Not updating value inside Map

[NareshNaredla]

Hai all,

Iam having a map like : var map = Immutable.Map({a:1, b:{d:2}, c:3});

now i want to update value of 'd'...and i tried the following :

1. map.set(['b','d']),1000)
   2.map = map.updateIn(['b', 'd'], function(value) { return 1000; });// i know it is for nested map...

and not able to update ...so could you please suggest me how to update that value

[NareshNaredla]

and tried like this also : map.set(['b','d'], function(value) { return 1000; })

[leebyron]

Since that value is a mutable object, not an immutable map, the immutable API does not apply to it (see Object's API). If your update backs up one level, then it points to the object instead of the key within the object:

var map1 = Immutable.Map({a:1, b:{d:2}, c:3});
var map2 = map1.update('b', function (value) { value.d = 1000; return value; })

However, note that this has mutated a mutable value, which your original map still points to, so in this case map2 === map1.

You could also return a copy of this object:

var map1 = Immutable.Map({a:1, b:{d:2}, c:3});
var map2 = map1.update('b', function (value) { 
  var newValue = {};
  for (var k in value) {
    if (value.hasOwnProperty(k)) {
      newValue[k] = value[k];
    }
  }
  newValue.d = 1000; 
  return newValue; 
})

And now map2 !== map1 and map1's mutable object has not been changed. However this highlights one of the use cases of Immutable Map. If you desired the second behavior, then using an immutable Map instead of a mutable Object as a nested value would provide an API much easier to work with:

var map1 = Immutable.Map({a:1, b:Immutable.Map({d:2}), c:3});
var map2 = map1.update('b', function (value) { return value.set('d', 1000); })