Develop Reference

How do I change the position of a drop down menu in Bootstrap? I tried using data-offset or data-reference but they didn't work

My dropdown menu starts from the left of the page and its position is not relative to the list items.
<div>
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<div class="container justify-content-between">
<a class="navbar-brand" href="#">ARARAT</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse"
data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent"
aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav dropdown-menu-end mx-auto">
<li class="nav-item active">
<a class="nav-link py-3 px-3" href="#" data-bs-toggle="collapse"
data-bs-target=".navbar-collapse.show">Home</a>
</li>
<li class="nav-item">
<a class="nav-link py-3 px-3" href="#" data-bs-toggle="collapse"
data-bs-target=".navbar-collapse.show">About</a>
</li>
<li class="nav-item">
<a class="nav-link py-3 px-3" href="#" data-bs-toggle="collapse"
data-bs-target=".navbar-collapse.show">Products</a>
</li>
<li class="nav-item">
<a class="nav-link py-3 px-3" href="#" data-bs-toggle="collapse"
data-bs-target=".navbar-collapse.show">Services</a>
</li>
<li class="nav-item">
<a class="nav-link dropdown-toggle py-3 px-3" href="#" id="navbarDropdownMenuLink"
role="button" data-bs-toggle="dropdown" aria-expanded="true">Blog</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<li><a class="dropdown-item" href="#">d1</a></li>
<li><a class="dropdown-item" href="#">d2</a></li>
<li><a class="dropdown-item" href="#">d3</a></li>
<li><a class="dropdown-item" href="#">d4</a></li>
</ul>
</li>
<li class="nav-item">
<a class="nav-link dropdown-toggle py-3 px-3" href="#" id="navbarDropdownMenuLink"
role="button" data-bs-toggle="dropdown" aria-expanded="true">Pages</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<li><a class="dropdown-item" href="#">P1</a></li>
<li><a class="dropdown-item" href="#">P2</a></li>
<li><a class="dropdown-item" href="#">P3</a></li>
<li><a class="dropdown-item" href="#">P4</a></li>
</ul>
</li>
<li class="nav-item">
<a class="nav-link py-3 px-3" href="#" data-bs-toggle="collapse"
data-bs-target=".navbar-collapse.show">Contact</a>
</li>
</ul>
<button class="btn bg-transparent fs-6 PX-5 PY-5" type="submit">GET IN TOUCH</button>
</div>
</div>
</nav>
</div>
Here I'm attaching a photo for the result I get... I want the list of (P1, P2, ...) be under the "pages" list item. Thank you

I think why your pages dropdown is not working is you gave the same id to your both dropdown menu.
id="navbarDropdownMenuLink"
Try to change one of the dropdown'd id. Remember, If two Bootstrap dropdown menus have the same id and aria-labelledby values, the first dropdown will function correctly but the second dropdown will not work as expected.

bootstrap navbar dropdown list

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNavDropdown">
<ul class="navbar-nav">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Features</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Pricing</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropdown link
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
</ul>
</div>
</nav>
this is the code for navbar with dropdowns in bootstrap. but the problem is here dropdown is not working when is a toggle to the navbar dropdown icon
code Link: https://getbootstrap.com/docs/4.0/components/navbar/
any suggestions why it isn't working for react??

You need to use reactstrap npm package together with bootstrap. have a look here: https://reactstrap.github.io/

You should use react-bootstrap. It works fine with react and is specially made for react.
https://react-bootstrap.github.io/components/navbar/#navbars-overview

Space between menu items in Bootstrap 4

I am beginner web developer. I make project in Bootstrap 4.
I have small problem with to large space between menu items (top menu, nav)
I have this code:
<nav class="navbar navbar-expand-lg text-body px-md-0 pb-md-0 navbar-light w-100">
<a class="navbar-brand" href="/"><img src="http://roelle.test/img/logo.jpg" class="pb-2"></a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarmenu"
aria-controls="navbarmenu" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon "></span>
</button>
<div class="collapse navbar-collapse" id="navbarmenu">
<ul class="navbar-nav">
<form class="mx-lg-5" action="" method="">
<div class="inner-addon rounded-0 navbar-search-form">
<i class="fa fa-search"></i>
<input type="text" class="form-control" placeholder="Szukaj produktu"
aria-label="Szukaj produktu" name="query"/>
</div>
</form>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="dropdown1" data-toggle="dropdown"
aria-haspopup="true"
aria-expanded="false">Kategorie <i class="fas fa-angle-down"></i></a>
<div class="dropdown-menu" aria-labelledby="dropdown01">
<div class="dropdown">
<a class="dropdown-item dropdown-toggle" href="#"
id="navbarDropdown1" role="button"
data-toggle="dropdown" aria-haspopup="true"
aria-expanded="false">Books <i
class="fas fa-angle-down"></i></a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown1">
<div class="dropdown">
<a class="dropdown-item dropdown-toggle" href="#"
id="navbarDropdown2" role="button"
data-toggle="dropdown" aria-haspopup="true"
aria-expanded="false">- Comic Book <i
class="fas fa-angle-down"></i></a>
<div class="dropdown-menu"
aria-labelledby="navbarDropdown2">
<a class="dropdown-item"
href="produkty/marvel-comic-book">- Marvel Comic Book</a>
<div class="dropdown">
<a class="dropdown-item dropdown-toggle"
href="#"
id="navbarDropdown4"
role="button"
data-toggle="dropdown"
aria-haspopup="true"
aria-expanded="false">- DC Comic Book
<i class="fas fa-angle-down"></i></a>
<div class="dropdown-menu"
aria-labelledby="navbarDropdown4">
<a class="dropdown-item"
href="produkty/computer-science">- Computer Science</a>
</div>
</div>
<a class="dropdown-item"
href="produkty/action-comics">- Action comics</a>
</div>
</div>
<div class="dropdown">
<a class="dropdown-item dropdown-toggle" href="#"
id="navbarDropdown6" role="button"
data-toggle="dropdown" aria-haspopup="true"
aria-expanded="false">- Textbooks <i
class="fas fa-angle-down"></i></a>
<div class="dropdown-menu"
aria-labelledby="navbarDropdown6">
<a class="dropdown-item"
href="produkty/business">- Business</a>
<a class="dropdown-item"
href="produkty/finance">- Finance</a>
</div>
</div>
</div>
</div>
<div class="dropdown">
<a class="dropdown-item dropdown-toggle" href="#"
id="navbarDropdown10" role="button"
data-toggle="dropdown" aria-haspopup="true"
aria-expanded="false">Electronics <i
class="fas fa-angle-down"></i></a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown10">
<div class="dropdown">
<a class="dropdown-item dropdown-toggle" href="#"
id="navbarDropdown11" role="button"
data-toggle="dropdown" aria-haspopup="true"
aria-expanded="false">- TV <i
class="fas fa-angle-down"></i></a>
<div class="dropdown-menu"
aria-labelledby="navbarDropdown11">
<a class="dropdown-item"
href="produkty/led">- LED</a>
<a class="dropdown-item"
href="produkty/blu-ray">- Blu-ray</a>
</div>
</div>
<div class="dropdown">
<a class="dropdown-item dropdown-toggle" href="#"
id="navbarDropdown14" role="button"
data-toggle="dropdown" aria-haspopup="true"
aria-expanded="false">- Mobile <i
class="fas fa-angle-down"></i></a>
<div class="dropdown-menu"
aria-labelledby="navbarDropdown14">
<a class="dropdown-item"
href="produkty/samsung">- Samsung</a>
<a class="dropdown-item"
href="produkty/iphone">- iPhone</a>
<a class="dropdown-item"
href="produkty/xiomi">- Xiomi</a>
</div>
</div>
</div>
</div>
<a class="dropdown-item"
href="produkty/no-1">no 1 </a>
<a class="dropdown-item"
href="produkty/no-1-disable">no 1 disable </a>
</div>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="dropdown2" data-toggle="dropdown"
aria-haspopup="true"
aria-expanded="false">Dla klienta <i class="fas fa-angle-down"></i></a>
<div class="dropdown-menu" aria-labelledby="dropdown01">
<a class="dropdown-item" href="/p/kontakt">Kontakt</a>
<a class="dropdown-item" href="/p/koszty-i-warunki-dostawy">Koszty i warunki dostawy</a>
<a class="dropdown-item" href="/p/o-nas">O nas</a>
<a class="dropdown-item" href="/p/polityka-prywatnosci">Polityka prywatności</a>
<a class="dropdown-item" href="/p/pomoc">Pomoc</a>
<a class="dropdown-item" href="/p/poradnik">Poradnik</a>
<a class="dropdown-item" href="/p/raty">Raty</a>
<a class="dropdown-item" href="/p/regulamin">Regulamin</a>
<a class="dropdown-item" href="/p/reklamacje-i-zwroty">Reklamacje i zwroty</a>
</div>
</li>
<li class="nav-item">
<a class="nav-link" href="http://roelle.test/kontakt">Kontakt</a>
</li>
<li class="nav-item">
<li class="nav-item position-relative">
<a class="nav-link" href="http://roelle.test/koszyk"><img
src="http://roelle.test/img/basket.jpg" class="pl-lg-4 pr-2">
<span
class="badge badge-primary count">0</span>
<span class="d-lg-none d-xl-inline">Koszyk</span></a>
</li>
</ul>
</div>
</nav>
$('.dropdown-menu a.dropdown-toggle').on('click', function(e) {
if (!$(this).next().hasClass('show')) {
$(this).parents('.dropdown-menu').first().find('.show').removeClass("show");
}
var $subMenu = $(this).next(".dropdown-menu");
$subMenu.toggleClass('show');
$(this).parents('li.nav-item.dropdown.show').on('hidden.bs.dropdown', function(e) {
$('.dropdown-submenu .show').removeClass("show");
});
return false;
});
I have preview : http://serwer1356363.home.pl/_nauka/
Why after expanding Category => Books is there such a big gap between Books and Comic Books and then Comics and Marvel Comic Book?
How can I repair it?
Please help me

Remove the line of code shown in the image.
And add the following to your css
.dropdown-menu { margin: 0; padding: 0; }
It should be fine now

EJS - Or (||) Operator in If Statement is Not Working

I'm making a navbar, which I want to display "Login" if the currentUser is null OR "1". EJS doesn't seem to like the || operator in if statements. I put the exact if statement in my app.js file, and it gets triggered for either condition.
<%if(currentUser != null || currentUser != "1"){%>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
<%=currentUser%>
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
<%} else if(currentUser==1 || currentUser==null){%>
<li class="nav-item">
<a class="nav-link" href="/">Login</a>
</li>
<%}%>
There's the code from the EJS file. Thank you.

Hover issue in navbar with Bootstrap 4

I have created a navbar with Bootstrap 4. When I click on a drop-down menu link, it opens and remains open — when I hover on another drop-down link, they overlap.
I want it such that a dropdown link will be closed if I hover on another dropdown link.
Here is the code of my navbar drop-down:
.dropdown:hover>.dropdown-menu {
display: block;
}
<!DOCTYPE html>
<html lang="en">
<head>
<title>
Welcome - Maqbool Solutions
</title>
<link rel="shortcut icon" href="../images/favion_Y13_5.ico" type="image/x-icon">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
<script src="../../js/function.js"></script>
<link rel="stylesheet" href="css/main.css">
<link rel="stylesheet" href="css/style.css">
<link rel="stylesheet" href="font/css/font-awesome.css">
</head>
<body>
<div class="container-fluid">
<!--main container-->
<!-- navbar-->
<nav class="navbar navbar-expand-lg navbar-custom fixed-top" id="navbar" style=" height: 80px;">
<div id="logo">
<a href="index.html">
<h3 class="logo_text">Maqbool Solutions</h3>
</a>
</div>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav ml-auto" id="ul">
<li class="nav-item " align="center">
<i class="fa fa-home " aria-hidden="true"></i>
<a class="nav-link" href="index.html">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-cubes" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Products
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="products/ims/ims.html">Institute Managment Systems</a>
<a class="dropdown-item" href="products/pnms/pnms.html">Pension Managment Systems</a>
<a class="dropdown-item" href="products/pms/pms.html">Property Managment Systems</a>
<a class="dropdown-item" href="products/labms/labms.html">Laboratory Managment Systems</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="products/apps/apps.html">Apps</a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-cogs" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Services
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="services/skill_service.html">Training and Skills</a>
<a class="dropdown-item" href="services/indestrial_services.html">Industry Expertise</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="services/web_service.html">Web services</a>
<a class="dropdown-item" href="services/software_service.html">Software services</a>
<a class="dropdown-item" href="services/animation_service.html">Animation services</a>
<a class="dropdown-item" href="services/graphic_service.html">Graphic services</a>
<a class="dropdown-item" href="services/game_service.html">Game services</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="services/apps_service.html">App services</a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-pencil-square-o" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Training
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="training/soft.html">Software Designing & Development</a>
<a class="dropdown-item" href="training/design.html">Designing & Composing</a>
<a class="dropdown-item" href="training/web.html">Web Designing & Development</a>
<a class="dropdown-item" href="training/animation.html">2D&3D Animation & Development </a>
<a class="dropdown-item" href="training/game.html">Game Development </a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="training/app.html">App Development </a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-briefcase" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
About Us
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="aboutus/hwr.html">Who we are</a>
<a class="dropdown-item" href="aboutus/our_vision.html">Our vision</a>
<a class="dropdown-item" href="aboutus/our_team.html">Our Team</a>
<a class="dropdown-item" href="aboutus/policy.html">Privacy & Policy</a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-graduation-cap" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Career
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="career/jobs.html">Jobs</a>
<a class="dropdown-item" href="career/inter.html">Internship</a>
<a class="dropdown-item" href="career/hiring.html">Our Hirring process</a>
</div>
</li>
<li class="nav-item" align="center">
<i class="fa fa-pencil" aria-hidden="true"></i>
<a class="nav-link" href="contect_us.html">Contact Us</a>
</li>
</ul>
</div>
<hr class="col-md-12 nav_hr">
</nav>
<!--end of navbar-->
</div>
</body>
</html>

You have to add below jQuery code in your custom js file
$('.nav-link').hover(function() {
$(this).closest('.nav-item.dropdown').siblings('.nav-item.dropdown').removeClass('show').find('.dropdown-menu').removeClass('show');
})
The issue is when you click on the dropdown link, a class named show is added to .nav-item.dropdown and .dropdown-menu, So you have to remove show class when you hover on others dropdown link
$('.nav-link').hover(function() {
$(this).closest('.nav-item.dropdown').siblings('.nav-item.dropdown').removeClass('show').find('.dropdown-menu').removeClass('show');
})
.dropdown:hover>.dropdown-menu {
display: block;
}
<!DOCTYPE html>
<html lang="en">
<head>
<title>
Welcome - Maqbool Solutions
</title>
<link rel="shortcut icon" href="../images/favion_Y13_5.ico" type="image/x-icon">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
</head>
<body>
<div class="container-fluid">
<!--main container-->
<!-- navbar-->
<nav class="navbar navbar-expand-lg navbar-custom fixed-top" id="navbar" style=" height: 80px;">
<div id="logo">
<a href="index.html">
<h3 class="logo_text">Maqbool Solutions</h3>
</a>
</div>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav ml-auto" id="ul">
<li class="nav-item " align="center">
<i class="fa fa-home " aria-hidden="true"></i>
<a class="nav-link" href="index.html">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-cubes" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Products
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="products/ims/ims.html">Institute Managment Systems</a>
<a class="dropdown-item" href="products/pnms/pnms.html">Pension Managment Systems</a>
<a class="dropdown-item" href="products/pms/pms.html">Property Managment Systems</a>
<a class="dropdown-item" href="products/labms/labms.html">Laboratory Managment Systems</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="products/apps/apps.html">Apps</a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-cogs" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Services
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="services/skill_service.html">Training and Skills</a>
<a class="dropdown-item" href="services/indestrial_services.html">Industry Expertise</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="services/web_service.html">Web services</a>
<a class="dropdown-item" href="services/software_service.html">Software services</a>
<a class="dropdown-item" href="services/animation_service.html">Animation services</a>
<a class="dropdown-item" href="services/graphic_service.html">Graphic services</a>
<a class="dropdown-item" href="services/game_service.html">Game services</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="services/apps_service.html">App services</a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-pencil-square-o" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Training
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="training/soft.html">Software Designing & Development</a>
<a class="dropdown-item" href="training/design.html">Designing & Composing</a>
<a class="dropdown-item" href="training/web.html">Web Designing & Development</a>
<a class="dropdown-item" href="training/animation.html">2D&3D Animation & Development </a>
<a class="dropdown-item" href="training/game.html">Game Development </a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="training/app.html">App Development </a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-briefcase" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
About Us
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="aboutus/hwr.html">Who we are</a>
<a class="dropdown-item" href="aboutus/our_vision.html">Our vision</a>
<a class="dropdown-item" href="aboutus/our_team.html">Our Team</a>
<a class="dropdown-item" href="aboutus/policy.html">Privacy & Policy</a>
</div>
</li>
<li class="nav-item dropdown" align="center">
<i class="fa fa-graduation-cap" aria-hidden="true"></i>
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Career
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="career/jobs.html">Jobs</a>
<a class="dropdown-item" href="career/inter.html">Internship</a>
<a class="dropdown-item" href="career/hiring.html">Our Hirring process</a>
</div>
</li>
<li class="nav-item" align="center">
<i class="fa fa-pencil" aria-hidden="true"></i>
<a class="nav-link" href="contect_us.html">Contact Us</a>
</li>
</ul>
</div>
<hr class="col-md-12 nav_hr">
</nav>
<!--end of navbar-->
</div>
</body>
</html>

In your code, while mouse over or click event is fired , "show" class is applied to child menu (dropdown-menu) element.
So you can override that class like:
.dropdown-menu.show {
display: none;
}
to solve your issue and to display menu items only on hover

Simple add following CSS lines:
.dropdown:hover > .dropdown-menu,
.dropdown:hover > .dropdown-menu.show {
display: block;
}
.dropdown > .dropdown-menu,
.dropdown > .dropdown-menu.show {
display: none;
}