ImmutableJS - 从Map中删除元素

Question

I have a map with this structure:

{
1: {},
2: {}
}

And I'd like to delete 2: {} from it (of course - return new collection without this). How can I do it? I tried this, but something is wrong:

 theFormerMap.deleteIn([],2) //[] should mean that it's right in the root of the map, and 2 is the name of the object I want to get rid of

Answer 1

只需在双引号中使用delete方法和属性：

theFormerMap = theFormerMap.delete("2")

Answer 2

Just use the delete method and pass the property you want to delete:

theFormerMap = theFormerMap.delete(2)

If this does not work then you have probably created theFormerMap using fromJS :

Immutable.fromJS({1: {}, 2: {}}).delete(2)
=> Map { "1": Map {}, "2": Map {} }

Key 2 is not removed as it is, in fact, a string key. The reason is that javascript objects convert numeric keys to strings.

However Immutable.js does support maps with integer keys if you construct them without using fromJS :

Immutable.Map().set(1, Immutable.Map()).set(2, Immutable.Map()).delete(2)
=> Map { 1: Map {} }

Answer 3

If you use immutable-data :

var immutableData = require("immutable-data")
var oldObj = {
  1: {},
  2: {}
}
var data = immutableData(oldObj) 
var immutableObj = data.pick()

//modify immutableObj by ordinary javascript method
delete immutableObj[2]

var newObj = immutableObj.valueOf()

console.log(newObj)                  // { '1': {} }
console.log(newObj===oldObj)         // [ { a: '2', b: '2' } ]
console.log(newObj[1]===oldObj[1])   // true