closure

Author: iliakan

1-js/06-advanced-functions/03-closure/1-closure-latest-changes/solution.md

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+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.

1-js/06-advanced-functions/03-closure/1-closure-latest-changes/task.md

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+importance: 5
+
+---
+
+# Does a function pickup latest changes?
+
+The function sayHi uses an external variable name. When the function runs, which value is it going to use?
+
+```js
+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?

1-js/06-advanced-functions/03-closure/8-make-army/_js.view/solution.js renamed to 1-js/06-advanced-functions/03-closure/10-make-army/_js.view/solution.js

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+The answer is: **Pete**.
+
+The `work()` function in the code below gets `name` from the place of its origin through the outer lexical environment reference:
+
+![](lexenv-nested-work.svg)
+
+So, the result is `"Pete"` here.
+
+But if there were no `let name` in `makeWorker()`, then the search would go outside and take the global variable as we can see from the chain above. In that case the result would be `"John"`.

1-js/06-advanced-functions/03-closure/8-make-army/_js.view/source.js renamed to 1-js/06-advanced-functions/03-closure/10-make-army/_js.view/source.js

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+importance: 5
+
+---
+
+# Which variables are available?
+
+The function `makeWorker` below makes another function and returns it. That new function can be called from somewhere else.
+
+Will it have access to the outer variables from its creation place, or the invocation place, or both?
+
+```js
+function makeWorker() {
+  let name = "Pete";
+
+  return function() {
+    alert(name);
+  };
+}
+
+let name = "John";
+
+// create a function
+let work = makeWorker();
+
+// call it
+work(); // what will it show?
+```
+
+Which value it will show? "Pete" or "John"?