104 lines
2.5 KiB
Markdown
104 lines
2.5 KiB
Markdown
# @vue/ref-transform
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> ⚠️ This is experimental and currently only provided for testing and feedback. It may break during patches or even be removed. Use at your own risk!
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>
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> Follow https://github.com/vuejs/rfcs/discussions/369 for details and updates.
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## Basic Rules
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- `$()` to turn refs into reative variables
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- `$$()` to access the original refs from reative variables
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```js
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import { ref, watch } from 'vue'
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// bind ref as a variable
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let count = $(ref(0))
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// no need for .value
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console.log(count)
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// get the actual ref
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watch($$(count), c => console.log(`count changed to ${c}`))
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// assignments are reactive
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count++
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```
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### Shorthands
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A few commonly used APIs have shorthands (which also removes the need to import them):
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- `$(ref(0))` -> `$ref(0)`
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- `$(computed(() => 123))` -> `$computed(() => 123)`
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- `$(shallowRef({}))` -> `$shallowRef({})`
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## API
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This package is the lower-level transform that can be used standalone. Higher-level tooling (e.g. `@vitejs/plugin-vue` and `vue-loader`) will provide integration via options.
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### `shouldTransform`
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Can be used to do a cheap check to determine whether full transform should be performed.
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```js
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import { shouldTransform } from '@vue/ref-transform'
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shouldTransform(`let a = ref(0)`) // false
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shouldTransform(`let a = $ref(0)`) // true
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```
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### `transform`
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```js
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import { transform } from '@vue/ref-transform'
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const src = `let a = $ref(0); a++`
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const {
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code, // import { ref as _ref } from 'vue'; let a = (ref(0)); a.value++"
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map
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} = transform(src, {
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filename: 'foo.ts',
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sourceMap: true,
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// @babel/parser plugins to enable.
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// 'typescript' and 'jsx' will be auto-inferred from filename if provided,
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// so in most cases explicit parserPlugins are not necessary
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parserPlugins: [
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/* ... */
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]
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})
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```
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**Options**
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```ts
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interface RefTransformOptions {
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filename?: string
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sourceMap?: boolean // default: false
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parserPlugins?: ParserPlugin[]
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importHelpersFrom?: string // default: "vue"
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}
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```
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### `transformAST`
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Transform with an existing Babel AST + MagicString instance. This is used internally by `@vue/compiler-sfc` to avoid double parse/transform cost.
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```js
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import { transformAST } from '@vue/ref-transform'
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import { parse } from '@babel/parser'
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import MagicString from 'magic-string'
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const src = `let a = $ref(0); a++`
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const ast = parse(src, { sourceType: 'module' })
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const s = new MagicString(src)
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const {
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rootRefs, // ['a']
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importedHelpers // ['ref']
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} = transformAST(ast, s)
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console.log(s.toString()) // let a = _ref(0); a.value++
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```
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