TypeScript error: Type ‘void’ is not assignable to type ‘boolean’

by

It means that the callback function you passed to this.dataStore.data.find should return a boolean and have 3 parameters, two of which can be optional:

  • value: Conversations
  • index: number
  • obj: Conversation[]

However, your callback function does not return anything (returns void). You should pass a callback function with the correct return value:

this.dataStore.data.find((element, index, obj) => {
    // ...

    return true; // or false
});

or:

this.dataStore.data.find(element => {
    // ...

    return true; // or false
});

Reason why it’s this way: the function you pass to the find method is called a predicate. The predicate here defines a boolean outcome based on conditions defined in the function itself, so that the find method can determine which value to find.

In practice, this means that the predicate is called for each item in data, and the first item in data for which your predicate returns true is the value returned by find.

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