xexi

var test = 'myfile.txt';

console.log(test.match(/\.[0-9a-z]+$/i)[0]);

xexi

//var date1 = '20170602110357';
//var date2 = '2016-05-13 04:06:10'
//var date3 = '2014-02-27T22:00:00.000Z'
//var date4 = '2016/03/22 23:11:06'

function escapeRegExp(s) {
    return s.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
}

function replaceAll(s, find, replace) {

xexi

function checkNested(obj /*, level1, level2, ... levelN*/) {
  var args = Array.prototype.slice.call(arguments, 1);

  for (var i = 0; i < args.length; i++) {
    if (!obj || !obj.hasOwnProperty(args[i])) {
      return false;
    }
    obj = obj[args[i]];
  }
  return true;

xexi

db.collection.aggregate( [
	{ $match: { 'dept': "service", 'condition': '0' } },
	{ $group: { _id: { first: "$distinct_col1", second: "$distinct_col1" },  // distinct option
		id_tag : { $min: "$tag" }, // projection
		count: { $sum:1 } // group count
	  }
	},
	{ $sort: { '_.id.regdate': 1 }}, // make sure sort by group id // 1 asc
	{ $skip: 0 },
	{ $limit: 5 },

xexi

db.collection('my_collection').find( { 'findData': 'MorefindOption', 
                              $or : [ 
                                  { 'name' : { $regex: 'searchWord' , $options: 'ix' } }, 
                                  { 'adress' : { $regex: 'searchWord' , $options: 'ix' } } 
                              ] })
                              
                              
// more option available at google search -> mongodb regex option
// -> in mongo cli { name : /.*searchWord.*/i }

xexi

var n = 5;
var nn = [n];
            for (var i = 1; i < 5; i++) {
                nn.push(nn[0] - i);
            }
console.log(JSON.stringify(nn));

xexi

db.collection.find({ "findData": "blabla" }).sort({"orderData": -1}).limit(1)

xexi

db.collection('myCollection').find( { 'findData': { $exists: true } }).toArray( (err, results) => {});

xexi

var arr = [];

// for any falsy value (0, "", NaN, null, undefined, or of course, false):

if (!myarray[0]){
  // isEmpty
} else {
  // notEmpty
}

xexi

let bulk = db.collection('myCollection').initializeOrderedBulkOp();

  for(let i=0; i < arr.length; i++){
      bulk.find( {findData: arr[i]} ).upsert().updateOne(
          {
              $set: { modData: 'yolo' }
          }
      );
  }