Allow Cross-domain requests

Allow Cross-domain requests.php

<?php
add_filter( 'wp_headers', array( 'eg_send_cors_headers' ), 11, 1 );
function eg_send_cors_headers( $headers ) {

        $headers['Access-Control-Allow-Origin']      = get_http_origin(); // Can't use wildcard origin for credentials requests, instead set it to the requesting origin
        $headers['Access-Control-Allow-Credentials'] = 'true';

        // Access-Control headers are received during OPTIONS requests
        if ( 'OPTIONS' == $_SERVER['REQUEST_METHOD'] ) {

            if ( isset( $_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD'] ) ) {
                $headers['Access-Control-Allow-Methods'] = 'GET, POST, OPTIONS';
            }

            if ( isset( $_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS'] ) ) {
                $headers['Access-Control-Allow-Headers'] = $_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS'];
            }

        }

    return $headers;
}

add_action( 'init', 'handle_preflight' );

function handle_preflight() {
header("Access-Control-Allow-Origin: " . get_http_origin());
header("Access-Control-Allow-Methods: POST, GET, OPTIONS, PUT, DELETE");
header("Access-Control-Allow-Credentials: true");

if ( 'OPTIONS' == $_SERVER['REQUEST_METHOD'] ) {
    status_header(200);
    exit();
}

}

Info Here => WP-API/WP-API#144