You also can do

    Array.from(my_set.values());

# Fix 

* Use tsconfig.json with `&quot;lib&quot;: [&quot;es6&quot;]`

# More 

* Google `lib` option. 
* I wrote some docs too : https://basarat.gitbooks.io/typescript/content/docs/types/lib.d.ts.html#lib-option

if you declare your set this way:

    const mySet = new Set&lt;string&gt;();

 you will be able to easily use:

    let myArray = Array.from( mySet );


or simply 

    const mySet = new Set&lt;string&gt;();
    mySet.add(1);
    mySet.add(2);
    console.log([...mySet.values()]);

@basarat&#39;s answer wasn&#39;t sufficient in my case: I couldn&#39;t use the spread operator despite having `esnext` in my `lib` array.

To correctly enable using the spread operator on sets and other ES2015 iterables, I had to enable the `downlevelIteration` compiler option.

Here&#39;s how to set it via `tsconfig.json`:

```json
{
  &quot;compilerOptions&quot;: {
    &quot;downlevelIteration&quot;: true
  }
}
```

You will find a more detailed explanation of this flag in the [TS documentation page about compiler options](https://www.typescriptlang.org/docs/handbook/compiler-options.html#compiler-options).

Another solution is using the `!` post-fix expression operator to assert that its operand is non-null and non-undefined.

&gt; You&#39;ll find further information in [Non-null assertion operator][1]

You can use the spread operator to convert a Set into an Array: 

    const mySet = new Set([&#39;h&#39;,&#39;j&#39;,&#39;l&#39;,&#39;l&#39;]);
    console.log([...mySet!])


  [1]: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-0.html#non-null-assertion-operator

I see that the Android Plugin for Gradle has a `minifyEnabled` property as well as a `useProguard` property, as follows:

    android {
        buildTypes {
            debug {
                minifyEnabled true
                useProguard false
            }
            release {
                minifyEnabled true
                useProguard true
            }
        }
    }

What&#39;s the difference between these two properties? Or, rather, what&#39;s the meaning of each?

What&#39;s the difference between &quot;minifyEnabled&quot; and &quot;useProguard&quot; in the Android Plugin for Gradle?

In different Kotlin examples for Android I see `toast(&quot;Some message...&quot;)` or `toastLong(&quot;Some long message&quot;)`. For example:

    view.setOnClickListener { toast(&quot;Click&quot;) }

As I understand, it is an Extension Function for `Activity`.

How and where do you define this `toast()` function so that you are able to use it throughout the project?

How do you display a Toast using Kotlin on Android?

How can I convert a Set (eg, {2,4,6}) to an Array [2, 4, 6] in TypeScript without writing a loop explicitly ?

I have tried those following ways, all of them work in JavaScript but none of them work on TypeScript

    [...set] // ERR: &quot;Type &#39;Set&lt;{}&gt;&#39; is not an array type&quot; in typescript
    
    Array.from(set) // ERR: Property &#39;from&#39; does not exist on type &#39;ArrayConstructor&#39;

How can I convert a Set to an Array in TypeScript

How can I convert a Set (eg, {2,4,6}) to an Array [2, 4, 6] in TypeScript without writing a loop explicitly ?
I have tried those following ways, all of them work in JavaScript but none of them work on TypeScript
<pre><code class="hljs language-python">[...set] // ERR: "Type 'Set&#x3C;{}>' is not an array type" in typescript

Array.from(set) // ERR: Property 'from' does not exist on type 'ArrayConstructor'
</code></pre>

I know that in C we cannot return an array from a function, but a pointer to an array. But I want to know what is the special thing about `structs` that makes them return-able by functions even though they may contain arrays.

Why is the `struct` wrapping makes the following program valid?

	#include &lt;stdio.h&gt;

	struct data {
		char buf[256];
	};

	struct data Foo(const char *buf);

	int main(void)
	{
		struct data obj;
		obj = Foo(&quot;This is a sentence.&quot;);
		printf(&quot;%s\n&quot;, obj.buf);
		return 0;
	}

	struct data Foo(const char *buf)
	{
		struct data X;
		strcpy(X.buf, buf);
		return X;
	}

What is special about structs?

I have always found the `range` function missing from JavaScript as it is available in python and others? Is there any concise way to generate range of numbers in ES2015 ?

EDIT: MY question is different from the mentioned duplicate as it is specific to ES2015 and not ECMASCRIPT-5. Also I need the range to be starting from 0 and not specific starting number (though it would be good if that is there)

How to generate range of numbers from 0 to n in ES2015 only?

Inspired by a program described in *K&amp;R* section 5.5:

    void strcpy(char *s, char *t)
    {
    	while(*s++ = *t++);
    }


C program

	if (&#39;\0&#39;) { printf(&quot;\&#39;\\0\&#39; -&gt; true \n&quot;); }
	else      { printf(&quot;\&#39;\\0\&#39; -&gt; false\n&quot;); }

	if (&quot;\0&quot;) { printf(&quot;\&quot;\\0\&quot; -&gt; true \n&quot;); }
	else      { printf(&quot;\&quot;\\0\&quot; -&gt; false\n&quot;); }

prints

    &#39;\0&#39; -&gt; false
    &quot;\0&quot; -&gt; true
Why do `&#39;\0&#39;` and `&quot;\0&quot;` evaluate differently in C?

&gt; clang version 3.8.0

&#39;\0&#39; evaluates false, &quot;\0&quot; evaluates true

ng-2 parent-child data inheritance has been a difficulty for me. 

What seems that could be a fine working practical solution is filtering my total array of data to an array consisting of only child data referenced by a single parent id.
In other words: data-inheritance becomes data filtering by one parent id. 

In a concrete example this can look like: filtering a books array to only show the books with a certain `store_id`.

&lt;!-- begin snippet: js hide: false --&gt;

&lt;!-- language: lang-ts --&gt;

    import {Component, Input} from &#39;angular2/core&#39;;

    export class Store {
      id: number;
      name: string;
    }

    export class Book {
      id: number;
      shop_id: number;
      title: string;
    }

    @Component({
      selector: &#39;book&#39;,
      template:`
        &lt;p&gt;These books should have a label of the shop: {{shop.id}}:&lt;/p&gt;

        &lt;p *ngFor=&quot;#book of booksByShopID&quot;&gt;{{book.title}}&lt;/p&gt;
      `
    ])
    export class BookComponent {
      @Input()
      store: Store;

      public books = BOOKS;

      // &quot;Error: books is not defined&quot;
      // ( also doesn&#39;t work when books.filter is called like: this.books.filter
      // &quot;Error: Cannot read property &#39;filter&#39; of undefined&quot; )
      var booksByStoreID = books.filter(book =&gt; book.store_id === this.store.id)
    }

    var BOOKS: Book[] = [
      { &#39;id&#39;: 1, &#39;store_id&#39;: 1, &#39;name&#39;: &#39;Dichtertje&#39; },
      { &#39;id&#39;: 2, &#39;store_id&#39;: 1, &#39;name&#39;: &#39;De uitvreter&#39; },
      { &#39;id&#39;: 3, &#39;store_id&#39;: 2, &#39;name&#39;: &#39;Titaantjes&#39; }
    ];

&lt;!-- end snippet --&gt;

TypeScript is new to me, but I think I am close to making things work here.

(Also overwriting the original books array could be an option, then using `*ngFor=&quot;#book of books&quot;`.)

**EDIT**
Getting closer, but still giving an error.

&lt;!-- begin snippet: js hide: false --&gt;

&lt;!-- language: lang-ts --&gt;

    //changes on top:
    import {Component, Input, OnInit} from &#39;angular2/core&#39;;

    // ..omitted

    //changed component:
    export class BookComponent implements OnInit {
      @Input() 
      store: Store;

      public books = BOOKS;

      // adding the data in a constructor needed for ngInit
      // &quot;EXCEPTION: No provider for Array!&quot;
      constructor(
        booksByStoreID: Book[];
      ) {}


      ngOnInit() {
        this.booksByStoreID = this.books.filter(
          book =&gt; book.store_id === this.store.id);
      }
    }

    // ..omitted

&lt;!-- end snippet --&gt;



How do I filter an array with TypeScript in Angular 2?

I&#39;m trying to make an array that if a value doesn&#39;t exist then it is added but however if the value is there I would like to remove that value from the array as well. 

Feels like Lodash should be able to do something like this. 

I&#39;m interested in your best practises suggestions. 

Also it is worth pointing out that I am using Angular.js

*** Update *** 

    if (!_.includes(scope.index, val)) {
        scope.index.push(val);
    } else {
      _.remove(scope.index, val);
    }

Using lodash push to an array only if value doesn&#39;t exist?

In one of my Angular 2 routes&#39;s templates (**FirstComponent**) I have a button

**first.component.html**

    &lt;div class=&quot;button&quot; click=&quot;routeWithData()&quot;&gt;Pass data and route&lt;/div&gt;

My **goal** is to achieve:

&gt; Button click -&gt; route to another component while preserving data and without using the other component as a directive.

This is what I tried...

**1ST APPROACH**

In the same view I am storing collecting same data based on user interaction.

**first.component.ts**

    export class FirstComponent {
         constructor(private _router: Router) { }

         property1: number;
         property2: string;
         property3: TypeXY; // this a class, not a primitive type

        // here some class methods set the properties above

        // DOM events
        routeWithData(){
             // here route
        }
    }

Normally I&#39;d route to **SecondComponent** by

     this._router.navigate([&#39;SecondComponent&#39;]);

eventually passing the data by

     this._router.navigate([&#39;SecondComponent&#39;, {p1: this.property1, p2: property2 }]);

whereas the definition of the link with parameters would be 

    @RouteConfig([
          // ...
          { path: &#39;/SecondComponent/:p1:p2&#39;, name: &#39;SecondComponent&#39;, component: SecondComponent} 
    )]

The issue with this approach is that I guess **I can&#39;t pass complex data** (e.g. an **object** like property3) in-url;

**2ND APPROACH**

An alternative would be including SecondComponent as **directive** in FirstComponent.

      &lt;SecondComponent [p3]=&quot;property3&quot;&gt;&lt;/SecondComponent&gt;

However I want to **route** to that component, not include it!

**3RD APPROACH**

The most viable solution I see here would be to use a **Service** (e.g. FirstComponentService) to 

- **store** the data (_firstComponentService.storeData()) on routeWithData() in FirstComponent
- **retrieve** the data (_firstComponentService.retrieveData()) in **ngOnInit()** in **SecondComponent**

While this approach seems perfectly viable, I wonder whether this is the easiest / most elegant way to achieve the goal.

In general I&#39;d like to know whether I&#39;m missing other **potential approaches** to pass the data between components, particularly **with the less possible amount of code**

How do I pass data to Angular routed components?

I have a simple union type of string literals and need to check it&#39;s validity because of FFI calls to &quot;normal&quot; Javascript. Is there a way to ensure that a certain variable is an instance of any of those literal strings **at runtime**? Something along the lines of

    type MyStrings = &quot;A&quot; | &quot;B&quot; | &quot;C&quot;;
    MyStrings.isAssignable(&quot;A&quot;); // true
    MyStrings.isAssignable(&quot;D&quot;); // false

Checking validity of string literal union type at runtime?

As far as I know a property&#39;s type can be defined in two ways when it&#39;s an Array.

    property_name: type

where type can be either

    Array&lt;string&gt;, Array&lt;MyType&gt;, etc. (e.g. let prop1: Array&lt;string&gt;)

and

    string[], MyType[], etc. (e.g. let prop1: string[])

What is the **difference** between the two cases? Or am I misunderstanding something (perhaps something about &lt;&gt; used in casting?)

**EDIT** since the question is marked as duplicate, I am aware there is the other question about any[] but still I had a look at it before posting and to me it was more about the type &#39;any&#39; than the different [] VS &lt;&gt; I asked

Array&lt;Type&gt; VS Type[] in Typescript

What is the difference between `private` and `protected` variables in TypeScript? Similar questions exist for `C#` but I am not sure if the concepts in the two languages are identical. If not, it would be useful to know the differences.

TypeScript - Difference between Private and Protected Variables

Let&#39;s say I have an interface:

    interface IUser {
      email: string;
      id: number;
      phone: string;
    };

Then I have a function that expects a **subset** (or complete match) of that type. Maybe it will pass an entire object, made it will just pass in `{email: &quot;t@g.com&quot;}`. I want the type checker to allow for both.

Example:

    function updateUser(user: IUser) {
      // Update a &quot;subset&quot; of user attributes:
      $http.put(&quot;/users/update&quot;, user);
    }

Does Typescript support this sort of behavior yet? I could find it very useful, particularly with paradigms like Redux.

To clarify, the goal is:

1. Avoid re-writing an interface and manually setting all attributes to optional.
2. Avoid assignment of unexpected attributes (such as spelling mistakes).
3. Avoid imperative logic such as `if` statements, which forfeit benefits of compile time type checking.

**UPDATE:** Typescript has announced support for [mapped types](https://github.com/Microsoft/TypeScript/pull/12114) which should solve this problem once published.

Does Typescript support &quot;subset types&quot;?

How can I use `collect_set` or `collect_list` on a dataframe after `groupby`. for example: `df.groupby(&#39;key&#39;).collect_set(&#39;values&#39;)`. I get an error: `AttributeError: &#39;GroupedData&#39; object has no attribute &#39;collect_set&#39;
`

pyspark collect_set or collect_list with groupby

I can&#39;t understand the logic behind the terms *union types* and *intersection types* in TypeScript.

Pragmatically, if the properties of different types are sets of properties, if I combine them with the `&amp;` operator, the resulting type will be the *union* of the of those sets. Following that logic, I would expect types like this to be called *union types*. If I combine them with `|`, I can only use the common properties of them, the *intersection* of the sets.

[Wikipedia](https://en.wikipedia.org/wiki/Boolean_algebra_(structure)#Examples) seems to back that logic:
&gt; The power set (set of all subsets) of any given nonempty set S forms a Boolean algebra, an algebra of sets, with the two operations ∨ := ∪ (union) and ∧ := ∩ (intersection).

However, according to [typescriptlang.org](https://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types), it&#39;s exactly the opposite: `&amp;` is used to produce *intersection types* and `|` is used for *union types*.

I&#39;m sure there is another way of looking at it, but I cannot figure it out.

Naming of TypeScript&#39;s union and intersection types

It maybe because Sets are relatively new to Javascript but I haven&#39;t been able to find an article, on StackO or anywhere else, that talks about the performance difference between the two in Javascript. So, what is the difference, in terms of performance, between the two? Specifically, when it comes to removing, adding and iterating.

Javascript Set vs. Array performance

Why does the `set` function call wipe out the dupes, but parsing a set literal does not?

    &gt;&gt;&gt; x = Decimal(&#39;0&#39;)
    &gt;&gt;&gt; y = complex(0,0)
    &gt;&gt;&gt; set([0, x, y])
    {0}
    &gt;&gt;&gt; {0, x, y}
    {Decimal(&#39;0&#39;), 0j}

(Python 2.7.12.  Possibly same root cause as for [this][1] similar question)


  [1]: https://stackoverflow.com/q/40225520/674039

Set literal gives different result from set function call

How come when I change the order of the two sets in the unions below, I get different results?

    set1 = {1, 2, 3}
    set2 = {True, False}

    print(set1 | set2)
    # {False, 1, 2, 3}

    print(set2 | set1)
    #{False, True, 2, 3}



Union of 2 sets does not contain all items

I am trying to call an API from Angular but am getting this error:

`Property &#39;map&#39; does not exist on type &#39;Observable&lt;Response&gt;&#39;`

The answers from this similar question didn&#39;t solve my issue: https://stackoverflow.com/questions/36947748/angular-2-beta-17-property-map-does-not-exist-on-type-observableresponse. 

I am using Angular 2.0.0-beta.17.

Property &#39;map&#39; does not exist on type &#39;Observable&lt;Response&gt;&#39;

I want to define several interfaces in their own file in my typescript-based project, from which I&#39;ll implement classes for production as well as mocks for testing. However, I can&#39;t figure out what the correct syntax is. I&#39;ve found plenty of tutorials on declaring interfaces and implementing them, but they all have a trivial implementation of both the interface and derived classes in the same file, which isn&#39;t very real-world. What&#39;s the right way to export and import the interfaces?





How to declare and import typescript interfaces in a separate file

I recently installed Typescript 1.8 and found too many breaking issues.
So for the time being I would like to install 1.7.
Where can I get a link to down this?


How to install older version of Typescript?

I have a set of angular2 components that should all get some service injected. My first thought was that it would be best to create a super class and inject the service there. Any of my components would then extend that superclass but this approach does not work.

Simplified example:

    export class AbstractComponent {
      constructor(private myservice: MyService) {
        // Inject the service I need for all components
      }
    }
    
    export MyComponent extends AbstractComponent {
      constructor(private anotherService: AnotherService) {
        super(); // This gives an error as super constructor needs an argument
      }
    }

I could solve this by injecting `MyService` within each and every component and use that argument for the `super()` call but that&#39;s definetly some kind of absurd.

How to organize my components correctly so that they inherit a service from the super class?

Inheritance and dependency injection

Trying to have some basic understanding about module and target.  

I would like to know the difference between module and target compile options in a typical tsconfig.json

&lt;pre&gt;
{
    &quot;compilerOptions&quot;: {
    	&quot;module&quot;: &quot;es6&quot;,
        &quot;sourceMap&quot;: true,
        &quot;target&quot;: &quot;es6&quot;
    }
}
&lt;/pre&gt;

What happens if I provide the following options:

module: commonjs, target: es6

module: es6, target: commonjs

module: commonjs, target: commonjs

Content Type	Original Author	Original Content on Stackoverflow
Question	thanhpk	View Question on Stackoverflow
Solution 1 - Arrays	mayan anger	View Answer on Stackoverflow
Solution 2 - Arrays	basarat	View Answer on Stackoverflow
Solution 3 - Arrays	OhadR	View Answer on Stackoverflow
Solution 4 - Arrays	guzmanoj	View Answer on Stackoverflow
Solution 5 - Arrays	Francesco Mastellone	View Answer on Stackoverflow
Solution 6 - Arrays	Hugo Ramirez	View Answer on Stackoverflow

How can I convert a Set to an Array in TypeScript

Arrays Problem Overview

Arrays Solutions

Solution 1 - Arrays

Solution 2 - Arrays

Fix

More

Solution 3 - Arrays

Solution 4 - Arrays

Solution 5 - Arrays

Solution 6 - Arrays

How do you display a Toast using Kotlin on Android?

What's the difference between "minifyEnabled" and "useProguard" in the Android Plugin for Gradle?

Attributions