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HTML/CSSBeginner#html#forms
HTML/CSSIntermediate#html#performance#scripts
What is the difference between <script>, <script async>, and <script defer>?
Plain <script> blocks HTML parsing while it downloads and executes. async downloads in parallel and executes as soon as ready (out of order), still blocking parsing briefly. defer downloads in parallel but executes only after parsing completes, in document order — best for most scripts.
Example
<script src="analytics.js" async></script> <script src="app.js" defer></script>