manage.get.gov/src/registrar/assets/js/get-gov-admin.js

/**
 * @file get-gov-admin.js includes custom code for the .gov registrar admin portal.
 *
 * Constants and helper functions are at the top.
 * Event handlers are in the middle.
 * Initialization (run-on-load) stuff goes at the bottom.
 */

// <<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>>
// Helper functions.
/** Either sets attribute target="_blank" to a given element, or removes it */
function openInNewTab(el, removeAttribute = false){
    if(removeAttribute){
        el.setAttribute("target", "_blank");
    }else{
        el.removeAttribute("target", "_blank");
    }
};

// <<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>>
// Event handlers.

// <<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>><<>>
// Initialization code.

/** An IIFE for pages in DjangoAdmin which may need custom JS implementation.
 * Currently only appends target="_blank" to the domain_form object,
 * but this can be expanded.
*/
(function (){
    /*
    On mouseover, appends target="_blank" on domain_form under the Domain page.
    The reason for this is that the template has a form that contains multiple buttons.
    The structure of that template complicates seperating those buttons 
    out of the form (while maintaining the same position on the page).
    However, if we want to open one of those submit actions to a new tab - 
    such as the manage domain button - we need to dynamically append target.
    As there is no built-in django method which handles this, we do it here. 
    */
    function prepareDjangoAdmin() {
        let domainFormElement = document.getElementById("domain_form");
        let domainSubmitButton = document.getElementById("manageDomainSubmitButton");
        if(domainSubmitButton && domainFormElement){
          domainSubmitButton.addEventListener("mouseover", () => openInNewTab(domainFormElement, true));
          domainSubmitButton.addEventListener("mouseout", () => openInNewTab(domainFormElement, false));
        }
    }

    prepareDjangoAdmin();
})();