Script Loader: Prevent strict mode leaking into concatenated scripts#12271
Script Loader: Prevent strict mode leaking into concatenated scripts#12271itzmekhokan wants to merge 1 commit into
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Since [22294], `wp-includes/js/dist/hooks.js` is built with esbuild, whose output begins with a top-level `"use strict";` directive. When admin script concatenation is enabled, `load-scripts.php` appends the requested files one after another, with `wp-hooks` first in the chunk. That leading directive becomes the directive prologue for the whole concatenated file, forcing every legacy, non-strict script bundled afterwards (such as ThickBox) to run in strict mode. There, ThickBox's implicit global assignments throw `ReferenceError: imgLoader is not defined`, leaving the modal stuck on the overlay (for example when clicking "View details" on the Plugins screen). Begin the concatenated output with an empty statement so that a leading `"use strict";` is no longer the first statement and is evaluated as a harmless expression instead of enabling strict mode for the entire file. This restores the pre-7.0 behaviour, where concatenated admin scripts ran in sloppy mode, and fixes every non-strict bundled script at once rather than only the first implicit global that happens to throw. Fixes #65515.
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Fixes the WordPress 7.0 regression where ThickBox modals fail to open (e.g. "View details" on the Plugins screen), with the console error
ReferenceError: imgLoader is not defined.What the problem was:
"use strict";.wp-hooksfirst, so that directive becomes the directive prologue for the entire concatenated file, forcing strict mode on every script after it.imgLoader,imgPreloader,TB_WIDTH,ajaxContentW, ...), which throw ReferenceError in strict mode and abort the modal.What the fix does:
$out = ";\n";), so a leading"use strict";is no longer the first statement and is evaluated as a harmless expression instead of enabling strict mode for the whole file.Approach and why:
imgLoaderwould move the crash to the next implicit global on the same code path and leave every other bundled legacy script exposed.Trac ticket: https://core.trac.wordpress.org/ticket/65515
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