&#39;Set 类型的错误参数<string> &#39; 不能分配给类型为 &#39;string&#39; 的参数

Question

I have two property :

  roleIdFormIdMap: Map<string, Set<string>>;
  appIdFormIdMap: Map<string, Set<string>>;

I have set the value on both property.

Now i need to retrieve the value :

let formIds = this.props.roleIdFormIdMap.get(securityRoleId);

const everyoneFormIds = this.props.roleIdFormIdMap.get(everyoneSecurityRole);
if (formIds && everyoneFormIds) {
 ///how to add value , here I am getting the error Argument of type 'Set<string>' is not assignable 
  to parameter of type 'string'.ts(2345)
  formIds.add(everyoneFormIds);
}

if (appId && appId !== this.appNoSelectionKey && formIds) {
  const formIdsBasedOnApp = this.props.appIdFormIdMap.get(appId);
  //same thing here , how to acheive it
  formIds = _.intersectionWith(formIdsBasedOnApp, formIds, _.isEqual);
}

Answer 1

I would do something like this to aggregate sets:

 const a = new Set([1,2,3]) const b = new Set([3,4,5]) // Aggregate results from a to b a.forEach((v) => b.add(v)) console.log([...b])

To my understanding the method Set.add only admits one argument and denies iterators Set javascript

Answer 2

• formIds type here is Set<string> | undefined Set<string> | undefined , so you will not be directly able to call .add on it
• you can call it this way: formIds?.add(???)
• now add function on Set takes string , so you wont be able to pass everyoneFormIds here because type of everyoneFormIds is Set<string> | undefined Set<string> | undefined

Try this:

everyoneFormIds.forEach((id) => formIds.add(id))