computed.html

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>computed</title>
		<script src="https://cdn.staticfile.org/vue/2.2.2/vue.min.js"></script>
	</head>
	<body>
		<div id="app">
			<p>"源message"{{message}}</p>
			<p>"计算首次调用"{{reversedMessage}}</p>
			<p>"方法首次调用"{{resver()}}</p>
			<p>"计算二次调用"{{reversedMessage}}</p>
			<p>"方法二次调用"{{resver()}}</p>
		</div>
		<script>
			var i = 1;
			new Vue({
				el: "#app",
				data: {
					message: "Vue"
				},
				computed: {
					reversedMessage: function() {
						i += 1;
						return this.message.split("").reverse().join("") + i;
					}
				},
				methods: {
					resver: function() {
						i += 1;
						return this.message.split("").reverse().join("") + i;
					}
				}
			})
		</script>
	</body>
</html>