Elementor: experiments and markup-changing features

For developers shipping a companion plugin / theme that adds widgets, dynamic tags, or frontend CSS/JS on top of Elementor. Elementor ships "experiments" (feature flags) under core/experiments/manager.php. Most are cosmetic, but two Performance experiments change the rendered HTML and are default-ON on new installs, so a modern addon must handle them or it silently breaks on a large share of sites.

Read this first — you cannot assume the state

Experiment state is per-site and three-valued (Default / Active / Inactive), and the effective default differs between fresh and upgraded installs. Never hardcode an assumption; detect at runtime:

if ( \Elementor\Plugin::$instance->experiments->is_feature_active( 'e_optimized_markup' ) ) {
    // adapt markup
}

Verified: Experiments\Manager::is_feature_active( $name, $check_dependencies = false ) at core/experiments/manager.php:257; actual state resolves to the user's explicit state unless it's Default, then the feature's default (manager.php get_feature_actual_state).

The two markup-changing experiments (both release_status => STABLE, tag "Performance", new_site.default_active => true) — verified manager.php:312-381:

Experiment	name	Default on NEW install (≥ ver)	What it changes
Inline Font Icons	e_font_icon_svg	ON (≥ 3.17.0)	Icons render as inline <svg>; Font Awesome + eicons CSS/fonts NOT loaded on frontend
Optimized Markup	e_optimized_markup	ON (≥ 3.30.0)	Removes inner wrapper HTML (.elementor-widget-container) from widgets to shrink the DOM

new_site.default_active => true means a site first installed at/after that version defaults the experiment ON. Sites upgraded from older versions may keep it OFF (e_optimized_markup / container have default => STATE_INACTIVE). So the SAME addon meets both states in the wild — which is exactly why you detect at runtime.

Misconception this skill corrects

"My widget's icons render fine in the Elementor editor, so my icon markup is correct."

The editor/preview is misleading. Icons_Manager only switches to inline SVG when not in edit/preview mode — verified includes/managers/icons.php:186 (is_font_icon_inline_svg() && ! is_edit_mode() && ! is_preview_mode()). So with Inline Font Icons ON, the editor still loads the icon fonts and hardcoded <i class="fas fa-star"> looks correct there — but on the frontend the Font Awesome CSS is absent and your hardcoded icon renders as an empty/broken glyph. Always test on the published frontend, and always emit icons through Icons_Manager::render_icon().

When to use this skill

• Building or reviewing a custom widget (its render() markup, wrapper structure, or icon output).
• Shipping frontend CSS/JS that targets Elementor's DOM (.elementor-widget-container, widget inner structure).
• Any addon that renders icons chosen via the ICONS control.
• Diagnosing "works on my site, breaks on the client's" icon/layout bugs — usually an experiment default difference.
• The diff references is_feature_active, has_widget_inner_wrapper, Icons_Manager, e_optimized_markup, or e_font_icon_svg.

Optimized Markup (e_optimized_markup)

The wrapper contract lives on the element base. Element_Base::has_widget_inner_wrapper() returns true by default — verified includes/base/element-base.php:1588. Widget_Base::render() prints the <div class="elementor-widget-container"> only when that method returns true (includes/base/widget-base.php:427), and the widget's frontend script-dependency group flips common → common-optimized based on it (widget-base.php:201).

Core widgets opt IN to the DOM reduction by overriding it — the canonical one-liner, e.g. includes/widgets/button.php:85 and Pro's modules/forms/widgets/form.php:45:

public function has_widget_inner_wrapper(): bool {
    return ! \Elementor\Plugin::$instance->experiments->is_feature_active( 'e_optimized_markup' );
}

What this means for YOUR addon:

• Your widget does NOT break by default. Since the base returns true, a widget that doesn't override the method keeps its .elementor-widget-container even when Optimized Markup is on. No action needed for correctness.
• Your CSS/JS targeting CORE (and Pro) widgets DOES break when Optimized Markup is on, because those widgets drop the wrapper. A selector like .elementor-widget-heading .elementor-widget-container h2 {} stops matching; el.querySelector('.elementor-widget-container') returns null. Target the widget wrapper (.elementor-widget-{name} / .elementor-element) or the content element directly, not the inner container.
• To let your widget participate in the DOM reduction, override has_widget_inner_wrapper() with the same one-liner — then make sure your own styles/scripts don't depend on .elementor-widget-container, and register a -optimized-aware style if needed.

Inline Font Icons (e_font_icon_svg)

When active on the frontend, Icons_Manager::render_font_icon() resolves the icon to an inline <svg> via the SVG data manager and returns it; otherwise it falls back to <i class="{icon value}"> which needs the font CSS — verified includes/managers/icons.php:309-341. The single rule:

// RIGHT — works in BOTH modes; emits <svg> when the experiment is on, <i> otherwise
\Elementor\Icons_Manager::render_icon(
    $settings['my_icon'],           // the ICONS control value: [ 'value' => ..., 'library' => ... ]
    [ 'aria-hidden' => 'true' ],
    'i'                             // wrapping tag; ignored for uploaded-SVG
);

• render_icon() (icons.php:354) → get_icon_html() (icons.php:67) handles uploaded SVGs (library === 'svg') AND font icons transparently. Use it for every icon your widget outputs.
• Do NOT hardcode <i class="fas fa-..."> or manually enqueue Font Awesome expecting it to be present — with the experiment on, Elementor deliberately does not load FA/eicons CSS on the frontend, so hardcoded markup renders broken.
• If you genuinely need the font CSS (rare, legacy markup you can't convert), Icons_Manager::enqueue_shim() exists, but the right fix is to route through render_icon().
• This experiment sets generator_tag => true, so its state is also observable in the <meta name="generator"> Elementor emits — handy for support triage.

Registering your OWN experiment (optional)

Addons can register experiments on the same system via the elementor/experiments/default-features-registered action — verified core/experiments/manager.php:433. Allowed add_feature() option keys (manager.php:1049): name, title, tag, tags, description, release_status, default, mutable, hidden, new_site, on_state_change, dependencies, generator_tag, messages, deprecated.

add_action( 'elementor/experiments/default-features-registered', function ( $experiments ): void {
    $experiments->add_feature( [
        'name'           => 'myplugin_new_renderer',
        'title'          => esc_html__( 'My Plugin: New Renderer', 'myplugin' ),
        'release_status' => \Elementor\Core\Experiments\Manager::RELEASE_STATUS_BETA,
        'default'        => \Elementor\Core\Experiments\Manager::STATE_INACTIVE,
    ] );
} );

// then gate behavior:
if ( \Elementor\Plugin::$instance->experiments->is_feature_active( 'myplugin_new_renderer' ) ) { /* ... */ }

Critical rules

• Detect, never assume. Plugin::$instance->experiments->is_feature_active( $name ) — the effective default differs between fresh and upgraded installs.
• Both markup experiments are STABLE and default-ON on new installs — treat "on" as the common case, not an edge case.
• Icons: always Icons_Manager::render_icon(). Never hardcode <i class="fa">; the editor hides the breakage because it still loads fonts in edit/preview mode.
• Optimized Markup: your widget keeps its wrapper by default (base returns true), so it won't break — but your CSS/JS against core/Pro widgets' .elementor-widget-container will. Don't target the inner container.
• To opt your widget into DOM reduction, override has_widget_inner_wrapper() with the core one-liner, and make your own styles wrapper-independent.
• Don't fight the experiment by force-enqueuing Font Awesome or re-adding wrappers globally — you reintroduce the DOM/asset cost the site owner opted out of and cause the exact third-party conflicts the experiment warns about.

Common mistakes

// WRONG — hardcoded font icon; broken on frontend when e_font_icon_svg is on
echo '<i class="fas fa-star"></i>';

// RIGHT — routes through the manager, SVG or font as appropriate
\Elementor\Icons_Manager::render_icon( $settings['star_icon'], [ 'aria-hidden' => 'true' ] );

// WRONG — CSS assumes the inner container always exists
// .my-addon .elementor-widget-button .elementor-widget-container { gap: 8px; }
//   → no match when Optimized Markup drops the wrapper on the core Button widget

// RIGHT — target the widget/element wrapper or the content node
// .my-addon .elementor-widget-button .elementor-button { gap: 8px; }

// WRONG — JS that expects the wrapper on a core widget
// const c = widgetEl.querySelector('.elementor-widget-container'); c.dataset.x = 1; // c is null

// RIGHT — guard / target a stable node
// const c = widgetEl.querySelector('.elementor-widget-container') || widgetEl;

// WRONG — assuming your custom widget lost its wrapper (it didn't; base returns true)
// ...adding a second wrapper "to be safe" → double nesting

// RIGHT — override only if you WANT the reduction, mirroring core
public function has_widget_inner_wrapper(): bool {
    return ! \Elementor\Plugin::$instance->experiments->is_feature_active( 'e_optimized_markup' );
}

Cross-references

• Run elementor-dynamic-tag-register / elementor-dynamic-tag-fields when the work is registering a dynamic tag; if the tag outputs an icon, the Inline Font Icons rule here applies.
• Run elementor-dynamic-tag-ajax-select for large-dataset controls (unrelated to markup, but same addon surface).
• Run elementor-deprecations when a markup/API change you rely on may be deprecated — the has_widget_inner_wrapper / Icons_Manager APIs are current, but audit before bumping Elementor majors.

What this skill does NOT cover

• Atomic Widgets / Editor V4 (e_atomic_elements, Pro AtomicWidgetsModule::EXPERIMENT_NAME, e_pro_atomic_form, collection-loop) — a much larger architectural shift (new widget base, styles engine, schema) that deserves its own skill. This skill is only the two STABLE markup-changing performance experiments plus the experiments mechanics.
• Flexbox/Grid Container (container) beyond noting it's still an experiment — layout authoring, not addon-markup contract.
• The editor-JS side of experiments (React panels, elementorCommon.config.experimentalFeatures).
• Elementor's own internal widget CSS — you adapt to it, you don't edit it.

References

• Experiments manager + is_feature_active: core/experiments/manager.php:257; registered features manager.php:311-391; extension action elementor/experiments/default-features-registered manager.php:433; add_feature allowed keys manager.php:1049.
• has_widget_inner_wrapper() default true: includes/base/element-base.php:1588; wrapper print + script group: includes/base/widget-base.php:201,427.
• Core override example: includes/widgets/button.php:85; Pro override example: elementor-pro/modules/forms/widgets/form.php:45.
• Icons manager: inline-SVG gate includes/managers/icons.php:186,258; render_icon icons.php:354; get_icon_html icons.php:67; render_font_icon (SVG vs <i>) icons.php:309; enqueue_shim icons.php:206.
• Official documentation: https://developers.elementor.com/docs/
• Official documentation: https://go.elementor.com/wp-dash-inline-font-awesome/
• Official documentation: https://go.elementor.com/wp-dash-flex-container/