♻️ (blaze/attrs): optimize attribute updates by caching last values

[wreiske]

This is an experimental PR for some performance improvements.

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22e0df1

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6d849c8

[jankapunkt]

Thanks a lot for this improvement! I will thoroughly test this using BlazeUI once we have a alpha release for this, because in BlazeUI I am defining components only around attributes so I can easily tell you if things are breaking.

As I commented, please add more inline docs (Blaze is already missing inline docs a lot, so we need a higher comment to code ratio).

One concern that is left is, whether tests deeply enough covered that caching won't break reactivity and various contexts (with, async, each, helpers etc.) where attributes can play a role.

[wreiske]

[Copilot]

Pull Request Overview

This PR implements performance optimizations for Blaze's attribute system by introducing caching mechanisms to reduce redundant DOM operations. The main focus is optimizing attribute updates by tracking the last known values and only performing DOM updates when values actually change.

• Adds URL protocol caching with LRU eviction to avoid repeated DOM operations for URL validation
• Implements _lastValues cache in ElementAttributesUpdater to prevent redundant attribute updates
• Updates test application dependencies to Meteor 3.3-beta.1 and enables modern bundle mode

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/blaze/attrs.js	Core optimization implementation with protocol caching and last-values tracking
tests/benchmark_getUrlProtocol.html	Benchmark suite for measuring URL protocol detection performance improvements
tests/benchmark_ElementAttributesUpdater.html	Benchmark suite for measuring attribute update performance improvements
test-app/package.json	Enables modern bundle mode for the test application
test-app/.meteor/versions	Updates Meteor packages to 3.3-beta.1 versions
test-app/.meteor/release	Updates Meteor version to 3.3-beta.1
test-app/.meteor/packages	Updates package version references for compatibility

Comments suppressed due to low confidence (2)

packages/blaze/attrs.js:139

• [nitpick] The shouldUpdate logic is complex and spans multiple lines. Consider extracting this into a helper function like hasValueChanged(last, value) to improve readability and testability.

    const currentAttrsMap = currentAttrString ? this.parseValue(currentAttrString) : new OrderedDict();

tests/benchmark_getUrlProtocol.html:174

• Using Date.now() for generating unique IDs could cause collisions if multiple elements are created in rapid succession. Consider using a counter or more robust unique ID generation.

    console.log(`Average Cached Time: ${avgCachedTime.toFixed(3)} ms`);