javascript - Dart equivalent of Array.prototype.map()? - Stack Overflow

I try to get the id's from List of Maps in Dart. In JavaScript it would be something like this:

var list = [{id:3, name:'third'}, {id:4, name:'fourth'}];
var result = list.map(function(x){return x.id;});

This should give the result

[3, 4]

Is there a simple way of doing this in Dart?

---

So far I was able to do this (in Dart):

var list = [{'id':3, 'name':'third'},{'id':4, 'name':'fourth'}];
var result = list.map((x) => x['id']);

The result is a "MappedListIterable" (not sure what that is) and you cannot use result[0] like you can with a normal List. How can I make a list of this?

I try to get the id's from List of Maps in Dart. In JavaScript it would be something like this:

var list = [{id:3, name:'third'}, {id:4, name:'fourth'}];
var result = list.map(function(x){return x.id;});

This should give the result

[3, 4]

Is there a simple way of doing this in Dart?

---

So far I was able to do this (in Dart):

var list = [{'id':3, 'name':'third'},{'id':4, 'name':'fourth'}];
var result = list.map((x) => x['id']);

The result is a "MappedListIterable" (not sure what that is) and you cannot use result[0] like you can with a normal List. How can I make a list of this?

• javascript
• arrays
• dart

Share Improve this question Follow edited Apr 27, 2015 at 0:51 Hendrik Jan asked Apr 26, 2015 at 23:47 Hendrik JanHendrik Jan 4,90899 gold badges4747 silver badges7878 bronze badges 0

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1 Answer 1

Sorted by: Reset to default 8

See the API for List.map and the API for Iterable (which it returns). You can get the nth element from the iterable using .elementAt(n) or the first element using .first.

var list = [{'id':3, 'name':'third'},{'id':4, 'name':'fourth'}];
var result = list.map((x) => x['id']).first;

You can also turn it back into a List using .toList():

var resultList = list.map((x) => x['id']).toList();