execute njs script before proxy_pass

Question

I am configuring à nginx location but I need to run a script that update requestBody before redirection :

This my conf but when i deploy it still redirect without update requestBody or return error

Parent nginx.conf:

     // .....
     js_import checkScript from  /etc/nginx/js/scripts/checkScript.js;
     // ....

In checkScript.js :

export default {
    rights
}

function rights(r) {
    const body = JSON.parse(r.requestBody);
    if (body.isAdmin) {
        body.rights = ['ADMIN'];
        r.requestBody = JSON.stringify(body);
    } else {
        r.return(403, 'Not admin');
    }
}

products.http-service.conf :

location /api/data/products/new {
    set $gateway_role "dev.yumStore";
    set $gateway_realm "yumStore";

    auth_request /_tokenExchange;

    # check rights and update body
    js_content checkScript.rights;

    proxy_set_header "Authorization" $gateway_auth_header;

    # redirection
    proxy_pass $OUTGATEWAY/api/data/products/new;
}

Thanks for help!!