flow like the river

VISUALIZACION/node_modules/graphql/polyfills/arrayFrom.js.flow

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+// @flow strict
+import { SYMBOL_ITERATOR } from './symbols';
+
+declare function arrayFrom<T>(arrayLike: Iterable<T>): Array<T>;
+// eslint-disable-next-line no-redeclare
+declare function arrayFrom<T: mixed>(
+  arrayLike: mixed,
+  mapFn?: (elem: mixed, index: number) => T,
+  thisArg?: mixed,
+): Array<T>;
+
+/* eslint-disable no-redeclare */
+// $FlowFixMe[name-already-bound]
+const arrayFrom =
+  Array.from ||
+  function (obj, mapFn, thisArg) {
+    if (obj == null) {
+      throw new TypeError(
+        'Array.from requires an array-like object - not null or undefined',
+      );
+    }
+
+    // Is Iterable?
+    const iteratorMethod = obj[SYMBOL_ITERATOR];
+    if (typeof iteratorMethod === 'function') {
+      const iterator = iteratorMethod.call(obj);
+      const result = [];
+      let step;
+
+      for (let i = 0; !(step = iterator.next()).done; ++i) {
+        result.push(mapFn.call(thisArg, step.value, i));
+        // Infinite Iterators could cause forEach to run forever.
+        // After a very large number of iterations, produce an error.
+        // istanbul ignore if (Too big to actually test)
+        if (i > 9999999) {
+          throw new TypeError('Near-infinite iteration.');
+        }
+      }
+      return result;
+    }
+
+    // Is Array like?
+    const length = obj.length;
+    if (typeof length === 'number' && length >= 0 && length % 1 === 0) {
+      const result = [];
+
+      for (let i = 0; i < length; ++i) {
+        if (Object.prototype.hasOwnProperty.call(obj, i)) {
+          result.push(mapFn.call(thisArg, obj[i], i));
+        }
+      }
+      return result;
+    }
+
+    return [];
+  };
+
+export default arrayFrom;