How to use function argument as part of variable?

Question

This works

chrome.storage.local.get(\'sizePref\', function(items) { // Get size preferences from storage
  var sizePref2 = items.sizePref.tops; // Set size to a          


        

Answer 1

When the property name is in a variable, you use the bracket syntax. So, instead of this:

items.sizePref.itemSize

you use this:

items.sizePref[itemSize]

---

In addition, you cannot return a value synchronously from an async callback. That logic is just wrong. So, you can't make a function getSize() that will return the result. The result will not be available until some time LATER after getSize() already returns. You would have to either pass a callback into getSize() or have getSize() return a promise.

function getSize(itemSize) {
  return new Promise(function(resolve) {
      chrome.storage.local.get('sizePref', function(items) { // Get size preferences from storage
        resolve(items.sizePref[itemSize]);
  });
}

getSize("whatever").then(function(result) {
    // code that uses the result here
});

Answer 2

If you are not familiar with promises (viz. unlikely) then you can use callbacks too. I personally think promises are a better way to solve your issue.

function getSize(itemSize, callback) {
  chrome.storage.local.get('sizePref', function(items) { 
    // Get size preferences from storage
    var sizePref = items.sizePref[itemSize]; //thanks @jfriend00
    callback (sizePref); //thanks at @Kevin Friedheim
  });
}
var mySize = getSize(tops, function (mySize) {
    console.log("This size that u are looking for is " + mySize)
});