Career
Turn- und Sportverein 1860 München
Janker started out in 1860 München"s youth system. He played for the reserve team in the 2004-2005 season, making 33 appearances, and in the 2005-2006 season, making 28 appearances. He eventually made his debut in the 2.
He would make three more appearance for the first team during the 2005-2006 season.
During the following season, he made three appearances for the reserve team before joining 1899 Hoffenheim. 1899 Hoffenheim
In his debut season with the club, he scored two goals in 31 league appearances.
His first appearance was a 1–1 draw on 19 August 2006 against SV Elversberg. His playing time was reduced the following season.
He appeared in 20 matches and two German Cup matches.
In 2009, Janker and his team member Andreas Ibertsberger came under investigation after failing to report to a doping control promptly after the match against Borussia Mönchengladbach on 2 February 2009. The German Football Association (DFB) suspended the investigation due to the lack of evidence, also Janker was later tested negative. The investigation was widely covered by the German press
On 23 May 2009 after the Bundesliga final, he announced his departure at the end of the season on 30 June 2009.
In his final season with the club, he made 17 league appearances. Hertha Bachelor of Science
On 28 May 2009, Janker signed a three-year contract with Hertha Bachelor of Science. In Berlin, Janker struggled to establish himself, sitting on the bench more often than not in his first season for Hertha.
He made 15 league appearances, one German Cup appearance, and eight Europa League appearances. He also made two appearances for the reserve team
At the end of the 2009-2010 season, Hertha were relegated to the 2.
Bundesliga. In the second division, Janker fared even worse. He made only one start, and came on off the bench a further three times in the league.
He also made seven appearances for the reserve team
Back in the Bundesliga for 2011-2012 season, Janker made 18 league appearances, three German Cup appearances, and two relegation playoff appearances. He made 21 appearances in all competitions for both first and second teams during the 2012-2013, 2013-2014, and 2014-2015 seasons. He left the club for Football Club Augsburg in January 2015.
Football Club Augsburg
During his debut season, he made two league appearances for Augsburg.
He was sent–off in the match. He is yet to debut during the 2015-2016 season.