JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" name="s" id="search" value="Search for post">

JavaScript

$('#search').focus(function() {           
    if($(this).val() == 'Search for post'){ 
         $(this).val('');
    }else
    {
        $(this).val('dsfsdf');
    }
});