where when should i fetch for data code example

Example 1: How to Use the JavaScript Fetch API to Get Data

fetch('http://api.steampowered.com/ISteamUserStats/GetGlobalAchievementPercentagesForApp/v0002/?gameid=221380')
    .then(function(response) {
        return response.json();
    })
    .then(function(myJson) {
        console.log(JSON.stringify(myJson));
    });

Example 2: javascript how to fetch data

.catch(function() {

});