Issue 6514 - IOToggle Custom Element

js/io-toggle.js

Index: js/io-toggle.js
===================================================================
new file mode 100644
--- /dev/null
+++ b/js/io-toggle.js
@@ -0,0 +1,85 @@
+/* globals module, require */
+
+"use strict";
+
+const IOElement = require("./io-element");
+
+class IOToggle extends IOElement
+{
+  // action, checked, and disabled should be reflected down the button
+  static get observedAttributes()
+  {
+    return ["action", "checked", "disabled"];
+  }
+
+  created()
+  {
+    this.addEventListener("click", this);
+    this.render();
+  }
+
+  get checked()
+  {
+    return this.hasAttribute("checked");
+  }
+
+  set checked(value)
+  {
+    booleanAttribute.call(this, "checked", value);
+    this.render();
+  }
+
+  get disabled()
+  {
+    return this.hasAttribute("disabled");
+  }
+
+  set disabled(value)
+  {
+    booleanAttribute.call(this, "disabled", value);
+    this.firstElementChild.disabled = this._disabled;
+  }
+
+  onclick(event)
+  {
+    if (!this.disabled)
+    {
+      this.checked = !this.checked;
+      this.dispatchEvent(new CustomEvent("change", {
+        bubbles: true,
+        cancelable: true,
+        detail: this.checked
+      }));
+    }
+  }
+
+  render()
+  {
+    this.html`
+    <button
+      role="checkbox"
+      data-action="${this.action}"
+      aria-checked="${this.checked}"
+      aria-disabled="${this.disabled}"
+    />`;
+  }
+}
+
+IOToggle.define("io-toggle");
+
+function asBoolean(value)
+{
+  return typeof value === "string" ? JSON.parse(value) : !!value;
+}
+
+function booleanAttribute(name, value)
+{
+  if (asBoolean(value))
+  {
+    this.setAttribute(name, "true");
+  }
+  else
+  {
+    this.removeAttribute(name);
+  }
+}