Individual skill

defer-async

Use when reviewing templates, rendered HTML, or shared components related to Load scripts with defer, async, or type=module. Validate the final browser-facing markup, not just the source framework abstraction.

skills/defer-async/SKILL.md

Read pinned source

Source commit e8d14d049010e2ce25afcd5e8609dfcbbe63e47e

What was checked

Matches the observed repository HEAD: Yes
Scanner rules are current: Yes
Repository scan complete: No
Skill scan complete: No
Observed behavior: Network or broad shell
Last checked: Nov 9, 2026

These are observations at the recorded commit, not a guarantee of safety. Review the source before running it.

Install this skill

Choose an agent in your Stack or copy a command below. Commands fetch the pinned commit and copy only this skill directory. Existing destinations are refused. Copying a command does not install anything.

An install command is unavailable: current rules, complete repository and skill scans, an eligible behavior level and a permitted license are required.

Repository context

Repository stars (not skill ratings): 74,698
Repository last updated: Oct 31, 2026
License: MIT

Observed agent integration: No specific integration evidence. Standard SKILL.md installation does not imply verified compatibility.

frontend Repository topic
front-end-development Repository topic
front-end-developer-tool Repository topic
guidelines Repository topic
checklist Repository topic
reference Repository topic
web-development Repository topic
html Repository topic
css Repository topic
javascript Repository topic
engineering Derived category

Files and excerpt

File metadata and permitted, redacted excerpts come from the recorded scan. Source links are pinned to that commit.

Browse files

SKILL.mdcore · 1,977 bytes
SKILL.mdcore · 1,977 bytes
references/rule.mddoc · 4,342 bytes

Read excerpt


# Load scripts with defer, async, or type=module

A plain &lt;script&gt; tag in the document head blocks all HTML parsing until the script downloads, parses, and executes. On a slow network this can add seconds of white-screen time before any content renders. defer and async allow the browser to continue parsing HTML while the script downloads, reducing Time to First Contentful Paint dramatically.

## Quick Reference

- defer downloads in parallel and executes after HTML parsing, in order — use for most scripts
- async downloads in parallel and executes immediately when ready — use for independent scripts
- type=module always defers and enables ES module syntax
- Never place scripts in <head> without defer or async

## Check

Find all script tags in this HTML file. Flag any in the <head> without defer or async, and any at the bottom of <body> that could be in <head> with defer.