【vue】computed计算属性

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <h2>add:{{add()}}</h2>
        <h2>add:{{add()}}</h2>

        <h2>sum:{{sum}}</h2>
        <h2>sum:{{sum}}</h2>

        x<input type="text" v-model.number="data.x"><br>
        y<input type="text" v-model.number="data.y">

    </div>

    <script type="module">
        import { createApp, reactive, computed } from './vue.esm-browser.js'
        createApp({
            setup() {
                const data = reactive({
                    x: 12,
                    y: 25
                })
                //无缓存，每次调用都会重新计算
                let add = () => {
                    console.log("add")
                    return data.x + data.y
                }
                //有缓存，相同结果不需要重复计算
                const sum = computed(() => {
                    console.log("sum")
                    return data.x + data.y
                })
                return {
                    data,
                    add,
                    sum
                }
            }
        }).mount("#app")
    </script>
</body>

</html>

调用了两次add，一次sum

参考

https://www.bilibili.com/video/BV1nV411Q7RX