{"json_modified": "2016-09-18T19:37:20.947519", "uuid": "e7ace405-43f1-4951-92a5-079bbb9802db", "title": "webRequest.onSendHeaders", "url": "/en-US/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onSendHeaders", "tags": ["API", "webRequest", "onSendHeaders", "Reference", "Event", "Non-standard", "Extensions", "Add-ons", "WebExtensions", "Non-Standard", "add-ons"], "translations": [], "modified": "2016-09-18T19:37:21", "label": "webRequest.onSendHeaders", "localization_tags": [], "locale": "en-US", "id": 172327, "last_edit": "2016-09-18T19:01:45", "summary": "This event is fired just before sending headers. If your add-on or some other add-on modified headers in <code><a href=\"/en-US/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeSendHeaders\" title=\"This event is triggered before sending any HTTP data, but after all HTTP headers are available. This is a good place to listen if you want to modify HTTP request headers.\"><code>onBeforeSendHeaders</code></a></code>, you'll see the modified version here.", "sections": [{"id": "Quick_Links", "title": null}, {"id": "Syntax", "title": "Syntax"}, {"id": "addListener_syntax", "title": "addListener syntax"}, {"id": "Parameters", "title": "Parameters"}, {"id": "Additional_objects", "title": "Additional objects"}, {"id": "details", "title": "details"}, {"id": "Browser_compatibility", "title": "Browser compatibility"}, {"id": "Compatibility_notes", "title": "Compatibility notes"}, {"id": "Chrome", "title": "Chrome"}, {"id": "Firefox", "title": "Firefox"}, {"id": "Opera", "title": "Opera"}, {"id": "Examples", "title": "Examples"}], "slug": "Mozilla/Add-ons/WebExtensions/API/webRequest/onSendHeaders", "review_tags": []}