Various improvements

js/input/common/IFocus.js

@@ -0,0 +1,40 @@
+import IInput from "../IInput"
+
+export default class IFocus extends IInput {
+
+    /** @type {(e: FocusEvent) => void} */
+    #focusHandler
+
+    /** @type {(e: FocusEvent) => void} */
+    #focusoutHandler
+
+    constructor(target, blueprint, options = {}) {
+        options.listenOnFocus ??= true
+        super(target, blueprint, options)
+        const self = this
+        this.#focusHandler = e => {
+            e.preventDefault()
+            this.focused()
+        }
+        this.#focusoutHandler = e => {
+            e.preventDefault()
+            this.unfocused()
+        }
+    }
+
+    listenEvents() {
+        this.target.addEventListener("focus", this.#focusHandler)
+        this.target.addEventListener("focusout", this.#focusoutHandler)
+    }
+
+    unlistenEvents() {
+        this.target.removeEventListener("focus", this.#focusHandler)
+        this.target.removeEventListener("focusout", this.#focusoutHandler)
+    }
+
+    focused() {
+    }
+
+    unfocused() {
+    }
+}