Function: wpdai_get_experiment_variant

Return the current visitor’s variant key for an experiment, or null if they are unassigned or in holdout.

Description

Use this when you need the key itself (for logging, CSS classes, or switching among more than two Pro arms) instead of a yes/no check. It reads the assignment already applied on the request.

Location

File: includes/experiments/wpd-experiment-functions.php

Line: ~51

Function Signature

wpdai_get_experiment_variant( string $experiment_slug ): string|null

Parameters

Parameter	Type	Required	Description
$experiment_slug	string	Yes	A/B test slug from the A/B Test editor.

Return Value

Type: string|null

Description: Variant key such as control or treatment, or null when the visitor is not in that experiment (including holdout).

Example Usage

$variant = function_exists( 'wpdai_get_experiment_variant' )
    ? wpdai_get_experiment_variant( 'pricing-headline' )
    : null;

if ( 'treatment' === $variant ) {
    add_filter( 'the_title', 'my_treatment_title' );
}

if ( $variant ) {
    echo 'class="exp-pricing-' . esc_attr( $variant ) . '"';
}

Notes

Call on or after wp.
Holdout is null, not a variant key. Do not treat null as control unless that is an explicit product decision.
For a simple two-arm check, wpdai_in_experiment() is clearer.