Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/tools/js/CharacterSheet/containers/SpellSlotManager/SpellSlotManagerLevel/SpellSlotManagerLevel.tsx

@@ -0,0 +1,41 @@
+import React from "react";
+
+import { FormatUtils } from "@dndbeyond/character-rules-engine/es";
+
+import SlotManager from "../../../../Shared/components/SlotManager";
+
+interface Props {
+  level: number;
+  available: number;
+  used: number;
+  onSlotSet?: (level: number, used: number) => void;
+  isInteractive: boolean;
+}
+export default class SpellSlotManagerLevel extends React.PureComponent<Props> {
+  handleSlotSet = (used: number): void => {
+    const { onSlotSet, level } = this.props;
+
+    if (onSlotSet) {
+      onSlotSet(level, used);
+    }
+  };
+
+  render() {
+    let { level, available, used, isInteractive } = this.props;
+
+    return (
+      <div className="ct-spell-slot-manager__level">
+        <div className="ct-spell-slot-manager__level-name">
+          {FormatUtils.ordinalize(level)} Level
+        </div>
+        <SlotManager
+          available={available}
+          used={used}
+          onSet={this.handleSlotSet}
+          size="small"
+          isInteractive={isInteractive}
+        />
+      </div>
+    );
+  }
+}

ddb_main/tools/js/CharacterSheet/containers/SpellSlotManager/SpellSlotManagerLevel/index.ts

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+import SpellSlotManagerLevel from "./SpellSlotManagerLevel";
+
+export default SpellSlotManagerLevel;
+export { SpellSlotManagerLevel };