Post data with api React-native

Question

this api niceyl work in postman but I try this code in react-native it is not working how to fix it?

const a ={
    ad:'test',
    telefon:'test',
    islem:'test',
    sube:'test',
    saat:'test',
};
async function harrik(){
   await fetch('https://localhost/api/test/cetran', {
    method: 'POST',
    headers: {
        'Accept':'application/json',
        'Content-Type': 'application/json',
    },
    body:a,
    }).then((response)=>{
        console.log(JSON.stringify(response));
    }).catch((e)=>{
        console.log(e);
    });
}

Answer 1

I solved like this:

body:JSON.stringify(a),