I am having a problem with my code:

var arrays = [[1, 2, 3], [4, 5], [6]];

console.log(reduce(arrays,function(array,b){

  return array.push(b);

}));



function reduce(array,combine){

  var current = [];

  for(var i = 0;i<array.length;i += 1){

    current = combine(current,array[i]);

  }

  return current;

}

console.log(reduce([1, 2, 3, 4], function(array, b) {

  return array.push(b);

}));



// → [1, 2, 3, 4, 5, 6]

I get this error:

TypeError: array.push is not a function (line 3) 

As far as I understand, this is because it is treating the array argument as something other than an array. However, I thought I fed it the variable current which is an array. Can someone explain the problem? Thanks.