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Does a function pickup latest changes?

importance: 5

The function sayHi uses an external variable name. When the function runs, which value is it going to use?

let name = "John";

function sayHi() {
  alert("Hi, " + name);

name = "Pete";

sayHi(); // what will it show: "John" or "Pete"?

Such situations are common both in browser and server-side development. A function may be scheduled to execute later than it is created, for instance after a user action or a network request.

So, the question is: does it pick up the latest changes?

The answer is: Pete.

A function gets outer variables as they are now, it uses the most recent values.

Old variable values are not saved anywhere. When a function wants a variable, it takes the current value from its own Lexical Environment or the outer one.