Convert NaN to 0 in JavaScript

n = n || 0;
n = n ? n : 0;
n = +n || 0;
function getNumVal(val) {
    if (isNaN(val)) {
      return 0;
    }
    return val;
 }

Handling TypeError: Cannot read properties of undefined (reading x)

function myFunc(a) {
    if (a !== undefined) {
        console.log(a.b);
    }
}

var myVar;
myFunc(myVar);

To extract the string containing in the path of the URL for the location

var path = window.location.pathname; // https://vj2tech.hashnode.dev/javascript-utility-for-daily-work
path = path.split('/');
var nameplate = path[1];  
console.log(nameplate);  // javascript-utility-for-daily-work

Find the number of days between two dates

const dateDiff = (date1, date2) => Math.ceil(Math.abs(date1.getTime() - date2.getTime()) / 86400000);

console.log(dateDiff)

Generate a Random Integer within the given range with Math.random function

const randomNumber = (min, max) => Math.floor(Math.random() * (max - min)) + min;

randomNumber(1, 5);    // 4

Wait for an element (class or Id) to load in Dom and then trigger the function

@{String} querySelector - Selector of element to wait for loading

@{Integer} timeout - Milliseconds to wait before timing out, or 0 for no timeout

function waitForElementtoLoad(querySelector, timeout){
    return new Promise((resolve, reject)=>{
      var timer = false;
      if(document.querySelectorAll(querySelector).length) return resolve();
      const observer = new MutationObserver(()=>{
        if(document.querySelectorAll(querySelector).length){
          observer.disconnect();
          if(timer !== false) clearTimeout(timer);
          return resolve();
        }
      });
      observer.observe(document.body, {
        childList: true, 
        subtree: true
      });
      if(timeout) timer = setTimeout(()=>{
        observer.disconnect();
        reject();
      }, timeout);
    });
  }

  waitForElementtoLoad("#dropdown-label-1", 4000).then(function(){
      alert("element is loaded.. do stuff");
  }).catch(()=>{
      alert("element did not load in 4 seconds");
  });