Check out example codes for "how to apply hover through inline css". It will help you in understanding the concepts better.

Code Example 1

document.head.insertAdjacentHTML('beforeend', '<style>#mydiv:hover{color:red;}</style>');

Code Example 2

document.getElementById("mydiv").onmouseover= function(e){this.className += ' my-special-class'; };
document.getElementById("mydiv").onmouseleave= function(e){this.className = this.className.replace('my-special-class',''); };

Code Example 3

<a href="abc.html"
   onMouseOver="this.style.color='#0F0'"
   onMouseOut="this.style.color='#00F'" >Text</a>

Learn ReactJs, React Native from akashmittal.com