doc bug ? #10349

startjava · 2024-02-17T00:57:22Z

startjava
Feb 17, 2024

https://vuejs.org/guide/essentials/computed.html#writable-computed

Computed properties are by default getter-only. If you attempt to assign a new value to a computed property, you will receive a runtime warning.

but bottom my code.

html：

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <div id="mydiv">
        </div>
        <script type="module" src="writable_computed_1.js"></script>
    </body>
</html>

js：

import {createApp, reactive, computed} from 'vue'

createApp({
    setup() {
        const author = reactive({
            name: 'John Doe',
            books: [
                'Vue 2 - Advanced Guide',
                'Vue 3 - Basic Guide',
                'Vue 4 - The Mystery'
            ]
        })

        // 一个计算属性 ref
        let publishedBooksMessage = computed(() => {
            return author.books.length > 0 ? 'Yes' : 'No'
        });

        publishedBooksMessage = "abc";

        return {}
    }
}).mount("#mydiv");

but run result no warning in F12。

redblobgames · 2024-02-17T02:10:57Z

redblobgames
Feb 17, 2024

I think this is not a doc bug. The doc is referring to assigning a new value to the computed property, like publishedBooksMessage.value = "abc".

This code is not assigning a new value to the computed property. It is ignoring the computed property, and assigning a new value to the variable publishedBooksMessage = "abc".

To avoid this kind of error, the tutorial and guide in the docs always use const for ref, reactive, and computed. I think the tutorial and guide could be better about reminding people to use const instead of let.

0 replies

startjava · 2024-02-17T03:39:57Z

startjava
Feb 17, 2024
Author

thank @redblobgames

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Vue

doc bug ? #10349

startjava Feb 17, 2024

Replies: 2 comments

redblobgames Feb 17, 2024

startjava Feb 17, 2024 Author

startjava
Feb 17, 2024

redblobgames
Feb 17, 2024

startjava
Feb 17, 2024
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