{"json_modified": "2016-03-28T08:48:38.816397", "uuid": "30c77bd9-8741-48ee-92cb-05bbca9b9631", "title": "Headers.keys()", "url": "/en-US/docs/Web/API/Headers/keys", "tags": ["API", "Reference", "Fetch API", "Headers", "Experimental", "Method"], "translations": [], "modified": "2015-12-02T05:39:19", "label": "Headers.keys()", "localization_tags": [], "locale": "en-US", "id": 168295, "last_edit": "2015-12-02T05:39:16", "summary": "The <code><strong>Headers.keys()</strong></code> method returns an <a href=\"/en-US/docs/Web/JavaScript/Reference/Iteration_protocols\" title=\"One addition of ECMAScript 2015 (ES6) is not new syntax or a new built-in, but a protocol. This protocol can be implemented by any object respecting some conventions.\"><code>iterator</code></a> allowing to go through all keys contained in this object. The keys are <a href=\"/en-US/docs/Web/API/ByteString\" title=\"ByteString is a UTF-8 String that corresponds to the set of all possible sequences of bytes. ByteString maps to a String when returned in JavaScript; generally, it's&#xA0;only used when interfacing with protocols that use bytes and strings interchangably, such as HTTP.\"><code>ByteString</code></a> objects.", "sections": [{"id": "Quick_Links", "title": null}, {"id": "Syntax", "title": "Syntax"}, {"id": "Return_value", "title": "Return value"}, {"id": "Example", "title": "Example"}, {"id": "Specifications", "title": "Specifications"}, {"id": "Browser_compatibility", "title": "Browser compatibility"}, {"id": "See_also", "title": "See also"}], "slug": "Web/API/Headers/keys", "review_tags": []}