nodejs tips

const _ = require('lodash');

// sum of array's elements (lodash)
_.sum([4, 2, 8, 6]);
//or
[1, 2, 3, 4].reduce((a, b) => a + b, 0)

// max-min element of array
Math.max( ...arr );

// extract arrays
var seasons = ['winter', 'spring', 'summer', 'autumn'];  
var head, restArray;  
[head, ...restArray] = seasons;

// array contstruction with ...
var numbers1 = [...initial, 5, 7];

// native operations with array
var myData = [];
myData.push(1); // add at the end 
myData.unshift(2); // add to the top 

// variable interpolation
var s = `hello ${my_name}`

// iterate characters (from string)
[...text].forEach(c => console.log(c))
for (var x = 0, c=''; c = text.charAt(x); x++) {     console.log(c);  }
// ES5 without the for loop:
text.split('').forEach(function(c) {    console.log(c);  });
// With the `of` operator
for (const c of text) {    console.log(c) }

// string functions: (see also https://www.w3schools.com/jsref/jsref_obj_string.asp )
word.charCodeAt(x)

// References:
// 1. https://dmitripavlutin.com/how-three-dots-changed-javascript/
// 2. JavaScript compatibility list http://kangax.github.io/compat-table/es2016plus/