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Find scripts without async or defer on a page

harmlessImages and performancedebian, ubuntu
Adjust the values, the command updates live
user@server
curl -s https://example.com/ | tr '\n' ' ' | grep -oiE '<script[^>]*src=[^>]*>' | grep -viE 'async|defer|type=.?module'

Shows every <script src> without async, defer or type="module". Such scripts stop the browser from parsing until they are loaded and executed, which delays First Contentful Paint and LCP. Matches in the <head> are especially critical.

Note: Scripts at the end of <body> hardly block, but they are listed too. Scripts that depend on jQuery cannot always be switched to defer safely.

Also searched as

  • find render-blocking resources
  • javascript without defer
  • eliminate render-blocking scripts pagespeed
  • scripts in head slow down page

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Compare the response time of a PHP page with a static file

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Find unminified CSS and JS files

$find /var/www/vhosts/example.com/httpdocs/wp-content -type f \( -name '*.css' -o -name '*.js' \) ! -name '*.min.*' -size +20k -exec sh -c 'echo "$(wc -l < "$1") $1"' sh {} \; | awk -v n=200 '$1 > n' | sort -rn | head -30
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