{"json_modified": "2016-09-18T19:36:39.176643", "uuid": "40b06413-4a29-42ab-ba67-e921cec26869", "title": "webRequest.onBeforeSendHeaders", "url": "/en-US/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeSendHeaders", "tags": ["API", "Non-Standard", "webRequest", "Reference", "Event", "Non-standard", "Extensions", "Add-ons", "WebExtensions", "onBeforeSendHeaders", "add-ons"], "translations": [], "modified": "2016-09-18T19:36:39", "label": "webRequest.onBeforeSendHeaders", "localization_tags": [], "locale": "en-US", "id": 172309, "last_edit": "2016-09-18T18:57:27", "summary": "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.", "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"}, {"id": "Example_add-ons", "title": "Example add-ons"}], "slug": "Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeSendHeaders", "review_tags": []}