Get json value on any php page

[TuffyA]

I am creating json object but can't access its value in php.I am trying to access json object in php and assign that object to php variable.My js code is\[code\]var arr= []; var data=http://stackoverflow.com/questions/15583973/{"tab" : 'system' };jObjArr = arr.push(data); var JSONstr = JSON.stringify(jObjArr);\[/code\]what i am missing ?I try to get tab value on that page in php.