How can I define an array of objects

Question

I am creating an array of objects in TypeScript    userTestStatus xxxx          0      id   0   name    Available          1      id   1   name    Ready          2      id   2   name    Started          Can someone tell me how I could declare its type correctly  Is it possible to do inline or would I need two definitions   I m looking to replace the xxx with a type declaration  so that later on TypeScript would alert me if I used something like userTestStatus 3  nammme by mistake

User · Answer

Array lt T gt  person  Array lt     name  string    age  number    gt

User · Answer

What you really want may simply be an enumeration  If you re looking for something that behaves like an enumeration  because I see you are defining an object and attaching a sequential ID 0  1  2 and contains a name field that you don t want to misspell  e g  name vs naaame   you re better off defining an enumeration because the sequential ID is taken care of automatically  and provides type verification for you out of the box   enum TestStatus       Available         0     Ready             1     Started           2    class Test       status  TestStatus    var test   new Test    test status   TestStatus Available     type and spelling is checked for you                                         and the sequence ID is automatic   The values above will be automatically mapped  e g   0  for  Available   and you can access them using TestStatus Available  And Typescript will enforce the type when you pass those around   If you insist on defining a new type as an array of your custom type  You wanted an array of objects   not exactly an object with keys  0    1  and  2    so let s define the type of the object  first  then a type of a containing array   class TestStatus       id  number     name  string      constructor id  name           this id   id          this name   name           type Statuses   Array lt TestStatus gt    var statuses  Statuses         new TestStatus 0   Available        new TestStatus 1   Ready        new TestStatus 2   Started

User · Answer

You can also try      interface IData          id  number          name string             let userTestStatus Record lt string IData gt               0      id   0   name    Available              1      id   1   name    Ready              2      id   2   name    Started             To check how record works  https   www typescriptlang org docs handbook utility-types html recordkt  Here in our case Record is used to declare an object whose key will be a string and whose value will be of type IData so now it will provide us intellisense when we will try to access its property and will throw type error in case we will try something like userTestStatus 0  nameee

User · Answer

Some tslint rules are disabling use of     example message  Array type using  T    is forbidden for non-simple types  Use  Array lt T gt   instead   Then you would write it like   var userTestStatus  Array lt   id  number  name  string   gt    Array         id   0   name    Available            id   1   name    Ready            id   2   name    Started

User · Answer

You are better off using a native array instead of an object literal with number-like properties  so that numbering  as well as numerous other array functions  are taken care of off-the-shelf   What you are looking for here is an inline interface definition for your array that defines every element in that array  whether initially present or introduced later   let userTestStatus    id  number  name  string                id   0   name    Available            id   1   name    Ready            id   2   name    Started        userTestStatus 34978  nammme     Error  Property  nammme  does not exist on type         If you are initializing your array with values right away  the explicit type definition is not a necessity  TypeScript can automatically infer most element types from the initial assignment   let userTestStatus            id   0   name    Available                 userTestStatus 34978  nammme     Error  Property  nammme  does not exist on type

User · Answer

var xxxx      key number   MyType

User · Answer

What you have above is an object  not an array   To make an array use    amp    to surround your objects   userTestStatus          id   0   name    Available          id   1   name    Ready          id   2   name    Started         Aside from that TypeScript is a superset of JavaScript so whatever is valid JavaScript will be valid TypeScript so no other changes are needed      Feedback clarification from OP    in need of a definition for the model posted   You can use the types defined here to represent your object model   type MyType         id  number      name  string     type MyGroupType          key string   MyType     var obj  MyGroupType          0      id   0   name    Available          1      id   1   name    Ready          2      id   2   name    Started          or if you make it an array var arr  MyType              id   0   name    Available            id   1   name    Ready            id   2   name    Started

[typescript] How can I define an array of objects?

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