Property has no initializer and is not definitely assigned in the constructor

Question

in my Angular app i have a component   import   MakeService   from          services make service   import   Component  OnInit   from   angular core     Component     selector   app-vehicle-form     templateUrl     vehicle-form component html     styleUrls      vehicle-form component css      export class VehicleFormComponent implements OnInit     makes  any      vehicle          constructor private makeService  MakeService         ngOnInit         this makeService getMakes   subscribe makes   gt    this makes   makes       console log  MAKES   this makes                  onMakeChange        console log  VEHICLE   this vehicle           but in the  makes  property I have a mistake   I dont know what to do with it

User · Answer

You can also do the following if you really don t want to initialise it  makes   any

User · Answer

Get this error at the time of adding Node in my Angular project -  TSError    Unable to compile TypeScript   path  base api ts 19 13 - error TS2564  Property  apiRoot Path  has no initializer and is not definitely assigned in the constructor  private apiRootPath  string   Solution - Added  quot strictPropertyInitialization quot   false in  compilerOptions  of tsconfig json  my package json -  quot dependencies quot                  quot  angular common quot    quot  10 1 3 quot        quot  types express quot    quot  4 17 9 quot        quot express quot    quot  4 17 1 quot              Ref URL - https   www ryadel com en ts2564-ts-property-has-no-initializer-typescript-error-fix-visual-studio-2017-vs2017

User · Answer

Go to your tsconfig json file and change   quot noImplicitReturns quot   false then add  quot strictPropertyInitialization quot   false to your tsconfig json file under  quot compilerOptions quot  property  Here is what my tsconfig json file looks like tsconfig json            quot compilerOptions quot                           quot noImplicitReturns quot   false                        quot strictPropertyInitialization quot   false         quot angularCompilerOptions quot                           Hope this will help    Good Luck

User · Answer

I think you are using the latest version of TypeScript  Please see the section  Strict Class Initialization  in the link   There are two ways to fix this   A  If you are using VSCode you need to change the TS version that the editor use   B  Just initialize the array when you declare it inside the constructor   makes  any          constructor private makeService  MakeService           Initialization inside the constructor    this makes

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As of TypeScript 2 7 2  you are required to initialise a property in the constructor if it was not assigned to at the point of declaration   If you are coming from Vue  you can try the following    Add  strictPropertyInitialization   true to your tsconfig json If you are unhappy with disabling it you could also try this makes  any     undefined  Doing this requires that you access the properties with null check      operator i e  this makes  length You could as well try makes   any     this tells TS that the value will be assigned at runtime

User · Answer

If you want to initialize an object based on an interface you can initialize it empty with following statement  myObj  IMyObject      as IMyObject

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You either need to disable the --strictPropertyInitialization that Sajeetharan referred to  or do something like this to satisfy the initialization requirement  makes  any

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change the fieldname   any      to this  fieldname   any

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It is because TypeScript 2 7 includes a strict class checking where all the properties should be initialized in the constructor  A workaround is to add   the   as a postfix to the variable name   makes   any

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Just go to tsconfig json and set   strictPropertyInitialization   false   to get rid of the compilation error   Otherwise you need to initialize all your variables which is a little bit annoying

User · Answer

The error is legitimate and may prevent your app from crashing  You typed makes as an array but it can also be undefined  You have 2 options  instead of disabling the typescript s reason for existing      1  In your case the best is to type makes as possibily undefined  makes   any      or makes  any     undefined  In this case the compiler will inform you whenever you try to access to makes that it could be undefined  For exemple if the     lt -- Not ok lines below are executed before getMakes finished or if getMakes fails  your app will crash and a runetime error will be thrown  makes 0      lt -- Not ok makes map          lt -- Not ok  if  makes  makes 0      lt -- Ok makes   0      lt -- Ok  makes        map          lt -- Ok  2  You can assume that it will never fail and that you will never try to access it before initialization by writing the code below  risky    So the compiler won t take care about it  makes   any

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We may get the message Property has no initializer and is not definitely assigned in the constructor when adding some configuration in the tsconfig json file so as to have an Angular project compiled in strict mode    compilerOptions        strict   true     noImplicitAny   true     noImplicitThis   true     alwaysStrict   true     strictNullChecks   true     strictFunctionTypes   true     strictPropertyInitialization   true    Indeed the compiler then complains that a member variable is not defined before being used   For an example of a member variable that is not defined at compile time  a member variable having an  Input directive    Input   userId  string    We could silence the compiler by stating the variable may be optional    Input   userId   string    But then  we would have to deal with the case of the variable not being defined  and clutter the source code with some such statements   if  this userId      else       Instead  knowing the value of this member variable would be defined in time  that is  it would be defined before being used  we can tell the compiler not to worry about it not being defined   The way to tell this to the compiler is to add the   definite assignment assertion operator  as in    Input   userId   string    Now  the compiler understands that this variable  although not defined at compile time  shall be defined at run-time  and in time  before it is being used   It is now up to the application to ensure this variable is defined before being used   As an an added protection  we can assert the variable is being defined  before we use it   We can assert the variable is defined  that is  the required input binding was actually provided by the calling context   private assertInputsProvided    void     if   this userId        throw  new Error  The required input  userId  was not provided            public ngOnInit    void        Ensure the input bindings are actually provided at run-time   this assertInputsProvided        Knowing the variable was defined  the variable can now be used   ngOnChanges       this userService get this userId       subscribe user   gt          this update user confirmedEmail               Note that the ngOnInit method is called after the input bindings attempt  this  even if no actual input was provided to the bindings   Whereas the ngOnChanges method is called after the input bindings attempt  and only if there was actual input provided to the bindings

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Can t you just use a Definite Assignment Assertion   See https   www typescriptlang org docs handbook release-notes typescript-2-7 html definite-assignment-assertions   i e  declaring the property as makes   any    The   assures typescript that there definitely will be a value at runtime   Sorry I haven t tried this in angular but it worked great for me when I was having the exact same problem in React

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When you upgrade  using typescript 2 9 2   its compiler strict the rules follows for array type declare inside the component class constructor   For fix this issue either change the code where are declared in the code or avoid to compiler  to add property  strictPropertyInitialization   false in the  tsconfig json  file  and run again npm start     Angular web and mobile Application Development  you can go to www jtechweb in

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