Argument of type X is not assignable to parameter of type X

Question

Good day  I m new to Type Script  using VSCode   Getting following errors       error TS2322  Type        string  is not assignable to type  string       error TS2322  Type        number  is not assignable to type  number      The Code    DTO ts  interface DTO        getId    number      getValue    string    export   DTO    LinkedObject ts  class LinkedObject        public value  string    Not Set       public id  number   0       constructor value   string  id   number            this value   value          this id   id          export   LinkedObject    I am trying to instantiate LinkedObject class using above mentioned interface methods    TravelClientFormPopulator ts  class TravelClientFormPopulator        public populateComboBoxUsingDTOs dataObjects  Array lt DTO gt   comboBoxID  string   void               Get the combo box         var selectElement    lt HTMLSelectElement gt  document getElementById comboBoxID              Reset the options          selectElement options length   0           var linkedObjectsToAdd  LinkedObject     new Array lt LinkedObject gt              var defaultLinkedObject  LinkedObject   new LinkedObject  Not Selected   0            linkedObjectsToAdd push defaultLinkedObject            for  var i   0  i  lt  dataObjects length  i                  var value  string   dataObjects i  getValue     Error here             var id  number   dataObjects i  getId     And here             var linkedObject  LinkedObject   new LinkedObject value  id                       Any help will be highly appreciated

User · Answer

In my case  it was that I had a custom interface called Item  but I imported accidentally because of the auto-completion  the angular Item class  Be sure that you re importing from the right package

User · Answer

I was getting this one on this case       then  error  any  response  any    gt       console info  document error     error     console info  documenr response     response     return new MyModel             on this case making parameters optional would make ts stop complaining   then  error   any  response   any    gt

User · Answer

you just use variable type any and remove these types of problem   error code       let accessToken   res    localStorage setItem LocalStorageConstants TOKEN KEY  accessToken     given error Argument of type      is not assignable to parameter of type  string    success Code       var accessToken any   res    localStorage setItem LocalStorageConstants TOKEN KEY  accessToken     we create var type variable then use variable type any and resolve this issue   any   handle any type of value so that remove error

User · Answer

This problem basically comes when your compiler gets failed to understand the difference between cast operator of the type string to Number   you can use the Number object and pass your value to get the appropriate results for it by using Number  lt  lt  lt  lt    Variable Name

User · Answer

Also adding other Scenarios where you may see these Errors        First Check you compiler version  Download latest Typescript compiler   to support ES6 syntaxes   typescript still produces output even with typing errors this doesn t   actually block development       When you see these errors Check for Syntaxes in initialization or when Calling these methods or variables  Check whether the parameters of the functions are of wrong data Type you initialized as  string  and assigning a  boolean  or  number   For Example  1    private errors  string        somewhere in code you assign a boolean value to  string  errors      this errors true     or      this error 5   2    private values  Array lt number gt           this values push value      Argument of type  X  is not assignable to parameter of type  X    The Error message here is because the Square brackets for Array Initialization is missing  It works even without it  but VS Code red alerts   private values  Array lt number gt            this values push value     Note  Remember that Javascript typecasts according to the value assigned  So typescript notifies them but the code executes even with these errors highlighted in VS Code  Ex     var a 2   typeof a      number   var a  Ignatius    typeof a      string

User · Answer

For what it worth  if anyone has this problem only in VSCode  just restart VSCode and it should fix it  Sometimes  Intellisense seems to mess up with imports or types    Related to Typescript  Argument of type   39 RegExpMatchArray  39  is not assignable to parameter of type   39 string  39

User · Answer

I m doing angular 2 and typescript and I didn t realize I had a space in my arrow notation  I had  map key    gt  instead of  map key   gt    Definitely keep your eyes open for stupid syntax errors

User · Answer

You miss parenthesis   var value  string   dataObjects i  getValue     var id  number   dataObjects i  getId

User · Answer

In my case  strangely enough  I was missing the import of the class it was complaining about and my IDE didn t detect it

[typescript] Argument of type 'X' is not assignable to parameter of type 'X'

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