It turns out the object I passed had methods, which is why the error message said `An object could not be cloned`.

In order to fix this, you can do the following:

    obj = JSON.parse(JSON.stringify(obj));
    parent.postMessage(obj, &#39;whatever&#39;);

I&#39;m working with django 1.6.5 and python 2.7.
I have import feature in my app and I get error:

    OSError: [Errno 18] Invalid cross-device link

I have problem with this part of code:

    os.rename(db_temp, settings.DATABASES[&#39;bookmat&#39;][&#39;NAME&#39;])

code in settings:

    &#39;bookmat&#39;: {
        &#39;ENGINE&#39;: &#39;django.db.backends.sqlite3&#39;,
        &#39;NAME&#39;: &#39;/my_projects/book/db/bookmat.sqlite3&#39;,
    },



OSError: [Errno 18] Invalid cross-device link

I&#39;d like to test a gRPC service written in Go. The example I&#39;m using is the Hello World server example from the [grpc-go repo][1].

The protobuf definition is as follows:

    syntax = &quot;proto3&quot;;
    
    package helloworld;
    
    // The greeting service definition.
    service Greeter {
      // Sends a greeting
      rpc SayHello (HelloRequest) returns (HelloReply) {}
    }
    
    // The request message containing the user&#39;s name.
    message HelloRequest {
      string name = 1;
    }
    
    // The response message containing the greetings
    message HelloReply {
      string message = 1;
    }

And the type in the `greeter_server` main is:

    // server is used to implement helloworld.GreeterServer.
    type server struct{}
    
    // SayHello implements helloworld.GreeterServer
    func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    	return &amp;pb.HelloReply{Message: &quot;Hello &quot; + in.Name}, nil
    }

I&#39;ve looked for examples but I couldn&#39;t find any on how to implement tests for a gRPC service in Go.

  [1]: https://github.com/grpc/grpc-go/blob/master/examples/helloworld/greeter_server/main.go

Testing a gRPC service

I&#39;m trying to call 

    parent.postMessage(obj, &#39;whatever&#39;);

 
from within an iframe and I&#39;m getting this error: `Uncaught DOMException: Failed to execute &#39;postMessage&#39; on &#39;Window&#39;: An object could not be cloned.`

Uncaught DOMException: Failed to execute &#39;postMessage&#39; on &#39;Window&#39;: An object could not be cloned

I'm trying to call
<pre><code class="hljs language-arduino">parent.postMessage(obj, 'whatever');
</code></pre>
from within an iframe and I'm getting this error: <code>Uncaught DOMException: Failed to execute 'postMessage' on 'Window': An object could not be cloned.</code>

I am receiving a bindata from the Nodejs server and now from that I need to display an image.

How can I achieve this? Is there any method to convert bindata to JPEG or any other format? Or is it possible to convert that in server and then send that image to react?

Here&#39;s how I&#39;m trying to display the binary data (`item.Image.data.data`) with an image tag:

    &lt;img src={item.Image.data.data} /&gt;

---

This is my detailed react code snippet:

    componentDidMount(){
      let self = this;
      axios.get(&#39;http://localhost:8080/list&#39;)
        .then(function(data) {
          console.log(data);
          self.setState({post:data.data});
        });
    }

    &lt;ul className=&quot;w3-ul w3-card-4 w3-light-grey&quot;&gt;
      { this.state.post.map((item, index) =&gt; {
        return (
          &lt;Link  to=&quot;/displaylist&quot; style={{ textDecoration: &#39;none&#39; }} key={index}&gt;
            &lt;li className=&quot; w3-hover-green w3-padding-16&quot; onClick={this.handleClick(item.Id)}&gt;
              &lt;img src={item.Image.data.data} className=&quot;w3-left w3-circle w3-margin-right&quot; width=&quot;60px&quot; height=&quot;40px&quot; /&gt;
              &lt;span&gt;{item.Firstname}&lt;/span&gt;&lt;br/&gt;&lt;br/&gt;
            &lt;/li&gt;
          &lt;/Link&gt;
          )}
      )}
    &lt;/ul&gt;

This is my nodejs code snippet:

    server.get(&#39;/list&#39;, function(req, res) {
        databaseInterface.listStudent(function(err, students) {
          var myJSON = students;
     
          res.json(myJSON);
          // You should see the newly saved student here
        });
    });

How to display binary data as image in React?

I have a function I want to write in React.  In my class I have a state object `fields` that looks like this:

    this.state = {
      step: 1,
      fields: {
        type: &#39;&#39;,
        name: &#39;&#39;,
        subtype: &#39;&#39;,
        team: &#39;&#39;,
        agreement: &#39;&#39;
      }
    };

I have various functions that assign those keys using `immutability helper` that generally look like:

    assignType(attribute) {
      var temp = update(this.state.fields, {
        type: {$set: attribute}
      });

      this.setState({
        fields: temp
      });
    }

What I would *like* to do is use a function that&#39;s more generic and do something like this:

    assignAttribute(field, attribute) {
      var temp = update(this.state.fields, {
        field: {$set: attribute}
      });
    
      this.setState({
        fields: temp
      });
    }

But, this doesn&#39;t work.  What can I do to use a variable key using `immutability-helper`?

Using immutability-helper in React to set variable object key

I am moving from Node.js to browser environment, and I am still confused over ArrayBuffer vs. typed arrays (such as Uint8Array).

I am confused over where to use the typed arrays, and where to use ArrayBuffer directly. It&#39;s not hard to convert one to the other and vice versa, but which to use when?

For example, when I am creating an object that will represent a chunk of data in my code, should it be ArrayBuffer or Uint8Array? What does it depend on?

Or: should I rather return `ArrayBuffer` from my functions (for example, for external API), or the typed arrays? 

Note that I can google how exactly to add elements etc to those typed arrays; what I am missing is some short general guide what to use where. Especially when moving from node&#39;s Buffer.

Where to use ArrayBuffer vs typed array in JavaScript?

I have apple and pears - both have an `isDecayed` attribute:

    interface Apple {
        color: string;
        isDecayed: boolean;
    }
    
    interface Pear {
        weight: number;
        isDecayed: boolean;
    }

And both types can be in my fruit basket (multiple times):

    interface FruitBasket {
       apples: Apple[];
       pears: Pear[];
    }


Let&#39;s assume for now my basket is empty:
   
    const fruitBasket: FruitBasket = { apples: [], pears: [] };


Now we take randomly one kind out of the basket:

    const key: keyof FruitBasket = Math.random() &gt; 0.5 ? &#39;apples&#39;: &#39;pears&#39;; 
    const fruits = fruitBasket[key];

And of course nobody likes decayed fruits so we pick only the fresh ones:
    
    const freshFruits = fruits.filter((fruit) =&gt; !fruit.isDecayed);
Unfortunately Typescript tells me:

 &gt; Cannot invoke an expression whose type lacks a call signature. Type &#39;((callbackfn: (value: Apple, index: number, array: Apple[]) =&gt; any, thisArg?: any) =&gt; Apple[]) | ...&#39; has no compatible call signatures.

What&#39;s wrong here - is it just that Typescript doesn&#39;t like fresh fruits or is this a Typescript bug?

You can try it yourself in the official [Typescript Repl][1].


  [1]: https://www.typescriptlang.org/play/#src=interface%20Apple%20%7B%0D%0A%20%20%20%20color%3A%20string%3B%0D%0A%20%20%20%20isDecayed%3A%20boolean%3B%0D%0A%7D%0D%0A%0D%0Ainterface%20Pear%20%7B%0D%0A%20%20%20%20weight%3A%20number%3B%0D%0A%20%20%20%20isDecayed%3A%20boolean%3B%0D%0A%7D%0D%0A%0D%0Ainterface%20FruitBasket%20%7B%0D%0A%20%20%20%20apples%3A%20Apple%5B%5D%3B%0D%0A%20%20%20%20pears%3A%20Pear%5B%5D%3B%0D%0A%7D%0D%0A%0D%0A%0D%0Aconst%20fruitBasket%3A%20FruitBasket%20%3D%20%7B%20apples%3A%20%5B%5D%2C%20pears%3A%20%5B%5D%20%7D%3B%0D%0Aconst%20key%3A%20keyof%20FruitBasket%20%3D%20Math.random()%20%3E%200.5%20%3F%20&#39;apples&#39;%3A%20&#39;pears&#39;%3B%20%0D%0Aconst%20fruits%20%3D%20fruitBasket%5Bkey%5D%3B%0D%0A%0D%0Aconst%20freshFruits%20%3D%20fruits.filter((fruit)%20%3D%3E%20!fruit.isDecayed)%3B

Cannot invoke an expression whose type lacks a call signature

I am swapping to Jest from Mocha, and I&#39;m wondering if there is a way to spy on a React method. For example, let&#39;s say I have the following method in my component (ignore the `sdk` library, it just constructs a jQuery Ajax call):

    getData() {
        sdk.getJSON(&#39;/someURL&#39;).done(data =&gt; {
            this.setState({data});
        });
    }

Using Sinon I would test this by spying on the prototype like so:

    it(&#39;should call getData&#39;, () =&gt; {
        sinon.spy(Component.prototype, &#39;getData&#39;);
        mount(&lt;Component /&gt;);
        expect(Component.prototype.getData.calledOnce).to.be.true;
    });

This would ensure code coverage without mocking the method. Is there similar functionality in Jest?

EDIT: Also, if this functionality doesn&#39;t exist, what is the next best strategy for testing API calls?

Content Type	Original Author	Original Content on Stackoverflow
Question	nieve	View Question on Stackoverflow
Solution 1 - Javascript	nieve	View Answer on Stackoverflow

Uncaught DOMException: Failed to execute 'postMessage' on 'Window': An object could not be cloned

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Testing a gRPC service

OSError: [Errno 18] Invalid cross-device link

Attributions