Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Clarify boolean attribute behaviour is unchanged #31

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Clarify boolean attribute behaviour is unchanged #31

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 3 additions & 7 deletions src/breaking-changes/attribute-coercion.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,16 +5,12 @@ badges:

# Attribute Coercion Behavior <MigrationBadges :badges="$frontmatter.badges" />

::: info Info
This is a low-level internal API change and does not affect most developers.
:::

## Overview

Here is a high level summary of the changes:

- Drop the internal concept of enumerated attributes and treat those attributes the same as normal non-boolean attributes
- **BREAKING**: No longer removes attribute if the value is boolean `false`. Instead, it's set as attr="false". To remove the attribute, use `null` or `undefined`.
- **BREAKING**: No longer removes non-boolean attribute if the value is boolean `false`. Instead, it's set as attr="false". To remove the attribute, use `null` or `undefined`. Handling of [boolean attributes](https://meiert.com/en/blog/boolean-attributes-of-html/) remain untouched.

For more information, read on!

Expand All @@ -30,7 +26,7 @@ In 2.x, we had the following strategies for coercing `v-bind` values:

- For other attributes, we remove "falsy" values (`undefined`, `null`, or `false`) and set other values as-is (see [here](https://github.com/vuejs/vue/blob/bad3c326a3f8b8e0d3bcf07917dc0adf97c32351/src/platforms/web/runtime/modules/attrs.js#L92-L113)).

The following table describes how Vue coerce "enumerated attributes" differently with normal non-boolean attributes:
The following table describes how Vue coerces "enumerated attributes" differently with normal non-boolean attributes:

| Binding expression | `foo` <sup>normal</sup> | `draggable` <sup>enumerated</sup> |
| ------------------- | ----------------------- | --------------------------------- |
Expand Down Expand Up @@ -91,7 +87,7 @@ In 2.x, invalid values were coerced to `'true'` for enumerated attributes. This

### Coercing `false` to `'false'` instead of removing the attribute

In 3.x, `null` or `undefined` should be used to explicitly remove an attribute.
In 3.x, `null` or `undefined` should be used to explicitly remove a non-boolean attribute.

### Comparison between 2.x & 3.x behavior

Expand Down