JS Misc

jss.js

const oldPackage = JSON.parse(JSON.stringify(this.package)); // copy object

setTimeout(() => {}, 1000);

// Arrays
array.splice(pos, 1);        // Removes the first element of the array

// clone array
let arr2 = [...arr];

// reverse array
fruits.reverse();

import debounce from 'lodash/debounce';

loadStock: debounce(function (name) {
    console.log('loadstock', name);
    this.loadStockFetch(name)
}, 1000),

//promises
async getTeams(match) {
  return new Promise(async (resolve, reject) => {
    resolve(data);
  });
}
async function isEmailExist(email) {
    let count = await new Promise((resolve, reject) => {
        db.count({email: email}, (err, count) => {
            if (err) reject(err);
            resolve(count);
        });
    });
    return count > 0;
}

var start = new Date();
start.setHours(0,0,0,0);

var end = new Date();
end.setHours(23,59,59,999);

alert( start.toUTCString() + ':' + end.toUTCString() );

new Date().getTime();
if (!Date.now) {
    Date.now = function() { return new Date().getTime(); }
}
To get the timestamp in seconds, you can use:

Math.floor(Date.now() / 1000)

var days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
var d = new Date(dateString);
var dayName = days[d.getDay()];

// get Mon, Tue
var d = new Date(dateString);
var dayName = d.toString().split(' ')[0];

if (a === null)

Check for undefined

if (typeof a === "undefined")
// or
if (a === undefined)

Short cut

if (!a) {
    // `a` is falsey, which includes `undefined` and `null`
    // (and `""`, and `0`, and `NaN`, and [of course] `false`)
}