Parsing json responses the lazy (as in I-hate-if's) way

(Yes, I don't know how to name the tip).

Suppose you have an API call that might answer a json/js object in the following formats:

One item:

{
  foos: {
    bar: 1
  }
}

A bunch of items:

{
  foos: [{
    bar: 1
  }, {
    bar: 6
  }]
}

No item at all:

{
  foos: { }
}

BTW: This is actually quite common in API's that just translate XML to JSON.

One way to handle all 3 cases is to simply do:

var array_of_foos = [].concat(obj.foos || []);

This way array_of_foos will always contain either an empty array, or an array with all the items.