Get an object s class name at runtime

Question

Is it possible to get an object s class type name at runtime using TypeScript   class MyClass    var instance   new MyClass    console log instance           Should output  MyClass

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See this question    Since TypeScript is compiled to JavaScript  at runtime you are running JavaScript  so the same rules will apply

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The full TypeScript code   public getClassName         var funcNameRegex    function    1            var results     funcNameRegex  exec this  constructor   toString         return  results  amp  amp  results length  gt  1    results 1

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Simple answer    class MyClass     const instance   new MyClass     console log instance constructor name      MyClass console log MyClass name                   MyClass   However  beware that the name will likely be different when using minified code

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I know I m late to the party  but I find that this works too   var constructorString  string   this constructor toString    var className  string   constructorString match   w  g  1        Alternatively     var className  string   this constructor toString   match   w  g  1       The above code gets the entire constructor code as a string and applies a regex to get all  words   The first word should be  function  and the second word should be the name of the class   Hope this helps

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Had to add   prototype   to use   myClass prototype constructor name   Otherwise with the following code    myClass constructor name  I had the TypeScript error        error TS2339  Property  name  does not exist on type  Function

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In Angular2  this can help to get components name      getName             let comp any   this constructor          return comp name         comp any is needed because TypeScript compiler will issue errors since Function initially does not have property name

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My solution was not to rely on the class name  object constructor name works in theory  But if you re using TypeScript in something like Ionic  as soon as you go to production it s going to go up in flames because Ionic s production mode minifies the Javascript code  So the classes get named things like  a  and  e     What I ended up doing was having a typeName class in all my objects that the constructor assigns the class name to  So   export class Person   id  number  name  string  typeName  string   constructor     typeName    Person       Yes that wasn t what was asked  really  But using the constructor name on something that might potentially get minified down the road is just begging for a headache

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You need to first cast the instance to any because Function s type definition does not have a name property   class MyClass     getName         return   lt any gt this  constructor name         OR return  this as any  constructor name            From outside the class  var className     lt any gt new MyClass    constructor name     OR var className    new MyClass   as any  constructor name  console log className      Should output  MyClass      From inside the class  var instance   new MyClass    console log instance getName        Should output  MyClass    Update   With TypeScript 2 4  and potentially earlier  the code can be even cleaner   class MyClass     getName         return this constructor name            From outside the class  var className    new MyClass  constructor name  console log className      Should output  MyClass      From inside the class  var instance   new MyClass    console log instance getName        Should output  MyClass

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If you already know what types to expect  for example  when a method returns a union type   then you can use type guards   For example  for primitive types you can use a typeof guard   if  typeof thing      number          Do stuff     For complex types you can use an instanceof guard   if  thing instanceof Array         Do stuff

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Solution using Decorators that survives minification uglification We use code generation to decorate our Entity classes with metadata like so   name  Customer   export class Customer     public custId  string    public name  string     Then consume with the following helper  export const nameKey   Symbol  name            To perserve class name though mangling      example     name  Customer      class Customer        param className     export function name className  string   ClassDecorator     return  Reflect as any  metadata nameKey  className              example    const type   Customer     getName type       Customer      param type     export function getName type  Function   string     return  Reflect as any  getMetadata nameKey  type              example    const instance   new Customer       getInstanceName instance       Customer      param instance     export function getInstanceName instance  Object   string     return  Reflect as any  getMetadata nameKey  instance constructor      Extra info   You may need to install reflect-metadata reflect-metadata is pollyfill written by members ot TypeScript for the proposed ES7 Reflection API The proposal for decorators in JS can be tracked here

[typescript] Get an object's class name at runtime

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