What is the ruling on saying "Allahu Akbar" (God is the Greatest) out of joy, and is what happened with "Allahu Akbar" being said through mosque loudspeakers after the announcement of election results permissible and does it have a Sharia basis?

Saying "Allahu Akbar" (Takbir) in times of joy and happiness is widespread in the Sunnah and well-known among the Salaf. Examples include the Companions' Takbir when they were given the good news that they would be half the inhabitants of Paradise, and the Prophet, peace be upon him, saying Takbir when he killed Abu Jahl, when he was given the good news of Umm Sulaym's birth, and upon his arrival in Medina. Similarly, Uthman, Ali, Ibn Abbas, Ibn Mas'ud, and Haram ibn Milhan, may Allah be pleased with them, said Takbir on various occasions, as did Ghudayf ibn al-Harith. There is no prophetic command specifying a particular formula or number for this Takbir. The matter is broad in this regard, and it is best to combine it with Alhamdulillah (praise be to Allah) to express gratitude for the blessing.