 ?     Ssl  Jun15   7:33 node /home/sasa/dex8/dex8-api/starter.js
sasa         858  0.3  0.3 1034000 61932 ?       Ssl  Jun15   6:00 node /home/sasa/regoch/regoch-www/server
sasa         867  0.3  0.3 1292980 59616 ?       Ssl  Jun15   5:52 node /home/sasa/dex8/dex8-panel/server/index.js
sasa         886  0.8  0.5 11807896 89300 ?      Ssl  Jun15  13:46 node /home/sasa/dex8/dex8-www/server/index.js
sasa         888  0.3  0.4 11790616 74972 ?      Ssl  Jun15   6:19 node /home/sasa/mikosoft_hr/www-mikosoft-hr/server/index.js
sasa         904  0.6  0.4 1329612 81980 ?       Ssl  Jun15  10:43 node /home/sasa/mikosoft-info/api-mikosoft-info/starter.js
sasa         910  0.3  0.3 1295860 63532 ?       Ssl  Jun15   5:53 node /home/sasa/mikosoft-info/www-mikosoft-info/server/index.js
sasa         969  0.3  0.3 1226436 56980 ?       Ssl  Jun15   5:48 node /home/sasa/dex8/dex8-kiosk/server/index.js
sasa         970  0.4  0.5 11809840 91176 ?      Ssl  Jun15   8:16 node /home/sasa/mikosoft-info/dodo-mikosoft-info/server/index.js
sasa        1010  0.4  0.5 1138968 92340 ?       Ssl  Jun15   7:34 node /home/sasa/voovuu/voovuu-api/starter.js
sasa        1016  0.6  0.6 11805592 103176 ?     Ssl  Jun15  10:49 node /home/sasa/voovuu/voovuu-pub/server/index.js
sasa        1086  0.3  0.4 11662816 76748 ?      Ssl  Jun15   6:13 node /home/sasa/@mikosoft/dodo-examples/server/index.js
sasa        1089  0.3  0.4 1101148 66216 ?       Ssl  Jun15   6:04 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1159  0.3  0.4 1101152 66580 ?       Ssl  Jun15   6:02 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1160  0.3  0.4 1101148 65732 ?       Ssl  Jun15   6:02 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1241  0.3  0.3 1102488 64340 ?       Ssl  Jun15   6:00 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1242  0.3  0.4 22279612 79048 ?      Ssl  Jun15   6:17 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1323  0.3  0.4 1101148 65940 ?       Ssl  Jun15   6:02 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1324  0.3  0.3 1101152 65280 ?       Ssl  Jun15   6:01 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1398  0.3  0.4 1101152 66080 ?       Ssl  Jun15   6:00 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1400  0.3  0.4 1101148 65936 ?       Ssl  Jun15   6:03 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1465  0.3  0.3 1101152 65340 ?       Ssl  Jun15   6:00 node /home/sasa/dex8/dex8-worker/starter.js
sasa        1475  0.3  0.6 11811364 106668 ?     Ssl  Jun15   6:39 node /home/sasa/mikosoft-info/crypto-mikosoft-info/server/index.
www-data   85277  0.0  0.0   2608   532 ?        S    07:17   0:00 sh -c ps -aux | grep node
www-data   85279  0.0  0.0   3304   656 ?        S    07:17   0:00 grep node