To do this in Chrome Dev tools you can use the Geolocation sensor emulation.
Go to the 3 dotted menu, More Tools and Sensors.

There&#39;s a Geolocation dropdown with some common locations but you can change your preferred one as well. To do that you can choose **Other...** in that dropdown and enter a custom **Timezone ID**

Here&#39;s a demo page to test it: https://mathiasbynens.be/demo/timezone
and a video that shows the procedure: https://www.youtube.com/watch?v=pIpN_AuV4AI

[![Timezone testing in Chrome developer tools][1]][1]


  [1]: https://i.stack.imgur.com/RuLGH.png

**2020 update**: see the other answer, which shows the result of a [feature request](https://bugs.chromium.org/p/chromium/issues/detail?id=993628) I filed with Chromium to implement a way to override the timezone.

Note that the technique only works to change the location (including timezone) *in that tab*. Other tabs will still use the system&#39;s timezone. DevTools isn&#39;t a reliable way to spoof your timezone.

To change the timezone **for all tabs in the browser** (Chrome or Firefox or whatever), on Linux/MacOS, you can launch the browser with the `TZ` environment variable set to the desired [timezone name](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones):

    TZ=America/New_York chromium-browser

I read on many forums that the problem of select and multiselect has been resolved after the beta version of bootstrap 4.

Unfortunately I am unable to display the multiselect as in ([bootstrap 3][1]) in ([bootstrap 4][2]).

**Bootstrap 3 Snippet**

&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-js --&gt;

    $(&#39;select&#39;).selectpicker();

&lt;!-- language: lang-html --&gt;

    &lt;script src=&quot;https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js&quot;&gt;&lt;/script&gt;
    &lt;link rel=&quot;stylesheet&quot; href=&quot;https://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css&quot;&gt;
    &lt;link rel=&quot;stylesheet&quot; href=&quot;https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.8.1/css/bootstrap-select.css&quot;&gt;
    &lt;script src=&quot;https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.8.1/js/bootstrap-select.js&quot;&gt;&lt;/script&gt;
    &lt;script src=&quot;https://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js&quot;&gt;&lt;/script&gt;

    &lt;select class=&quot;selectpicker&quot; multiple data-live-search=&quot;true&quot;&gt;
      &lt;option&gt;Mustard&lt;/option&gt;
      &lt;option&gt;Ketchup&lt;/option&gt;
      &lt;option&gt;Relish&lt;/option&gt;
    &lt;/select&gt;

&lt;!-- end snippet --&gt;

**Bootstrap 4 Snippet**

&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-js --&gt;

    $(&#39;select&#39;).selectpicker();

&lt;!-- language: lang-html --&gt;

    &lt;script src=&quot;https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js&quot;&gt;&lt;/script&gt;
    &lt;link rel=&quot;stylesheet&quot; href=&quot;https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css&quot;&gt;
    &lt;script src=&quot;https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.bundle.min.js&quot;&gt;&lt;/script&gt;

    &lt;select class=&quot;selectpicker&quot; multiple data-live-search=&quot;true&quot;&gt;
      &lt;option&gt;Mustard&lt;/option&gt;
      &lt;option&gt;Ketchup&lt;/option&gt;
      &lt;option&gt;Relish&lt;/option&gt;
    &lt;/select&gt;

&lt;!-- end snippet --&gt;

  [1]: https://jsfiddle.net/Pension007/had1ws54/1/
  [2]: https://jsfiddle.net/Pension007/xsvw4659/1/

Bootstrap 4 multiselect dropdown

I have been trying to understand the new React Context API and was playing with it. I just wanted to check a simple case - what all re-renders when data to a Provider is updated. 

Check **[this small example on Codesandbox][1]**

So, in my example, I have an `App` component - that has state something like this -- 

    this.state = {
      number - A random number
      text - A static text
    } 

I create a new React Context from here containing `number` and `text` from state and pass the values to two Consumers `Number` and `Text`.

So my assumption is if the random number updates, it will change the context and both the components should trigger re-render. 

But in reality, the value is updating but no rerender is happening.

So, my question -
 
1. Are updated to the context not propagated via the ususal rerenders? As I cannot see my logs / color changes when context changes. 


2. Are all the consumers to that Provider updated or not?


  [1]: https://codesandbox.io/s/l2kx18n35z

Does new React Context API trigger re-renders?

I&#39;ve created a tool in JavaScript that determines the current UTC time and checks if another predetermined date has passed yet. 

I&#39;d like to change my browser to another timezone and see if the tests still pass but I&#39;m having trouble finding a way to do this. 

Is there a way to do this in Chrome dev tools? If not, do any other suggestions come to mind?

Is there a way to change your timezone in Chrome devtools?

I've created a tool in JavaScript that determines the current UTC time and checks if another predetermined date has passed yet.
I'd like to change my browser to another timezone and see if the tests still pass but I'm having trouble finding a way to do this.
Is there a way to do this in Chrome dev tools? If not, do any other suggestions come to mind?

I&#39;m trying to create a click event be able to delete an item on my list, but when I click it I get &quot;TypeError: Cannot read property &#39;props&#39; of undefined&quot;.

I&#39;m trying to stick to ES6 as much as possible, and I&#39;m pretty sure its something to do binding &#39;this&#39; somewhere, but I&#39;ve tried many places and been unsuccessful.

    import React, { Component } from &#39;react&#39;;
    import &#39;./App.css&#39;;
    
    class App extends Component {
        render() {
            return (
                &lt;div className=&quot;App&quot;&gt;
                    &lt;StreetFighter /&gt;
                &lt;/div&gt;
            );
        }
    }
    
    class StreetFighter extends Component {
        constructor(props) {
            super(props);
            this.state = {
                characters: [
                    &#39;Chun-Li&#39;,
                    &#39;Guile&#39;,
                    &#39;Ryu&#39;,
                    &#39;Ken&#39;,
                    &#39;E.Honda&#39;,
                    &#39;Dhalsim&#39;,
                ],
            };
        }
        render() {
            let characters = this.state.characters;
            characters = characters.map((char, index) =&gt; {
                return (
                    &lt;Character char={char} key={index} onDelete={this.onDelete} /&gt;
                );
            });
            return (
                &lt;div&gt;
                    &lt;p&gt;Street Fighter Characters&lt;/p&gt;
                    &lt;ul&gt;{characters}&lt;/ul&gt;
                &lt;/div&gt;
            );
        }
        onDelete(chosenCharacter) {
            let updatedCharactersList = this.state.characters.filter(
                (char, index) =&gt; {
                    return chosenCharacter !== char;
                }
            );

            this.setState({
                characters: updatedCharactersList,
            });
        }
    }
    
    class Character extends Component {
        render() {
            return (
                &lt;li&gt;
                    &lt;div className=&quot;character&quot;&gt;
                        &lt;span className=&quot;character-name&quot;&gt;{this.props.char}&lt;/span&gt;
                        &lt;span
                            className=&quot;character-delete&quot;
                            onClick={this.handleDelete}
                            &gt; x &lt;/span&gt;
                    &lt;/div&gt;
                &lt;/li&gt;
            )
        };
    
        handleDelete() {
            this.props.onDelete(this.props.char);
        }
    }
    
    
    export default App;



React - TypeError: Cannot read property &#39;props&#39; of undefined

Recently I came across this question: https://stackoverflow.com/questions/50673012/assignment-operator-chain-understanding.

While answering this question I started doubting my own understanding of the behavior of the addition assignment operator `+=` or any other `operator=` (`&amp;=`, `*=`, `/=`, etc.).

My question is, when is the variable `a` in the expressions below updated in place, so that its changed value is reflected in other places in the expression during evaluation, and what is the logic behind it? Please take a look at following two expressions:

**Expression 1**

    a = 1
    b = (a += (a += a))
    //b = 3 is the result, but if a were updated in place then it should&#39;ve been 4

**Expression 2**

    a = 1
    b = (a += a) + (a += a)
    //b = 6 is the result, but if a is not updated in place then it should&#39;ve been 4

In the first expression, when the innermost expression `(a += a)` is evaluated, it seems that it doesn&#39;t update value of `a`, thus the result comes out as `3` instead of `4`.

However, in the second expression, the value of `a` is updated and so the result is 6.

When should we assume that `a`&#39;s value will be reflected in other places in the expression and when should we not?

Addition assignment += behavior in expression

I have called third party API using Jquery AJAX. I am getting following error in console:

&gt;Cross-Origin Read Blocking (CORB) blocked cross-origin response **MY URL** with MIME type application/json. See https://www.chromestatus.com/feature/5629709824032768 for more details.

I have used following code for Ajax call : 

    $.ajax({
      type: &#39;GET&#39;,
      url: My Url,
      contentType: &#39;application/json&#39;,
      dataType:&#39;jsonp&#39;,
      responseType:&#39;application/json&#39;,
      xhrFields: {
        withCredentials: false
      },
      headers: {
        &#39;Access-Control-Allow-Credentials&#39; : true,
        &#39;Access-Control-Allow-Origin&#39;:&#39;*&#39;,
        &#39;Access-Control-Allow-Methods&#39;:&#39;GET&#39;,
        &#39;Access-Control-Allow-Headers&#39;:&#39;application/json&#39;,
      },
      success: function(data) {
        console.log(data);
      },
      error: function(error) {
        console.log(&quot;FAIL....=================&quot;);
      }
    });

When I checked in Fiddler, I have got the data in response but not in Ajax success method.

Please help me out.

Cross-Origin Read Blocking (CORB)

The old school way of adding all values of an array into the `Set` is:

    // for the sake of this example imagine this set was created somewhere else 
    // and I cannot construct a new one out of an array
    let mySet = new Set()

    for(let item of array) {
      mySet.add(item)
    }

Is there a more elegant way of doing this? Maybe `mySet.add(array)` or `mySet.add(...array)`?

PS: I know both do not work

How to add an array of values to a Set

Up to this point, I thought &quot;calling&quot; and &quot;invoking&quot; a function meant the same thing. However, in a YouTube tutorial it said to invoke a function *by calling it*. My first thought was that the wording was a mistake, but on W3Schools&#39; [page][1] on Function Invocation, it says: 

&gt; It is common to use the term &quot;call a function&quot; instead of &quot;invoke a
&gt; function&quot; ... In this tutorial, we will use invoke, because a
&gt; JavaScript function can be invoked without being called.

Okay, so there&#39;s a difference. What is it?


  [1]: https://www.w3schools.com/js/js_function_invocation.asp

Calling vs invoking a function

When I `apt-get update` and `apt-get upgrade` my Ubuntu system, I get the following error message regarding fetching Google Chrome updates.  This only started happening a few days ago.

&lt;!-- language: bash --&gt;

    E: Repository &#39;http://dl.google.com/linux/chrome/deb stable Release&#39; changed its &#39;Origin&#39; value from &#39;Google, Inc.&#39; to &#39;Google LLC&#39;
    N: This must be accepted explicitly before updates for this repository can be applied. See apt-secure(8) manpage for details.

The error message clearly shows that this has to do with [Google changing its name][1] from *Google, Inc* to Google *LLC*.  The error message shows what&#39;s wrong, but does not tell us what command to run to fix this problem.

How can I accept this change explicitly as the message says?

[1]: https://techcrunch.com/2017/09/04/google-parent-alphabet-forms-holding-company-xxvi-to-complete-2015-corporate-reorganization/

E: Repository &#39;http://dl.google.com/linux/chrome/deb stable Release&#39; changed its &#39;Origin&#39; value from &#39;Google, Inc.&#39; to &#39;Google LLC&#39;

This was working fine up until yesterday. Now when I connect my Android device for USB Debuggers. Chrome is no longer display my app. 

Now the popup window shows HTTP/1.1 404 Not Found.

Looks to be connecting fine and the app runs fine on my Mobile Device.

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/3OthL.png

Google Chrome Developer Tools : Android Debugging returns HTTP/1.1 404 Not Found. Why?

Why is `navigator.clipboard` always `undefined` in the following snippet?

	var clipboard = navigator.clipboard;
	if (clipboard == undefined) {
		console.log(&#39;clipboard is undefined&#39;);
	} else {
		clipboard.writeText(&#39;stuff to write&#39;).then(function() {
			console.log(&#39;Copied to clipboard successfully!&#39;);
		}, function() {
			console.error(&#39;Unable to write to clipboard. :-(&#39;);
		});
	}

More on the clipboard API can be found [here][1].

Chrome Version: 68.0.3440.106.

I&#39;m sure this was working at some point, but no longer is.  It&#39;s confusing because [this table][2] suggests that the Clipboard API is implemented in Chrome (has been for some time), but [this table][3] of specific API methods suggests that none of the methods of the API is supported??


  [1]: https://www.w3.org/TR/clipboard-apis/#h-clipboard-writetext-data
  [2]: https://developer.mozilla.org/en-US/docs/Web/API/Clipboard_API#Browser_Compatibility
  [3]: https://developer.mozilla.org/en-US/docs/Web/API/Clipboard#Browser_Compatibility

navigator.clipboard is undefined

since the new update of Google Chrome (version 69.0.3497.92 (official build) (64-bit)) I can&#39;t find the serviceWorker service in the Navigator anymore. Actually I could register my Service Worker as follows but now I get an error that serviceWorker cannot be found in the navigator:

    if(&#39;serviceWorker&#39; in navigator) {
        /*
        *
        * Register the Service Worker
        *
        * */
        navigator.serviceWorker.register(&#39;sw.js&#39;).then(function(registration) {
            console.log(&#39;Service Worker Registered&#39;);
        });
    
    } else console.log(&#39;Your browser does not support the Service-Worker!&#39;);

How can I now use the Service Worker again, or how can I get it to run again for all Chrome versions?

Can&#39;t find serviceWorker in navigator anymore

I came across this problem a few times and was wondering if there was a solution to this problem.
My problem occurs on the Chrome mobile app. There, you can scroll down a bit and the address bar disappears. So far, so good, let&#39;s make an example: &lt;br&gt; 
The container&#39;s `height` is set to `100vh`.&lt;br&gt;&lt;br&gt;
[![How it looks with the address bar][1]][1]

As you can see, the bottom part gets cut off.

When I scroll down, it looks like this:&lt;br&gt;&lt;br&gt;
[![enter image description here][2]][2]

Now it looks good. So obviously Chrome calculates the address bar&#39;s height into the viewport height. So my question is: 

Is there a way, that it looks the same with or without the address bar? So that the container expands or something?

  [1]: https://i.stack.imgur.com/Si4wm.jpg
  [2]: https://i.stack.imgur.com/GLjY5.jpg

100vh height when address bar is shown - Chrome Mobile

I am new to flutter, and I want to get Timezone, language, and county Id when I run my project on my device android or iOS. It should detect Timezone, language and country Id from the location of the device. I am newbie to flutter and don&#39;t know how can I get these. 

Can I get these via the internal library?

How to get timezone, Language and County Id in flutter by the location of device in flutter?

When I run a new page, I must specify size of the viewport using the `setViewport` function:

	await page.setViewport({
		width: 1920,
		height: 1080
	})

I want use max viewport.

How can I make the viewport resizable according to the window size?

How to set max viewport in Puppeteer?

I have the following error in the Chrome Dev Tools console on every page-load of my Node/Express/React application:

&gt; Unchecked runtime.lastError: Could not establish connection. Receiving end does not exist

This error makes a reference to localhost/:1. When I hover over this, it shows http://localhost:3000/, the address I&#39;m viewing the app at in the browser.

Anyone have an idea what is going on? Most of the other threads I&#39;ve found that bring up this error seem to be related to someone trying to develop a Chrome Extension, and even then they tend to have very few responses.



How to fix &#39;Unchecked runtime.lastError: Could not establish connection. Receiving end does not exist.&#39;

How these two data amounts, that are located at the bottom of Network Tab differ?

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/U6HcS.png

What is the difference between &quot;transferred&quot; and &quot;resources&quot; in Chrome DevTools Network tab?

Chrome exhibits huge lags when viewing a given web page of mine. I&#39;m using the DevTools *Performance* tab to try and find the culprit which I assume to be somewhere in my JavaScript code.

The following screenshot shows a profile recorded using DevTools. For some of the &quot;tasks&quot; shown in the profile, I can see the details of what the tasks are doing (for example, the one between 8700 ms and 9200 ms is GC), but for other tasks there are no details whatsoever, like the two I have highlighted in the screenshot. How do I figure out what are those tasks doing?

[![Screenshot][1]][1]

  [1]: https://i.stack.imgur.com/JzTfs.png

Content Type	Original Author	Original Content on Stackoverflow
Question	iPzard	View Question on Stackoverflow
Solution 1 - Javascript	fernandopasik	View Answer on Stackoverflow
Solution 2 - Javascript	Dan Dascalescu	View Answer on Stackoverflow

Is there a way to change your timezone in Chrome devtools?

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Solution 2 - Javascript

Does new React Context API trigger re-renders?

Bootstrap 4 multiselect dropdown

Attributions