Async/Defer Script Advisor
Guide for script loading with async vs defer vs module, including a decision tree, impact analysis, and code generation
Loading Strategy Comparison
| Strategy | Blocks Parsing | Execution Order | DOM Ready | Best For |
|---|---|---|---|---|
| (none) | Yes | In order | Before | Critical render-blocking scripts |
| async | No | Any order | Maybe | Independent scripts (analytics) |
| defer | No | In order | Before DOMContentLoaded | Scripts needing DOM + order |
| type="module" | No (deferred) | In order | Before DOMContentLoaded | ES modules |
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