Yes. You can prefix every expressions with `::`, even the ones in `ngIf` or `ngClass`:

    &lt;div ng-if=&quot;::(user.isSomething &amp;&amp; user.isSomethingElse)&quot;&gt;&lt;/div&gt;
    &lt;div ng-class=&quot;::{classNameFoo: user.isSomething}&quot;&gt;&lt;/div&gt;

Actually, [the code][1] simply checks that the two first characters in the expression are `:` in order to activate the one-time binding (and then removes them, thus the parenthesis aren&#39;t even needed). Everything else remains the same.

  [1]: https://github.com/angular/angular.js/blob/cee429f0aaebf32ef1c9aedd8447a48f163dd0a4/src/ng/parse.js#L1027

I begin my project with a split view controller as initial view controller and start it automatically from storyboard.

Generally, an app with this UI have **one and only one** split view controller as root, so I create a **static variable** in the subclass and set it when initialisation was done.

So I want try this behaviour with swift.

I read the Swift programming language guide book on iBook about Type properties (with static and class keyword) and trying a piece of code to the job: 

    import UIKit

    class SplitViewController: UISplitViewController {
        
        class func sharedInstance() -&gt; SplitViewController {
            return SplitViewController.instance
        }
        
        class let instance: SplitViewController = nil
        
        init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
            super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
            self.initialization()
        }
    
        init(coder aDecoder: NSCoder!) {
            super.init(coder: aDecoder);
            self.initialization()
        }
        
        func initialization() {
            SplitViewController.instance = self;
        }
    }

but I figured out when Xcode say the class keyword for type properties wasn&#39;t supported yet.

 ![error detail in image][1]

**Did you have a solution to do this ?**


  [1]: http://i.stack.imgur.com/nIfLo.png


Class variables not yet supported

I recently changed from `Spyder` to `PyCharm` as a Python IDE. In `Spyder` I have often used the variable explorer feature (see picture). Is this feature also available in `PyCharm`?![enter image description here][1]


  [1]: http://i.stack.imgur.com/DH9gy.png

I found this [here](http://confluence.jetbrains.com/display/PYH/PyCharm+3.0+Roadmap), that &quot;`Variable explorer in Python console (traff)`&quot; should be included in `PyCharm 3`, but I cannot find that. Maybe someone could tell me how to use that tool.

Is there a Variable Explorer for PyCharm

AngularJS has a new feature since the version 1.3.0-beta.10: the [&quot;lazy one-time binding&quot;][1].

Simple expressions can be prefixed with `::`, telling angular to stop watching after the expression was first evaluated. The common example given is something like:

    &lt;div&gt;{{::user.name}}&lt;/div&gt;

Is there a similar syntax for expressions like the following ones?

    &lt;div ng-if=&quot;user.isSomething &amp;&amp; user.isSomethingElse&quot;&gt;&lt;/div&gt;
    &lt;div ng-class=&quot;{classNameFoo: user.isSomething}&quot;&gt;&lt;/div&gt;

  [1]: https://github.com/angular/angular.js/commit/cee429f0aaebf32ef1c9aedd8447a48f163dd0a4

Angular lazy one-time binding for expressions

AngularJS has a new feature since the version 1.3.0-beta.10: the <a href="https://github.com/angular/angular.js/commit/cee429f0aaebf32ef1c9aedd8447a48f163dd0a4" target="_blank" rel="noopener noreferrer">"lazy one-time binding"</a>.
Simple expressions can be prefixed with <code>::</code>, telling angular to stop watching after the expression was first evaluated. The common example given is something like:
<pre><code class="hljs language-css">&#x3C;div>{{::user.name}}&#x3C;/div>
</code></pre>
Is there a similar syntax for expressions like the following ones?
<pre><code class="hljs language-ini">&#x3C;div ng-if="user.isSomething &#x26;&#x26; user.isSomethingElse">&#x3C;/div>
&#x3C;div ng-class="{classNameFoo: user.isSomething}">&#x3C;/div>
</code></pre>

I have a JavaScript code which save string to the Local storage, the string size is 400000,

    var dataURL = canvas.toDataURL(&quot;image/jpg&quot;).toString();
    localStorage.setItem(&quot;dataURL&quot;, dataURL);

I open the html file from chrome, in one computer its OK in the other computer i get 

&gt; Uncaught QuotaExceededError: Failed to execute &#39;setItem&#39; on
&gt; &#39;Storage&#39;: Setting the value of &#39;dataURL&#39; exceeded the quota.

In this computer I allowed to save string length no more than 100000 chars.
Both computers have the same chrome&#39;s Version 35.0.1916.114 m 
Why?

Setting the value of &#39;dataURL&#39; exceeded the quota

I want to implement a simple file upload in my intranet-page, with the smallest setup possible.

This is my HTML part:

    &lt;input id=&quot;sortpicture&quot; type=&quot;file&quot; name=&quot;sortpic&quot; /&gt;
    &lt;button id=&quot;upload&quot;&gt;Upload&lt;/button&gt;

and this is my JS jquery script:

    $(&quot;#upload&quot;).on(&quot;click&quot;, function() {
        var file_data = $(&quot;#sortpicture&quot;).prop(&quot;files&quot;)[0];   
        var form_data = new FormData();
        form_data.append(&quot;file&quot;, file_data);
        alert(form_data);
        $.ajax({
            url: &quot;/uploads&quot;,
            dataType: &#39;script&#39;,
            cache: false,
            contentType: false,
            processData: false,
            data: form_data,                         
            type: &#39;post&#39;,
            success: function(){
            	alert(&quot;works&quot;); 
            }
        });
    });


There is a folder named &quot;uploads&quot; in the root directory of the website, with change permissions for &quot;users&quot; and &quot;IIS_users&quot;.

When I select a file with the file-form and press the upload button, the first alert returns &quot;[object FormData]&quot;. the second alert doesn&#39;t get called and the&quot;uploads&quot; folder is empty too!?

Can someone help my finding out whats wrong?

Also the next step should be, to rename the file with a server side generated name. Maybe someone can give me a solution for this, too.

jQuery AJAX file upload PHP

I am interested in the &quot;debouncing&quot; function in javascript, written here : http://davidwalsh.name/javascript-debounce-function


Unfortunately the code is not explained clearly enough for me to understand.  Can anyone help me figure out how it works (I left my comments below). In short I just really do not understand how this works

       // Returns a function, that, as long as it continues to be invoked, will not
       // be triggered. The function will be called after it stops being called for
       // N milliseconds.


    function debounce(func, wait, immediate) {
    	var timeout;
    	return function() {
    		var context = this, args = arguments;
    		var later = function() {
    			timeout = null;
    			if (!immediate) func.apply(context, args);
    		};
    		var callNow = immediate &amp;&amp; !timeout;
    		clearTimeout(timeout);
    		timeout = setTimeout(later, wait);
    		if (callNow) func.apply(context, args);
    	};
    };

EDIT: The copied code snippet previously had `callNow` in the wrong spot.

Can someone explain the &quot;debounce&quot; function in Javascript

Why can&#39;t you open the link in the following demo:  
http://html5-demos.appspot.com/static/a.download.html  

You cannot even right click and open it in a new tab/window. Is there any setting in the browser I need to customize?

Open links made by createObjectURL in IE11

I have a simple form. All of the components and state are held in the Page component. There are 2 display headers and 3 input fields. The first input is supposed to be text, and the second and third are supposed to be ints. When the user inputs the wrong type of data, I want to have an error message pop up next to the input field. My questions relate to best practices in React.JS

Who decides that the value is in valid? I suppose that the only job of the input field is to direct the value back to component holding the state, so does this mean that only Page can determine if a value is valid?

How should I then have the pop up appear? Should Page have to trigger a new boolean state element that will be passed through perp that will tell Adaptive_Input to reveal the error message?

[JSFiddle][1]

**JS:**

    /**
     * @jsx React.DOM
     */
    var Adaptive_Input = React.createClass({ 
    	handle_change: function(){
    		var new_text = this.refs.input.getDOMNode().value;
    		this.props.on_Input_Change(new_text);
    	},
    	render: function(){
    		return (
    				&lt;div className=&#39;adaptive_placeholder_input_container&#39;&gt;
    					&lt;input 
    						className=&quot;adaptive_input&quot;
    						type=&quot;text&quot; 
    						required=&quot;required&quot; 
    						onChange= {this.handle_change}
    						ref=&quot;input&quot;
    					&gt;&lt;/input&gt;
    					&lt;label
    						className=&quot;adaptive_placeholder&quot;
    						alt={this.props.initial}
    						placeholder={this.props.focused}
    					&gt;&lt;/label&gt;
    				&lt;/div&gt;    			
    				);
    	}
    });
    
    var Form = React.createClass({
    	render: function(){
    		return (
    				&lt;form&gt;
    					&lt;Adaptive_Input
    						initial={&#39;Name Input&#39;}
    						focused={&#39;Name Input&#39;}
    						on_Input_Change={this.props.handle_text_input}
    					/&gt;
    					&lt;Adaptive_Input
    						initial={&#39;Value 1&#39;}
    						focused={&#39;Value 1&#39;}
    						on_Input_Change={this.props.handle_value_1_input}
    					/&gt;
    					&lt;Adaptive_Input
    						initial={&#39;Value 2&#39;}
    						focused={&#39;Value 2&#39;}
    						on_Input_Change={this.props.handle_value_2_input}
    					/&gt;
    				&lt;/form&gt;
    				);
    	}
    });
    
    var Page = React.createClass({
    	getInitialState: function(){
    		return {
    			Name : &quot;No Name&quot;,
    			Value_1 : &#39;0&#39;,
    			Value_2 : &#39;0&#39;,
    			Display_Value: &#39;0&#39;
    		};
    	},
    	handle_text_input: function(new_text){
    		this.setState({
    				Name: new_text
    			});
    	},
    	handle_value_1_input: function(new_value){
    		console.log(&quot;===&quot;);
    		var updated_display = parseInt(new_value) + parseInt(this.state.Value_2);
    		updated_display = updated_display.toString();
    		this.setState({
    				Display_Value: updated_display 
    			});
    	},
    	handle_value_2_input: function(new_value){
    		var updated_display = parseInt(this.state.Value_1) + parseInt(new_value);
    		updated_display = updated_display.toString();
    		this.setState({
    				Display_Value: updated_display
    			});
    	},
    	render: function(){
    		return(
    				&lt;div&gt;
    					&lt;h2&gt;{this.state.Name}&lt;/h2&gt;
    					&lt;h2&gt;Value 1 + Value 2 = {this.state.Display_Value}&lt;/h2&gt;
    					&lt;Form
    						handle_text_input={this.handle_text_input}
    						handle_value_1_input = {this.handle_value_1_input}
    						handle_value_2_input = {this.handle_value_2_input}
    					/&gt;
    				&lt;/div&gt;
    		);
    	}
    });
    
    React.renderComponent(&lt;Page /&gt;, document.body);


  [1]: http://jsfiddle.net/easilyBaffled/bgC6E/1/

How to properly validate input values with React.JS?

How to subscribe on property change when using `controller as` syntax?

&lt;!-- language: lang-js --&gt;

    controller(&#39;TestCtrl&#39;, function ($scope) {
      this.name = &#39;Max&#39;;
      this.changeName = function () {
        this.name = new Date();
      }
      // not working       
      $scope.$watch(&quot;name&quot;,function(value){
        console.log(value)
      });
    });

&lt;!-- language: lang-html --&gt;

    &lt;div ng-controller=&quot;TestCtrl as test&quot;&gt;
      &lt;input type=&quot;text&quot; ng-model=&quot;test.name&quot; /&gt;
      &lt;a ng-click=&quot;test.changeName()&quot; href=&quot;#&quot;&gt;Change Name&lt;/a&gt;
    &lt;/div&gt;  


  


Angularjs: &#39;controller as syntax&#39; and $watch

In my Angular JS project, I&#39;ve an `&lt;a&gt;` anchor tag, which when clicked makes an HTTP `GET` request to a WebAPI method that returns a file. 

Now, I want the file to be downloaded to the user once the request is successful. How do I do that?

The anchor tag: 

&lt;!-- language: html --&gt;

    &lt;a href=&quot;#&quot; ng-click=&quot;getthefile()&quot;&gt;Download img&lt;/a&gt;

AngularJS:

&lt;!-- language: javascript --&gt;

    $scope.getthefile = function () {        
        $http({
            method: &#39;GET&#39;,
            cache: false,
            url: $scope.appPath + &#39;CourseRegConfirm/getfile&#39;,            
            headers: {
                &#39;Content-Type&#39;: &#39;application/json; charset=utf-8&#39;
            }
        }).success(function (data, status) {
            console.log(data); // Displays text data if the file is a text file, binary if it&#39;s an image            
            // What should I write here to download the file I receive from the WebAPI method?
        }).error(function (data, status) {
            // ...
        });
    }

My WebAPI method:

&lt;!-- language: c# --&gt;

    [Authorize]
    [Route(&quot;getfile&quot;)]
    public HttpResponseMessage GetTestFile()
    {
    	HttpResponseMessage result = null;
    	var localFilePath = HttpContext.Current.Server.MapPath(&quot;~/timetable.jpg&quot;);
    
    	if (!File.Exists(localFilePath))
    	{
    		result = Request.CreateResponse(HttpStatusCode.Gone);
    	}
    	else
    	{
            // Serve the file to the client
    		result = Request.CreateResponse(HttpStatusCode.OK);
    		result.Content = new StreamContent(new FileStream(localFilePath, FileMode.Open, FileAccess.Read));
    		result.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue(&quot;attachment&quot;);
    		result.Content.Headers.ContentDisposition.FileName = &quot;SampleImg&quot;;                
    	}
    
    	return result;
    }

Download file from an ASP.NET Web API method using AngularJS

I am using `&lt;input type=&quot;file&quot;&gt;` to upload *audio* files.

To do that I am using `accept=&quot;audio/*&quot;`.  Because of this, the browser&#39;s file-select dialog shows only audio files by default.  However, there is an option called &quot;All Files&quot; in that dialog box that I don&#39;t want.

(note - Any solution in Javascript , jQuery and AngularJs is also welcome)

![enter image description here][1]

How can I disable/remove the &quot;All Files&quot; option?


  [1]: http://i.stack.imgur.com/tmIJX.png

Remove &#39;All Files&#39; option from HTML file input

    XMLHttpRequest cannot load http://mywebservice. No &#39;Access-Control-Allow-Origin&#39; header is present on the requested resource. Origin &#39;http://localhost:9000&#39; is therefore not allowed access.

I get this error when I try to run my web-service from inside my code. I tried finding about it and tried many solutions which were suggested which I found on net. Pasting the code below.

    &lt;form name=&quot;LoginForm&quot; ng-controller=&quot;LoginCtrl&quot; ng-submit=&quot;init(username,password,country)&quot;&gt;
        &lt;label&gt;Country&lt;/label&gt;&lt;input type=&quot;text&quot; ng-model=&quot;country&quot;/&gt;&lt;br/&gt;&lt;br/&gt;
		&lt;label&gt;UserName&lt;/label&gt;&lt;input type=&quot;text&quot; ng-model=&quot;username&quot; /&gt;&lt;/br&gt;&lt;/br&gt;
		&lt;label&gt;Password&lt;/label&gt;&lt;input type=&quot;password&quot; ng-model=&quot;password&quot;&gt;
		&lt;/br&gt;
		&lt;button type=&quot;submit&quot; &gt;Login&lt;/button&gt;
	&lt;/form&gt;

And controller form the corresponding js is: 

    app.controller(&#39;LoginController&#39;, [&#39;$http&#39;, &#39;$scope&#39;, function ($scope, $http) {
		$scope.login = function (credentials) {
		$http.get(&#39;http://mywebservice&#39;).success(function ( data ) {
			alert(data);
			});
		}
	}]);

The web-service works fine when I hit it from URL bar. How to resolve the problem? Kindly help!

 

 

No &#39;Access-Control-Allow-Origin&#39; header is present on the requested resource- AngularJS

I do not quite understand when to use a directive and when it would be more appropriate to use nginclude. Take this example: I have a partial, `password-and-confirm-input-fields.html`, that is the html for entering and confirming a password. I use this both under signup-page and under change-password-page. Those two pages has a controller each, the partial html has no dedicated controller.

Should I use directive or `ngInclude` for this?

AngularJS: ngInclude vs directive

I want to make navigation from child components that render inside router-outlet.
My parent component have a router config and I want to navigate manually on some event. But I don&#39;t know how I can pass from child to parent some data (for navigation) without  output. Because this construction is non working

     &lt;router-outlet (navigateTo)=&quot;navigateToMessagePart($event)&quot;&gt;&lt;/router-outlet&gt;

How I can do it in right way? Maybe navigate it from child? But how I can get parent methods from child.
Many thanks for any help!

Angular 2 output from router-outlet

The desired behaviour is to pass an argument (text) to the onClick handler to console.log it but it seems that I&#39;m doing something wrong with the syntax.

If I leave the argument out as below, it&#39;s working fine:

    export default class Nav extends Component {
      componentDidMount() {
        this.props.pickNumber(3);
      }
    
      onPress() {
        console.log(&#39;FOOOBAAR&#39;);
      }
      render() {
        return (
          &lt;View&gt;
            &lt;Text&gt;####################&lt;/Text&gt;
            &lt;Text&gt;Intro Screen&lt;/Text&gt;
            &lt;Text&gt;Number: {this.props.numbers}&lt;/Text&gt;
            &lt;TouchableHighlight onPress={this.onPress.bind(this)}&gt;
              &lt;Text&gt;Go to Foo&lt;/Text&gt;
            &lt;/TouchableHighlight&gt;
          &lt;/View&gt;
        );
      }
    
    }

However, if I want to pass an argument to the onPress handler, it complains &#39;Cannot read property &#39;bind&#39; of undefined.


    export default class Nav extends Component {
      componentDidMount() {
        this.props.pickNumber(3);
      }
    
      onPress(txt) {
        console.log(txt);
      }
      render() {
        return (
          &lt;View&gt;
            &lt;Text&gt;####################&lt;/Text&gt;
            &lt;Text&gt;Intro Screen&lt;/Text&gt;
            &lt;Text&gt;Number: {this.props.numbers}&lt;/Text&gt;
            &lt;TouchableHighlight onPress={this.onPress(&#39;foo&#39;).bind(this)}&gt;
              &lt;Text&gt;Go to Foo&lt;/Text&gt;
            &lt;/TouchableHighlight&gt;
          &lt;/View&gt;
        );
      }
    
    }

Thanks

Addition: 
If I change it to:

    onPress={this.onPress.bind(&#39;foo&#39;)}

it does not work either.


react-native onPress binding with an argument

While adding a single class works great in this way - 

`[class.loading-state]=&quot;loading&quot;`

But how do I add multiple classes
Ex if `loading` is `true` add class - `&quot;loading-state&quot; &amp; &quot;my-class&quot;` 

How do I get it done via the `[class] binding`

Angular 2 add multiple classes via [class.className] binding

I want to parameterise the following computation using `dplyr` that finds which values of `Sepal.Length` are associated with more than one value of `Sepal.Width`:

    library(dplyr)

    iris %&gt;%
        group_by(Sepal.Length) %&gt;%
        summarise(n.uniq=n_distinct(Sepal.Width)) %&gt;%
        filter(n.uniq &gt; 1)

Normally I would write something like this:

    not.uniq.per.group &lt;- function(data, group.var, uniq.var) {
        iris %&gt;%
            group_by(group.var) %&gt;%
            summarise(n.uniq=n_distinct(uniq.var)) %&gt;%
            filter(n.uniq &gt; 1)
    }

However, this approach throws errors because `dplyr` uses [non-standard evaluation](http://adv-r.had.co.nz/Computing-on-the-language.html). How should this function be written?

Pass arguments to dplyr functions

In the namespace `MS.Internal`, there is a class named `NamedObject`.

It has a weird block of code:

    public override string ToString()
    {
      if (_name[0] != &#39;{&#39;)
      {
        // lazily add {} around the name, to avoid allocating a string 
        // until it&#39;s actually needed
        _name = String.Format(CultureInfo.InvariantCulture, &quot;{{{0}}}&quot;, _name);
      }

      return _name;
    }

I&#39;m curious about this comment specifically:

        // lazily add {} around the name, to avoid allocating a string 
        // until it&#39;s actually needed
        _name = String.Format(CultureInfo.InvariantCulture, &quot;{{{0}}}&quot;, _name);

How is that &#39;lazy&#39;? What does it do to be lazy?

__________ 

Full class from the [reference source][1]:


    //---------------------------------------------------------------------------- 
    //
    // &lt;copyright file=&quot;NamedObject.cs&quot; company=&quot;Microsoft&quot;&gt;
    //    Copyright (C) Microsoft Corporation.  All rights reserved.
    // &lt;/copyright&gt; 
    //
    // Description: Placeholder object, with a name that appears in the debugger 
    // 
    //---------------------------------------------------------------------------
    
    using System;
    using System.Globalization;
    using MS.Internal.WindowsBase;
    
    namespace MS.Internal
    {
      /// &lt;summary&gt; 
      /// An instance of this class can be used wherever you might otherwise use
      /// &quot;new Object()&quot;.  The name will show up in the debugger, instead of 
      /// merely &quot;{object}&quot;
      /// &lt;/summary&gt;
      [FriendAccessAllowed]   // Built into Base, also used by Framework.
      internal class NamedObject
      {
        public NamedObject(string name)
        {
          if (String.IsNullOrEmpty(name))
            throw new ArgumentNullException(name);
    
          _name = name;
        }
    
        public override string ToString()
        {
          if (_name[0] != &#39;{&#39;)
          {
            // lazily add {} around the name, to avoid allocating a string 
            // until it&#39;s actually needed
            _name = String.Format(CultureInfo.InvariantCulture, &quot;{{{0}}}&quot;, _name);
          }
    
          return _name;
        }
    
        string _name;
      }
    }
    
    // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
    // Copyright (c) Microsoft Corporation. All rights reserved.


  [1]: http://referencesource.microsoft.com/#WindowsBase/Base/MS/Internal/NamedObject.cs,6a3daa330bc0a54b

What does {{{0}}} on string.Format do?

    [1, 2, 3, -1, -2].filter({ $0 &gt; 0 }).count // =&gt; 3
    
    [1, 2, 3, -1, -2].lazy.filter({ $0 &gt; 0 }).count // =&gt; 3

What is the advantage of adding `lazy` to the second statement. As per my understanding, when `lazy` variable is used, memory is initialized to that variable at the time when it used. How does it make sense in this context?

[![enter image description here][1]][1]

Trying to understand the the use of `LazySequence` in little more detail. I had used the `map`, `reduce` and `filter` functions on sequences, but never on `lazy` sequence. Need to understand why to use this?

  [1]: https://i.stack.imgur.com/kx3L9.png

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

Angular lazy one-time binding for expressions

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Is there a Variable Explorer for PyCharm

Class variables not yet supported

Attributions