AJAX wrapper for native JavaScript and WordPress REST API

wp-rest-api-wrapper.js

/**
* AJAX обертка для WordPress REST API
*/

let sb_ajax = function ( ep, success, error, type = 'GET', data = '' ) {

    url = wpApiSettings.root + ep;
    // Feature detection
    if ( !window.XMLHttpRequest ) return;

    // Create new request
    var request = new XMLHttpRequest();

    // Setup callbacks
    request.onreadystatechange = function () {

      // If the request is complete
      if ( request.readyState === 4 ) {

        // If the request failed
        if ( request.status !== 200 ) {
          if ( error && typeof error === 'function' ) {
            error( request.responseText, request );
          }
          return;
        }

        // If the request succeeded
        if ( success && typeof success === 'function' ) {
          success( request.responseText, request );
        }
      }

    };

    // Get the HTML
    request.open( type, url );

    if(type != 'GET'){
      request.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
    }

    request.setRequestHeader("X-WP-Nonce", wpApiSettings.nonce);

    if(data){
      request.send(JSON.stringify(data));
    } else {
      request.send();
    }

};