From 85871d74bbb3ade10c03becfa939409088495e9e Mon Sep 17 00:00:00 2001 From: Rich Harris Date: Wed, 21 Aug 2024 12:51:08 -0400 Subject: [PATCH] Revert "breaking: remove `$state.link` callback (#12942)" This reverts commit 0b51ff04b045d2fa53c0b5a365f3d3a2c0541aa5. --- .changeset/sharp-foxes-whisper.md | 5 --- documentation/docs/03-runes/01-state.md | 18 +++++++++ packages/svelte/src/ambient.d.ts | 2 +- .../client/visitors/VariableDeclaration.js | 6 ++- .../src/internal/client/reactivity/sources.js | 19 +++++++++- .../samples/state-link-callback/_config.js | 38 +++++++++++++++++++ .../samples/state-link-callback/main.svelte | 12 ++++++ packages/svelte/types/index.d.ts | 2 +- .../routes/docs/content/01-api/02-runes.md | 18 +++++++++ 9 files changed, 110 insertions(+), 10 deletions(-) delete mode 100644 .changeset/sharp-foxes-whisper.md create mode 100644 packages/svelte/tests/runtime-runes/samples/state-link-callback/_config.js create mode 100644 packages/svelte/tests/runtime-runes/samples/state-link-callback/main.svelte diff --git a/.changeset/sharp-foxes-whisper.md b/.changeset/sharp-foxes-whisper.md deleted file mode 100644 index 553ae1bd6d00..000000000000 --- a/.changeset/sharp-foxes-whisper.md +++ /dev/null @@ -1,5 +0,0 @@ ---- -'svelte': patch ---- - -breaking: remove callback from `$state.link` diff --git a/documentation/docs/03-runes/01-state.md b/documentation/docs/03-runes/01-state.md index 8d78e6c73ea1..35dc2f357db5 100644 --- a/documentation/docs/03-runes/01-state.md +++ b/documentation/docs/03-runes/01-state.md @@ -89,6 +89,24 @@ console.log(a, b); // 3, 3 As with `$state`, if `$state.link` is passed a plain object or array it will be made deeply reactive. If passed an existing state proxy it will be reused, meaning that mutating the linked state will mutate the original. To clone a state proxy, you can use [`$state.snapshot`](#$state-snapshot). +If you pass a callback to `$state.link`, changes to the input value will invoke the callback rather than updating the linked state, allowing you to choose whether to (for example) preserve or discard local changes, or merge incoming changes with local ones: + +```js +let { stuff } = $props(); + +let incoming = $state(); +let hasUnsavedChanges = $state(false); + +let current = $state.link({ ...stuff }, (stuff) => { + if (hasUnsavedChanges) { + incoming = stuff; + } else { + incoming = null; + current = stuff; + } +}); +``` + ## `$state.raw` State declared with `$state.raw` cannot be mutated; it can only be _reassigned_. In other words, rather than assigning to a property of an object, or using an array method like `push`, replace the object or array altogether if you'd like to update it: diff --git a/packages/svelte/src/ambient.d.ts b/packages/svelte/src/ambient.d.ts index a84085fd5a70..e58b2c5aa5a5 100644 --- a/packages/svelte/src/ambient.d.ts +++ b/packages/svelte/src/ambient.d.ts @@ -148,7 +148,7 @@ declare namespace $state { * * @param value The linked value */ - export function link(value: T): T; + export function link(value: T, callback?: (value: T) => void): T; export function raw(initial: T): T; export function raw(): T | undefined; diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/VariableDeclaration.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/VariableDeclaration.js index 84713f73ca72..2c1db714ca72 100644 --- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/VariableDeclaration.js +++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/VariableDeclaration.js @@ -131,7 +131,11 @@ export function VariableDeclaration(node, context) { } if (rune === '$state.link') { - value = b.call('$.source_link', b.thunk(value)); + value = b.call( + '$.source_link', + b.thunk(value), + args.length === 2 && /** @type {Expression} */ (context.visit(args[1])) + ); } else if (is_state_source(binding, context.state.analysis)) { value = b.call('$.source', value); } diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js index edfa8806e838..d0c6441040c2 100644 --- a/packages/svelte/src/internal/client/reactivity/sources.js +++ b/packages/svelte/src/internal/client/reactivity/sources.js @@ -49,10 +49,12 @@ export function source(v) { /** * @template V * @param {() => V} get_value + * @param {(value: V) => void} [callback] * @returns {(value?: V) => V} */ -export function source_link(get_value) { +export function source_link(get_value, callback) { var was_local = false; + var init = false; var local_source = source(/** @type {V} */ (undefined)); var linked_derived = derived(() => { @@ -75,7 +77,20 @@ export function source_link(get_value) { return value; } - return (local_source.v = get(linked_derived)); + var linked_value = get(linked_derived); + + if (init) { + if (callback !== undefined) { + untrack(() => callback(linked_value)); + return local_source.v; + } + } else { + init = true; + } + + local_source.v = linked_value; + + return linked_value; }; } diff --git a/packages/svelte/tests/runtime-runes/samples/state-link-callback/_config.js b/packages/svelte/tests/runtime-runes/samples/state-link-callback/_config.js new file mode 100644 index 000000000000..bb56464ec1ed --- /dev/null +++ b/packages/svelte/tests/runtime-runes/samples/state-link-callback/_config.js @@ -0,0 +1,38 @@ +import { flushSync } from 'svelte'; +import { test } from '../../test'; + +export default test({ + html: ``, + + test({ assert, target }) { + const [btn1, btn2, btn3] = target.querySelectorAll('button'); + + flushSync(() => btn1.click()); + assert.htmlEqual( + target.innerHTML, + `` + ); + + flushSync(() => btn2.click()); + assert.htmlEqual( + target.innerHTML, + `` + ); + + flushSync(() => btn3.click()); + assert.htmlEqual(target.innerHTML, ``); + + flushSync(() => btn1.click()); + assert.htmlEqual(target.innerHTML, ``); + + flushSync(() => btn1.click()); + assert.htmlEqual(target.innerHTML, ``); + + flushSync(() => btn1.click()); + flushSync(() => btn3.click()); + assert.htmlEqual( + target.innerHTML, + `` + ); + } +}); diff --git a/packages/svelte/tests/runtime-runes/samples/state-link-callback/main.svelte b/packages/svelte/tests/runtime-runes/samples/state-link-callback/main.svelte new file mode 100644 index 000000000000..3b52359d05d4 --- /dev/null +++ b/packages/svelte/tests/runtime-runes/samples/state-link-callback/main.svelte @@ -0,0 +1,12 @@ + + + + + diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts index 6f9828375a0b..35b4e60f4598 100644 --- a/packages/svelte/types/index.d.ts +++ b/packages/svelte/types/index.d.ts @@ -2937,7 +2937,7 @@ declare namespace $state { * * @param value The linked value */ - export function link(value: T): T; + export function link(value: T, callback?: (value: T) => void): T; export function raw(initial: T): T; export function raw(): T | undefined; diff --git a/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md b/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md index 5fbed65a09ee..665d522815f8 100644 --- a/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md +++ b/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md @@ -91,6 +91,24 @@ console.log(a, b); // 3, 3 As with `$state`, if `$state.link` is passed a plain object or array it will be made deeply reactive. If passed an existing state proxy it will be reused, meaning that mutating the linked state will mutate the original. To clone a state proxy, you can use [`$state.snapshot`](#$state-snapshot). +If you pass a callback to `$state.link`, changes to the input value will invoke the callback rather than updating the linked state, allowing you to choose whether to (for example) preserve or discard local changes, or merge incoming changes with local ones: + +```js +let { stuff } = $props(); + +let incoming = $state(); +let hasUnsavedChanges = $state(false); + +let current = $state.link({ ...stuff }, (stuff) => { + if (hasUnsavedChanges) { + incoming = stuff; + } else { + incoming = null; + current = stuff; + } +}); +``` + ## `$state.raw` State declared with `$state.raw` cannot be mutated; it can only be _reassigned_. In other words, rather than assigning to a property of an object, or using an array method like `push`, replace the object or array altogether if you'd like to update it: