¿Por qué mi función no devuelve verdadero? vuelve indefinido

Aquí está mi código:

 const generateJson = () => { var url = "https://api.insee.fr/entreprises/sirene/V3/siret/32773318400516"; const xhr = new XMLHttpRequest(); xhr.open('GET', url); xhr.setRequestHeader("Accept", "application/json"); xhr.setRequestHeader("Authorization", "Bearer 54cb0781-a0ea-3d5b-9e81-f18ac252dfa4"); xhr.onreadystatechange = () => { if (xhr.readyState === XMLHttpRequest.DONE) { console.log(xhr.status); console.log(xhr.response); return true; } else { return false; } } xhr.send(); } console.log(typeof(generateJson()));

aquí hay una parte de mi salida:

 undefined 200 {"header":{"statut":200,"message":"ok"},"etablissement":{"siren":"327733184","nic":"00516","siret":"32773318400516","statutDiffusionEtablissement":"O","dateCreationEtablissement":"2009-06-26","trancheEffectifsEtablissement":"42","anneeEffectifsEtablissement":"2019","activitePrincipaleRegistreMetiersEtablissement":null,"dateDernierTraitementEtablissement":"2021-10-27T08:26:07","etablissementSiege":true,"nombrePeriodesEtablissement":2,"uniteLegale":{"etatAdministratifUniteLegale":"A","statutDiffusionUniteLegale":"O","dateCreationUniteLegale":"1983-04-01","categorieJuridiqueUniteLegale":"5710","denominationUniteLegale":"MICROSOFT FRANCE"

cual es la solucion por favor