javascript:
(function() {

	var limit = 250;
	$(".comment").each(function(i, e) {
		if (e.innerText.length > limit) {
			$(e).addClass("commentlong")
			$('<a class="hidecomment">展開</a>').insertAfter(e);
			var short = $('<span class="comment commentshort"></span>');
			$(short).text(e.innerText.substr(0, limit + 1) + "..." + e.innerText.substr(-1));
			$(short).insertAfter(e);
			$(e.parentElement).find(">.commentlong").hide();
		}
	});

	$(".hidecomment").click(function(e) {
		if ($(e.target.parentElement).find(">.commentlong").is(":visible")) {
			$(e.target.parentElement).find(">.commentlong").hide();
			$(e.target.parentElement).find(">.commentshort").show();
			$(e.target.parentElement).find(">.hidecomment").text("展開");
		} else {
			$(e.target.parentElement).find(">.commentlong").show();
			$(e.target.parentElement).find(">.commentshort").hide();
			$(e.target.parentElement).find(">.hidecomment").text("收合");
		}
	});

})();

javascript:
(function() {

	var limit = 250;
	$(".comment").each(function(i, e) {
		if (e.innerText.length > limit) {
			$(e).addClass("commentlong")
			$('<a class="hidecomment">展開</a>').insertAfter(e);
			var short = $('<span class="comment comment--without-parentheses commentshort"></span>');
			$(short).text(e.innerText.substr(0, limit + 1) + "..." + e.innerText.substr(-1));
			$(short).insertAfter(e);
			$(e.parentElement).find(">.commentlong").hide();
		}
	});

	$(".hidecomment").click(function(e) {
		if ($(e.target.parentElement).find(">.commentlong").is(":visible")) {
			$(e.target.parentElement).find(">.commentlong").hide();
			$(e.target.parentElement).find(">.commentshort").show();
			$(e.target.parentElement).find(">.hidecomment").text("展開");
		} else {
			$(e.target.parentElement).find(">.commentlong").show();
			$(e.target.parentElement).find(">.commentshort").hide();
			$(e.target.parentElement).find(">.hidecomment").text("收合");
		}
	});

})();

Add class