up

2-ui/2-events/01-introduction-browser-events/03-which-handlers-run/solution.md

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+The answer: `1` and `2`.
+
+The first handler triggers, because it's not removed by `removeEventListener`. To remove the handler we need to pass exactly the function that was assigned. And in the code a new function is passed, that looks the same, but is still another function.
+
+To remove a function object, we need to store a reference to it, like this:
+
+```js
+function handler() {
+  alert(1);
+}
+
+button.addEventListener("click", handler);
+button.removeEventListener("click", handler);
+```
+
+The handler `button.onclick` works independantly and in addition to `addEventListener`.

2-ui/2-events/01-introduction-browser-events/03-which-handlers-run/task.md

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+importance: 5
+
+---
+
+# Which handlers run?
+
+There's a button in the variable. There are no handlers on it.
+
+Which handlers run on click after the following code? Which alerts show up?
+
+```js no-beautify
+button.addEventListener("click", () => alert("1"));
+
+button.removeEventListener("click", () => alert("1"));
+
+button.onclick = () => alert(2);
+```