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.

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

Improve SSR hydration performance #6204

Merged
merged 2 commits into from
Apr 21, 2021
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
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
1 change: 1 addition & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

## Unreleased

* Avoid recreating DOM elements during hydration ([#6204](https://github.com/sveltejs/svelte/pull/6204))
* Add missing function overload for `derived` to allow explicitly setting an initial value for non-async derived stores ([#6172](https://github.com/sveltejs/svelte/pull/6172))
* Pass full markup source to script/style preprocessors ([#6169](https://github.com/sveltejs/svelte/pull/6169))

Expand Down
4 changes: 3 additions & 1 deletion src/runtime/internal/Component.ts
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
import { add_render_callback, flush, schedule_update, dirty_components } from './scheduler';
import { current_component, set_current_component } from './lifecycle';
import { blank_object, is_empty, is_function, run, run_all, noop } from './utils';
import { children, detach } from './dom';
import { children, detach, start_hydrating, end_hydrating } from './dom';
import { transition_in } from './transitions';

interface Fragment {
Expand Down Expand Up @@ -150,6 +150,7 @@ export function init(component, options, instance, create_fragment, not_equal, p

if (options.target) {
if (options.hydrate) {
start_hydrating();
const nodes = children(options.target);
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
$$.fragment && $$.fragment!.l(nodes);
Expand All @@ -161,6 +162,7 @@ export function init(component, options, instance, create_fragment, not_equal, p

if (options.intro) transition_in(component.$$.fragment);
mount_component(component, options.target, options.anchor, options.customElement);
end_hydrating();
flush();
}

Expand Down
50 changes: 43 additions & 7 deletions src/runtime/internal/dom.ts
Original file line number Diff line number Diff line change
@@ -1,15 +1,47 @@
import { has_prop } from './utils';

// Track which nodes are claimed during hydration. Unclaimed nodes can then be removed from the DOM
// at the end of hydration without touching the remaining nodes.
let is_hydrating = false;
const nodes_to_detach = new Set<Node>();

export function start_hydrating() {
is_hydrating = true;
}
export function end_hydrating() {
is_hydrating = false;

for (const node of nodes_to_detach) {
node.parentNode.removeChild(node);
}

nodes_to_detach.clear();
}

export function append(target: Node, node: Node) {
target.appendChild(node);
if (is_hydrating) {
nodes_to_detach.delete(node);
}
if (node.parentNode !== target) {
target.appendChild(node);
}
}

export function insert(target: Node, node: Node, anchor?: Node) {
target.insertBefore(node, anchor || null);
if (is_hydrating) {
nodes_to_detach.delete(node);
}
if (node.parentNode !== target || (anchor && node.nextSibling !== anchor)) {
target.insertBefore(node, anchor || null);
}
}

export function detach(node: Node) {
node.parentNode.removeChild(node);
if (is_hydrating) {
nodes_to_detach.add(node);
} else if (node.parentNode) {
node.parentNode.removeChild(node);
}
}

export function destroy_each(iterations, detaching) {
Expand Down Expand Up @@ -154,8 +186,9 @@ export function children(element) {
}

export function claim_element(nodes, name, attributes, svg) {
for (let i = 0; i < nodes.length; i += 1) {
const node = nodes[i];
while (nodes.length > 0) {
const node = nodes.shift();

if (node.nodeName === name) {
let j = 0;
const remove = [];
Expand All @@ -168,7 +201,10 @@ export function claim_element(nodes, name, attributes, svg) {
for (let k = 0; k < remove.length; k++) {
node.removeAttribute(remove[k]);
}
return nodes.splice(i, 1)[0];

return node;
} else {
detach(node);
}
}

Expand All @@ -180,7 +216,7 @@ export function claim_text(nodes, data) {
const node = nodes[i];
if (node.nodeType === 3) {
node.data = '' + data;
return nodes.splice(i, 1)[0];
return nodes.shift();
benmccann marked this conversation as resolved.
Show resolved Hide resolved
}
}

Expand Down