Assign value of fetch to a variable

Question

Using code

let data;

fetch(url)
    .then(result => result.json())
    .then(json => {data = json})

console.log(data)

data console logs as undefined, whereas

let data;
    
fetch(url)
    .then(result => result.json())
    .then(json => console.log(json))

logs the result as expected. How come? How can I store result of fetch in a variable for future use?