console 命令行工具 X clear
console
<html>
    <head>
        <script src="https://cdn.jsdelivr.net/npm/vue@2.7.8/dist/vue.js"></script>
    </head>
    <body>
    <div id="app">
        <h1>{{ message }}</h1>
        <p>{{ getSum() }}</p>
        <button @click="numIncrease">Num ++</button>
    </div>
    <script>
        var vm = new Vue({
            el: '#app',
            data: {
                message: 'hello lee',
                number: 0,
                number1: 56,
            },
            methods: {
                numIncrease() {
                    this.number++
                },
                // 测试方法是不是实时生效
                getSum() {
                    return this.number + this.number1
                }
            }
        })
    </script>
    </body>
</html>