Javascript: How can I transform an array?

Question

I have this on a javascript var: (it's a http returned data, and I don't know if it's an array or string - (how can we see that?) - Update: using typeof returned "string", so it's a string.

[{"nomeDominio":"gggg.fa"},{"nomeDominio":"rarar.fa"}]

How can we pass/transform that, into something like this:

["gggg.fa","rarar.fa"]

?

Thanks a lot, MEM

Answer 1

You can figure out if is a string or an already parsed object by checking the type of your variable, e.g.:

ajax('url', function (response) {
  alert(typeof response);
});

You will now figure out if it's a "string" or an Array "object".

If it's a string, you can use the JSON.parse method as @alcuadrado suggest, otherwise you can simply use the array.

Several answers suggest the use of the for-in statement to iterate over the array elements, I would discourage you to use it for that.

The for-in statement should be used to enumerate over object properties, to iterate over Arrays or Array-like objects, use a sequential loop as @Ken Redler suggests.

You should really avoid for-in for this purpose because:

• The order of enumeration is not guaranteed, properties may not be visited in the numeric order.
• Enumerates also inherited properties.

You can also use the Array.prototype.map method to meet your requirements:

var response = [{"nomeDominio":"gggg.fa"},{"nomeDominio":"rarar.fa"}];
var array = response.map(function (item) { return item.nomeDominio; });
// ["gggg.fa", "rarar.fa"]