In TypeScript, a postfix `!` removes `null` and `undefined` from the type of an expression.

This is useful when you know, for reasons outside TypeScript&#39;s inference ability, that a variable that &quot;could&quot; be `null` or `undefined` actually isn&#39;t.

Working with my first application for learning purposes. It goes well but has met into a problem with Xcode. When I try to run the application on the iPhone simulator this message always pops up &quot;This app could not be installed at this time.&quot; 

[![screenshot][1]][1]

What is wrong? There are no errors when trying to build the app. Has tried to clean the build. Reinstall pods. Restarted Xcode. Erased all settings on the simulator device, however, the problems still exist. 

The error message does not give me any information. Is there another logfile I could look into or something? 


  [1]: https://i.stack.imgur.com/5Ahpd.png

Xcode: &quot;This app could not be installed at this time.&quot;

I&#39;m trying to create the back-end code for a music application on my website.

I have created the correct view in my views.py file (in the correct directory) as shown below:

    def detail(request, album_id):
        return HttpResponse(&quot;&lt;h1&gt;Details for Album ID:&quot; + str(album_id) + &quot;&lt;/h1&gt;&quot;)

However, when creating the URL or path for this (shown below)

    #/music/71/ (pk)
    path(r&#39;^(?P&lt;album_id&gt;[0-9])/$&#39;, views.detail, name=&#39;detail&#39;),

I am experiencing a warning on my terminal stating:
    
&gt; ```
&gt; ?: (2_0.W001) Your URL pattern &#39;^(?P&lt;album_id&gt;[0-9])/$&#39;
&gt; [name=&#39;detail&#39;] has a route that contains &#39;(?P&lt;&#39;, begins with a &#39;^&#39;,
&gt; or ends with a &#39;$&#39;. This was likely an oversight when migrating to
&gt; django.urls.path().
&gt; ```
And whenever the `/music/` (for which the path works) is followed by a number, such as `/music/1` (which is what I want to be able to do) the page cannot be found and the terminal gives the above warning.

Django 2.0 path error ?: (2_0.W001) has a route that contains &#39;(?P&lt;&#39;, begins with a &#39;^&#39;, or ends with a &#39;$&#39;

I&#39;ve seen in some React/TypeScript implementations such as : 

```ref={ ref =&gt; this.container = ref! }```

What does the exclamation point means in ```ref!```?
Is that something specific in TypeScript, or a new standard JavaScript notation?

What does exclamation point after variable mean in JavaScript?

I've seen in some React/TypeScript implementations such as :
<code>ref={ ref => this.container = ref! }</code>
What does the exclamation point means in <code>ref!</code>?
Is that something specific in TypeScript, or a new standard JavaScript notation?

&lt;!-- What are you trying to accomplish? (Please include sample data.) --&gt;
I&#39;m using `SafeAreaView` from React Native 0.50.1 and it&#39;s working pretty good except for the one part. I assigned the orange background color to the SafrAreaView but can&#39;t figure out to change the bottom unsafe area background to black.

Here is the code and I included expected the result and actual result.
What is the best way to make the bottom part of the screen black instead of orange?

&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-js --&gt;

    import {
      ...
      SafeAreaView
    } from &#39;react-native&#39;;
    class Main extends React.Component {
      render() {
        return (
          &lt;SafeAreaView style={styles.safeArea}&gt;
            &lt;App /&gt;
          &lt;/SafeAreaView&gt;
        )
      }
    }
    const styles = StyleSheet.create({
      ...,
      safeArea: {
        flex: 1,
        backgroundColor: &#39;#FF5236&#39;
      }
    })

&lt;!-- end snippet --&gt;

&lt;!-- Paste the part of the code that shows the problem. (Please indent 4 spaces.) --&gt;

&lt;!-- What do you expect the result to be? --&gt;
I want to have orange top and black bottom.

&lt;img src=&quot;https://i.stack.imgur.com/BZuOw.png&quot; width=&quot;150&quot;&gt;

&lt;!-- What is the actual result you get? (Please include any errors.) --&gt;
But below is what I get now.

&lt;img src=&quot;https://i.stack.imgur.com/tN8mz.png&quot; width=&quot;150&quot;&gt;

React Native SafeAreaView background color - How to assign two different background color for top and bottom of the screen?

The question is as simple as that. In Cypress, how can I access a new window that opens up when running the test.

Steps to recreate :

&gt; 1. Run the test. After some action, new window pops up (the url is dynamic in nature).
&gt; 2. Fill in the fields in the new window, and click a few buttons.
&gt; 3. After required actions are completed in the new Window, close the new window and move back to the main window.
&gt; 4. Continue execution with the main window.

Point of interest: the focus should be

    main window -&gt; new window -&gt; main window

I have read few things that relate to use of `iframe` and `confirmation box`, but here its none of those. Relates to accessing a whole new window. Something like [`Window Handlers`][1] in Selenium. Unfortunately could not find anything related to it.


  [1]: http://toolsqa.com/selenium-webdriver/switch-commands/

Access a new window - cypress.io

I have a `mapModule` where I import components and export them:

    import ComponentName from &#39;../components/ComponentName&#39;;
    
    export default {
      name: ComponentName,
    };

How can I test that `mapModule` has the correct exported keys, values and that they are not null or undefined?

Jest: how to test for object keys and values?

In a React _functional component_, which is the better approach to set default props, using `Component.defaultProps`, or using the _default parameters_ on the function definition, examples:

Default props:

    const Component = ({ prop1, prop2 }) =&gt; (
      &lt;div&gt;&lt;/div&gt;
    )

    Component.defaultProps = {
      prop1: false,
      prop2: &#39;My Prop&#39;,
    }

Default parameters:

    const Component = ({ prop1 = false, prop2 = &#39;My Prop&#39; }) =&gt; (
      &lt;div&gt;&lt;/div&gt;
    )    

React functional component default props vs default parameters

I&#39;m seeing that among the classes added to an element, sometimes there&#39;s this &#39;ng-star-inserted&#39; added as well and I&#39;d like to know more as to why is it there?

Angular 5 adds &#39;ng-star-inserted&#39; in some classes - what is that?

Let&#39;s say I have two projects with following file structure

    /my-projects/

      /project-a/
        lib.ts
        app.ts
        tsconfig.json
        
      /project-b/
        app.ts         // import &#39;../project-a/lib.ts&#39;
        tsconfig.json

**I want to consume `lib.ts` located in `project-a` also from `project-b`. How to do that?**

- Release it as **NPM module - absolutely don&#39;t want that**, it&#39;s an overkill for such a simple use case. I just 
want to share one file between two projects.

- Use `import &#39;../project-a/lib.ts&#39;` - doesn&#39;t work, TypeScript complains 

`&#39;lib.ts&#39; is not under &#39;rootDir&#39;. &#39;rootDir&#39; is expected to contain all source files.`

- Put `tsconfig.json` one level up so it would cover both `project-a` and `project-b` - can&#39;t do that, the TypeScript config is slightly different for those projects. Also it&#39;s not very convenient, don&#39;t want to do that.

Any other ways?

How to share code between TypeScript projects?

I was trying to create a `&lt;PrivateRoute&gt;` as describe in the react-router [documents][1] using TypeScript. Can anyone help me out?

**The privateRoute in react-router document:**

    const PrivateRoute = ({ component: Component, ...rest }) =&gt; (
      &lt;Route {...rest} render={props =&gt; (
        fakeAuth.isAuthenticated ? (
          &lt;Component {...props}/&gt;
        ) : (
          &lt;Redirect to={{pathname: &#39;/login&#39;, state: { from: props.location }
       }}/&gt;
      )
     )}/&gt;
    )

**Below is my TypeScript version(it won&#39;t work) :**

    const PrivateRoute = (theProps: { path: string, component: React.SFC&lt;RouteComponentProps&lt;any&gt; | undefined&gt; | React.ComponentClass&lt;RouteComponentProps&lt;any&gt; | undefined&gt; }) =&gt; {
        return &lt;Route path={theProps.path} render={props =&gt; (
            fakeAuth.isAuthenticated ? (
                &lt;React.Component {...theProps} /&gt; &lt;!-- **** It will raise error *** --&gt;
            ) : (
                    &lt;Redirect to={{
                        pathname: &#39;/&#39;,
                        state: { from: props.location }
                    }} /&gt;
                )
        )} /&gt;
    }

The `&lt;React.Component {...thisProps} /&gt;` is not right. The error is: NodeInvocationException: inst.render is not a function
TypeError: inst.render is not a function

  [1]: https://reacttraining.com/react-router/web/example/auth-workflow

How to rewrite the protected/private route using TypeScript and React-Router 4, 5 or 6?

I have the following code.

    array.map(val =&gt; { return {
      key1: val.key1,
      key2: val.key2
    }});

Is there any way to reduce the code to something like this?

    array.map(val =&gt; {
      key1: val.key1,
      key2: val.key2
    });

Typescript Array Map Return Object

I&#39;m currently using Vue.js with Typescript in a webpack project. 

As indicated in the [Recommended Configuration][1] in my `tsconfig.json` I have:

 ` &quot;strict&quot;: true,`

Inside one of my component i have:

    declare interface Player {
        cod: string,
        param: string
      }

    export default Vue.extend({
        name: &#39;basecomponent&#39;,
        data() {
          return {
            players: []
          };
        },
        created() 
          let self = this
          axios.get(&#39;fetch-data&#39;)
            .then((response) =&gt; {
              let res: Players[] = response.data;
              for(let i = 0; i &lt; res.length; i++){
                  self.players.push(res[i]);
              }
            })
            .catch((error: string) =&gt; {
              console.log(error);
           });
        },
     });

but when I try to compile i get:

     error TS2345: Argument of type &#39;Player&#39; is not assignable to parameter of type &#39;never&#39;.

Cause I believe ` players: []` has `never[]` type.

My question is: how can I infer type Vue data object properties??

  [1]: https://vuejs.org/v2/guide/typescript.html


Set data Type in Vue data object with Typescript

Hello guys I&#39;m trying to find all the results that have a in them. I have tried a couple of ways but the problem is nothing works. It just returns an empty array 

```js
var data = await getRepository(User)
  .createQueryBuilder(&quot;user&quot;)
  .where(&quot;user.firstName = %:name%&quot;, { name: firstName })
  .getMany();
```

and something like this 

```js
var data = await getRepository(User)
  .createQueryBuilder(&quot;user&quot;)
  .where(&quot;user.firstName like %:name%&quot;, { name: firstName })
  .getMany();
```

but nothing is working. All of these are returning me a empty array. Can somebody help me out thanks 

Content Type	Original Author	Original Content on Stackoverflow
Question	dbrrt	View Question on Stackoverflow
Solution 1 - Javascript	Ryan Cavanaugh	View Answer on Stackoverflow

What does exclamation point after variable mean in JavaScript?

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Django 2.0 path error ?: (2_0.W001) has a route that contains '(?P<', begins with a '^', or ends with a '$'

Xcode: "This app could not be installed at this time."

Attributions