JavaScript File Size Too Large

Checks for JavaScript files that exceed recommended size limits

Rule ID	perf/js-file-size
Category	Performance
Scope	Site-wide
Severity	error
Weight	7/10

Solution

Large JavaScript files block the main thread and delay interactivity. Code-split bundles into smaller chunks, tree-shake unused exports, lazy-load non-critical scripts, and defer or async load third-party scripts. Use dynamic imports for route-based splitting.

Options

This rule supports the following configuration options:

Option	Type	Default	Description
warn_bytes	number	256000 (250KB)	Byte size to trigger warning
error_bytes	number	1048576 (1MB)	Byte size to trigger error

Configuration Example

[rules."perf/js-file-size"]
warn_bytes = 256000
error_bytes = 1048576

Enable / Disable

Disable this rule

[rules]
disable = ["perf/js-file-size"]

Disable all Performance rules

[rules]
disable = ["perf/*"]

Enable only this rule

[rules]
enable = ["perf/js-file-size"]
disable = ["*"]