How to get a synchronous function from an asynchronous function?

Question

Google

in the plugin I need to get data from localstorage

function getAccessKeyId() {
    var a;
    chrome.storage.local.get(null, function (result) {
        a = result.AWSAccessKeyId

    })
    console.log(a)
    return AWS_ACCESS_KEY;
}

gives undefined in console

Answer 1

If it is possible to use ES7, then you can use async / await, if not, you can use promises

function getAccessKeyId() {
    return new Promise(function(resolve){
        chrome.storage.local.get(null, function (result) {
            resolve(result.AWSAccessKeyId);
        });
    });
};

getAccessKeyId().then(function(key){
    console.log(key);
});