Jokl was born in Bzenec (then Bisenz), Southern Moravia (now the Czech Republic), to Heinrich, a merchant, and Emilie née Haas.

After Adolf Hitler came to power in Germany, Jokl's manuscripts started being rejected and he was no longer invited to conferences.

Later that year, Jokl submitted an application (supported by the Dean) to be equalized with "persons of mixed blood of 1st degree“ in order to have admittance to libraries.

Georg Solta, who went on to become a professor of Indo-European linguistics, would often visit him during the following four years, in order to further his studies and to maintain personal interaction with his mentor.

In one of his applications, he also asked for permission to take along his library, but was opposed by Dean Christian, who was very interested in keeping Jokl's extensive collection at the University.

Jokl's library also contained his life work and the handwritten supplements to the Albanian vocabulary by Gustav Meyer.

Jokl's life's work, an edition of the Etymological Dictionary of Albanian by Gustav Meyer, with handwritten addendas, is untraceable.

In 2012, Posta Shqiptare, the national postal service of Albania, honored Jokl with a postage stamp in a series commemorating foreign Albanologists, linguists who have studied the Albanian language.