wp-includes/script-loader.php:223Returns contents of an inline script used in appending polyfill scripts for browsers which fail the provided tests. The provided array is a mapping from a condition to verify feature support to its polyfill script handle.
$scriptsWP_Scripts$testsstring[]stringOne hook fires while wp_get_script_polyfill() runs, in this order:
Filters the script loader source.
function wp_get_script_polyfill( $scripts, $tests ) { $polyfill = ''; foreach ( $tests as $test => $handle ) { if ( ! array_key_exists( $handle, $scripts->registered ) ) { continue; } $src = $scripts->registered[ $handle ]->src; $ver = $scripts->registered[ $handle ]->ver; if ( ! preg_match( '|^(https?:)?//|', $src ) && ! ( $scripts->content_url && str_starts_with( $src, $scripts->content_url ) ) ) { $src = $scripts->base_url . $src; } if ( ! empty( $ver ) ) { $src = add_query_arg( 'ver', $ver, $src ); } /** This filter is documented in wp-includes/class-wp-scripts.php */ $src = esc_url( apply_filters( 'script_loader_src', $src, $handle ) ); if ( ! $src ) { continue; } $polyfill .= ( // Test presence of feature... '( ' . $test . ' ) || ' . /* * ...appending polyfill on any failures. Cautious viewers may balk * at the `document.write`. Its caveat of synchronous mid-stream * blocking write is exactly the behavior we need though. */ 'document.write( \'<script src="' . $src . '"></scr\' + \'ipt>\' );' ); } return $polyfill;}Introduced in 5.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/script-loader.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.