is/was Javascript open source? what matters is the platform no one cared if Javascript the language was open source when it was the only way to do client side

is/was Javascript open source? what matters is the platform no one cared if Javascript the language was open source when it was the only way to do client side scripting for web pages. similarly Swift has iOS and OSX - other languages are available on these but I guess developers are anticipating Apple emphasising Swift over Objective-C going forward