WP_Scripts

Last updated: February 13, 2026

Core class for registering and outputting JavaScript files.

Source: wp-includes/class-wp-scripts.php
Since: 2.1.0
Extends: WP_Dependencies

Properties

Public Properties

PropertyTypeSinceDescription
$base_urlstring2.6.0Base URL for scripts (trailing slash)
$content_urlstring2.8.0URL of wp-content directory
$default_versionstring2.6.0Default version string
$in_footerarray2.8.0Handles of scripts enqueued in footer
$concatstring2.8.0Handles to concatenate
$concat_versionstring2.8.0Deprecated (3.4.0)
$do_concatbool2.8.0Whether to concatenate
$print_htmlstring2.8.0HTML markup when concatenating
$print_codestring2.8.0Inline code when concatenating
$ext_handlesstring2.8.0External handles (unused in core)
$ext_versionstring2.8.0External versions (unused in core)
$default_dirsarray2.8.0Default script directories

Private Properties

PropertyTypeSinceDescription
$dependents_maparray6.3.0Cache of dependent handles
$delayed_strategiesstring[]6.3.0Valid delayed strategies (defer, async)

Methods

__construct()

Initializes the scripts object and fires initialization action.

php
public function __construct()

Since: 2.6.0

Hooks: Calls do_action_ref_array( 'wp_default_scripts', array( &$this ) )

init()

Fires the initialization action.

php
public function init(): void

Since: 3.4.0

Hooks:

php
do_action_ref_array( 'wp_default_scripts', array( &$this ) );

Prints scripts and their dependencies.

php
public function print_scripts(
    string|string[]|false $handles = false,
    int|false $group = false
): string[]

Since: 2.1.0

ParameterTypeDescription
$handlesstring|string[]|falseScripts to print (false = queue)
$groupint|falseGroup level or false

Returns: Handles of printed scripts.

Prints extra data attached to a script.

php
public function print_extra_script(
    string $handle,
    bool $display = true
): bool|string|void

Since: 3.3.0

ParameterTypeDescription
$handlestringScript handle
$displayboolPrint or return

Returns: Void if no data, script if $display true, true otherwise.

do_item()

Processes and outputs a single script.

php
public function do_item(
    string $handle,
    int|false $group = false
): bool

Since: 2.6.0

ParameterTypeDescription
$handlestringScript handle
$groupint|falseGroup level

Returns: true on success, false on failure.

Behavior:

  • Skips scripts with conditional comments
  • Handles defer/async strategies
  • Outputs translations before script
  • Applies script_loader_src and script_loader_tag filters

add_inline_script()

Adds inline JavaScript to a registered script.

php
public function add_inline_script(
    string $handle,
    string $data,
    string $position = 'after'
): bool

Since: 4.5.0

ParameterTypeDescription
$handlestringScript handle (lowercase)
$datastringJavaScript code
$positionstring'before' or 'after'

Returns: true on success, false on failure.

get_inline_script_data()

Gets inline script data without tags.

php
public function get_inline_script_data(
    string $handle,
    string $position = 'after'
): string

Since: 6.3.0

Returns: Inline script code or empty string.

get_inline_script_tag()

Gets inline script with <script> tags.

php
public function get_inline_script_tag(
    string $handle,
    string $position = 'after'
): string

Since: 6.3.0

Returns: Complete script tag or empty string.

localize()

Attaches localization data to a script.

php
public function localize(
    string $handle,
    string $object_name,
    array $l10n
): bool

Since: 2.1.0

ParameterTypeDescription
$handlestringScript handle
$object_namestringJavaScript variable name
$l10narrayData to localize

Returns: true on success.

Note: For jquery handle, automatically uses jquery-core.

set_group()

Sets the group level for a script handle.

php
public function set_group(
    string $handle,
    bool $recursion,
    int|false $group = false
): bool

Since: 2.8.0

Returns: true if not already in a lower group.

set_translations()

Sets translation text domain for a script.

php
public function set_translations(
    string $handle,
    string $domain = 'default',
    string $path = ''
): bool

Since: 5.0.0

ParameterTypeDescription
$handlestringScript handle
$domainstringText domain
$pathstringPath to translation files

Returns: true on success, false if handle not registered.

Note: Automatically adds wp-i18n as a dependency.

Outputs translation strings for a script.

php
public function print_translations(
    string $handle,
    bool $display = true
): string|false

Since: 5.0.0

Returns: Translation script or false if none.

all_deps()

Determines all dependencies for given handles.

php
public function all_deps(
    string|string[] $handles,
    bool $recursion = false,
    int|false $group = false
): bool

Since: 2.1.0

Hooks:

php
$this->to_do = apply_filters( 'print_scripts_array', $this->to_do );

do_head_items()

Processes scripts for the head group.

php
public function do_head_items(): string[]

Since: 2.8.0

Returns: Handles of processed scripts.

Processes scripts for the footer group.

php
public function do_footer_items(): string[]

Since: 2.8.0

Returns: Handles of processed scripts.

in_default_dir()

Checks if source is in a default directory.

php
public function in_default_dir( string $src ): bool

Since: 2.8.0

Returns: true if in default directory.

add_data()

Adds data to a registered script with validation.

php
public function add_data(
    string $handle,
    string $key,
    mixed $value
): bool

Since: 6.3.0

Validated Keys:

  • strategy — Must be 'defer' or 'async'
  • fetchpriority — Must be 'auto', 'low', or 'high'
  • conditional — Clears dependencies

Returns: true on success, false on failure or invalid value.

reset()

Resets concatenation properties.

php
public function reset(): void

Since: 2.8.0

Clears: do_concat, print_code, concat, concat_version, print_html, ext_version, ext_handles

get_dependency_warning_message()

Gets localized warning message for missing dependencies.

php
protected function get_dependency_warning_message(
    string $handle,
    string[] $missing_dependency_handles
): string

Since: 6.9.1

Private Methods

Checks if all dependents of a handle are in footer group.

php
private function are_all_dependents_in_footer( string $handle ): bool

Since: 6.4.0

get_dependents()

Gets all scripts that depend on a handle.

php
private function get_dependents( string $handle ): string[]

Since: 6.3.0

is_delayed_strategy()

Checks if strategy is defer or async.

php
private function is_delayed_strategy( mixed $strategy ): bool

Since: 6.3.0

is_valid_fetchpriority()

Validates fetchpriority value.

php
private function is_valid_fetchpriority( mixed $priority ): bool

Since: 6.9.0

Valid values: 'auto', 'low', 'high'

get_eligible_loading_strategy()

Determines the best loading strategy for a script.

php
private function get_eligible_loading_strategy( string $handle ): string

Since: 6.3.0

Returns: 'async', 'defer', or empty string.

Logic:

  • async can fallback to defer
  • defer cannot use async
  • Scripts with after inline scripts cannot be delayed

filter_eligible_strategies()

Filters eligible strategies based on dependents.

php
private function filter_eligible_strategies(
    string $handle,
    ?string[] $eligible_strategies = null,
    array $checked = array(),
    array &$stored_results = array()
): string[]

Since: 6.3.0

get_highest_fetchpriority_with_dependents()

Gets highest fetchpriority considering dependents.

php
private function get_highest_fetchpriority_with_dependents(
    string $handle,
    array $checked = array(),
    array &$stored_results = array()
): ?string

Since: 6.9.0

Priority order: low < auto < high

has_inline_script()

Checks if handle has inline scripts.

php
private function has_inline_script(
    string $handle,
    ?string $position = null
): bool

Since: 6.3.0

Deprecated Methods

php
public function print_scripts_l10n( string $handle, bool $display = true )

Deprecated: 3.3.0 — Use print_extra_script().

php
public function print_inline_script( string $handle, string $position = 'after', bool $display = true )

Deprecated: 6.3.0 — Use get_inline_script_data() or get_inline_script_tag().

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