works

1-js/4-data-structures/4-object/5-count-properties/_js.view/solution.js

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+function count(obj) { 
+  return Object.keys(obj).length;
+}
+

1-js/4-data-structures/4-object/5-count-properties/_js.view/test.js

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+describe("count", function() {
+  it("counts the number of properties", function() {
+    assert.equal( count({a: 1, b: 2}), 2 );
+  });
+
+  it("returns 0 for an empty object", function() {
+    assert.equal( count({}), 0 );
+  });
+
+  it("ignores symbolic properties", function() {
+    assert.equal( count({ [Symbol('id')]: 1 }), 0 );
+  });
+});

1-js/4-data-structures/4-object/5-count-properties/task.md

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+importance: 5
+
+---
+
+# Count properties
+
+Write a function `count(obj)` that returns the number of properties in the object:
+
+```js
+let user = {
+  name: 'John',
+  age: 30
+};
+
+alert( count(user) ); // 2
+```
+
+Try to make the code as short as possible.
+
+P.S. Ignore symbolic properties, count only "regular" ones.
+