Bootstrap 4 not rendering completely reactjs - reactjs

Question

I have searched for Bootstrap 4 templates of a navbar with login and I came across this. So, I have converted it and this is the code:
import React, {Component} from 'react';
class HeaderComponent extends Component {
render() {
return (
<nav className="navbar navbar-expand-lg navbar-dark bg-dark fixed-top">
<div className="container">
<a className="navbar-brand" href="/">Reddit</a>
<button className="navbar-toggler border-0" type="button" data-toggle="collapse" data-target="#exCollapsingNavbar">
☰
</button>
<div className="collapse navbar-collapse" id="exCollapsingNavbar">
<ul className="nav navbar-nav">
<li className="nav-item">Home</li>
<li className="nav-item">Popular</li>
<li className="nav-item">All</li>
</ul>
<ul className="nav navbar-nav flex-row justify-content-between ml-auto">
<li className="nav-item order-2 order-md-1"><i className="fa fa-cog fa-fw fa-lg"></i></li>
<li className="dropdown order-1">
<button type="button" id="dropdownMenu1" data-toggle="dropdown" className="btn btn-outline-secondary dropdown-toggle">Login <span className="caret"></span></button>
<ul className="dropdown-menu dropdown-menu-right mt-2">
<li className="px-3 py-2">
<form className="form">
<div className="form-group">
<input id="emailInput" placeholder="Email" className="form-control form-control-sm" type="text" required="" />
</div>
<div className="form-group">
<input id="passwordInput" placeholder="Password" className="form-control form-control-sm" type="text" required="" />
</div>
<div className="form-group">
<button type="submit" className="btn btn-primary btn-block">Login</button>
</div>
<div className="form-group text-center">
<small>Forgot password?</small>
</div>
</form>
</li>
</ul>
</li>
</ul>
</div>
</div>
</nav>
)
}
}
export default HeaderComponent;
The problem here is the dropdown of the login option is not getting rendered. And when I minimize the window, all the options are hidden but pressing the button doesnt uncollapse the menu.

Answer 1

I think that probably you have something with an higher z-index because your code currently works in the React JSFiddle: https://jsfiddle.net/x9g7683t/
HTML:
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" integrity="sha384-WskhaSGFgHYWDcbwN70/dfYBj47jz9qbsMId/iRN3ewGhXQFZCSftd1LZCfmhktB" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js" integrity="sha384-smHYKdLADwkXOn1EmN1qk/HfnUcbVRZyYmZ4qpPea6sjB/pTJ0euyQp0Mk8ck+5T" crossorigin="anonymous"></script>
<div id="container">
<!-- This element's contents will be replaced with your component. -->
</div>
I've imported all Bootstrap scripts (maybe can help).
The code is a copy and paste of your component render.