function maxSequence(array,step){
var _array = array.slice(), //clone array
_step = 1,
_arrayTemp = [],
i = 0;

var parseLogic = {
//result container
parseResults: [],
//set value to array,what's the last array of parseResults
set: function(n){
this.parseResults[this.parseResults.length-1].push(n);
},
//get the last array from parseResults
get: function(){
return this.parseResults[this.parseResults.length-1];
},
//put a new array in parseResults
addItem: function(){
this.parseResults.push([]);
},
//sort parseResults
sortByAsc: function(){
this.parseResults.sort(function(a,b){
return a.length - b.length;
});
}
};

//check params
_step = step || _step;

//sort array by asc
_array.sort(function(a,b){
return a - b;
});

//remove repeat of data
for(i = 0;i<_array.length;i++){
if(_array[i] != _array[i+1]){
_arrayTemp.push(_array[i]);
}
}
_array = _arrayTemp.slice();
_arrayTemp = [];

//parse array
parseLogic.addItem();
for(i = 0;i<_array.length;i++){
if(_array[i]+_step == _array[i+1]){
parseLogic.set(_array[i]);
continue;
}
if(_array[i]-_step == _array[i-1]){
parseLogic.set(_array[i]);
parseLogic.addItem();
}
}

//sort result
parseLogic.sortByAsc();

//get the max sequence
return parseLogic.get();

}

maxSequence([5,7,2,4,0,3,9],1); //return [2,3,4,5]
maxSequence([5,7,2,4,0,3,9],2); //return [5,7,9]