How to show hide option list items using jQuery?

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
	<style>	
	a{
    color:#02D;
    text-decoration: none;
	}
	a:hover{
		color:#F50;
		text-decoration: underline;
	}
	.SubCategoryBox{
		width: 600px;
		margin: 0 auto;
		text-align: center;
		margin-top: 40px;
		border: 1px solid #000;
	}
	.SubCategoryBox ul{
		list-style: none;
	}
	.SubCategoryBox ul li{
		display: block;
		float: left;
		width: 200px;
		line-height: 20px;
	}
	.showmore{
		clear:both;
		text-align: center;
		padding-top: 10px;
	}
	.showmore a{
		display: block;
		width: 120px;
		margin: 0 auto;
		line-height: 24px;
		border: 1px solid #AAA;
	}
	.showmore a span{
		padding-left: 15px;
	}
	.promoted a{
		color:#F50;
	}       
	</style>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js"></script>
    <script>
	$(function(){
    let $category = $("ul li:gt(5):not(:last)");
    $category.hide();

    let $toggleBtn = $("div.showmore>a");

    $toggleBtn.click(function(){
        if($category.is(":visible")){
            $category.hide();
            $(this).find("span").text("Show all brands")
            $("ul li").removeClass("promoted");
        }else{
            $category.show();
            $(this).find("span").text("Streamline display brand");
            $("ul li").filter(":contains('Canon'),:contains('Nikon'),:contains('Olympus')").addClass("promoted");
        }
        return false;
    })


});
	</script>
</head>
<body>
<div class="SubCategoryBox">
    <ul>
        <li><a href="#">Canon</a></li>
        <li><a href="#">Sony</a></li>
        <li><a href="#">Samsung </a></li>
        <li><a href="#">Nikon</a></li>
        <li><a href="#">Olympus</a></li>
        <li><a href="#">Panasonic</a></li>
        <li><a href="#">Canon</a></li>
        <li><a href="#">Sony</a></li>
        <li><a href="#">Samsung </a></li>
        <li><a href="#">Nikon</a></li>
        <li><a href="#">Olympus</a></li>
        <li><a href="#">Panasonic</a></li>
        <li><a href="#">Canon</a></li>
        <li><a href="#">Sony</a></li>
        <li><a href="#">Samsung </a></li>
        <li><a href="#">Nikon</a></li>
        <li><a href="#">Olympus</a></li>
        <li><a href="#">Panasonic</a></li>
    </ul>
    <div class="showmore">
        <a href="more.html"><span>Show all brands</span></a>
    </div>
</div>
</body>
</html>
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