From [the documentation](https://web.archive.org/web/20120702064328/http://www.jslint.com/lint.html)

&gt; JSLint also recognizes a /*global */ directive that can indicate to JSLint that variables used in this file were defined in other files. The comment can contain a comma separated list of names. Each name can optionally be followed by a colon and either true or false, true indicating that the variable may be assigned to by this file, and false indicating that assignment is not allowed (which is the default). The directive respects function scope.
&gt;
&gt; Some globals can be predefined for you. Select the Assume a browser (browser) option to predefine the standard global properties that are supplied by web browsers, such as document and addEventListener.

Example:

    /*jslint browser: true*/
    /*global $, jQuery*/

As Quentin says, there&#39;s a `/*global*/` directive.

Here is an example (put this at the top of the file):

    /*global var1,var2,var3,var4,var5*/

Make sure the initial global statement is on the same line as `/*`, or else it breaks. 

I am developing an application where I need to update some info every time user logs in to the system, I also use database in the phone. For all those operations (updates, retrieving data from db and etc.) I use async tasks. As up till now I didn&#39;t see why I shouldn&#39;t use them, but recently I experienced that if I do some operations some of my async tasks simply stop on pre-execute and don&#39;t jump to doInBackground. That was just too strange to leave it like that, so I developed another simple application just to check whats wrong. And strange enough, I get the same behavior when count of total async tasks reach 5, the 6th one stops on pre-execute.

Does android have a limit of asyncTasks on Activity/App? Or is it just some bug and it should be reported? Did anyone experience the same problem and maybe found a workaround to it?


Here is the code:

Simply create 5 of those threads to work in a background:

    private class LongAsync extends AsyncTask&lt;String, Void, String&gt;
   	{
   		@Override
   		protected void onPreExecute()
   		{
   			Log.d(&quot;TestBug&quot;,&quot;onPreExecute&quot;);
   			isRunning = true;
   		}

   		@Override
   		protected String doInBackground(String... params)
   		{
   			Log.d(&quot;TestBug&quot;,&quot;doInBackground&quot;);
   			while (isRunning)
   			{
   				
   			}
   			return null;
   		}

   		@Override
   		protected void onPostExecute(String result)
   		{
   			Log.d(&quot;TestBug&quot;,&quot;onPostExecute&quot;);
   		}
   	}

And then create this thread. It will enter preExecute and hang (it will not go to doInBackground).

    private class TestBug extends AsyncTask&lt;String, Void, String&gt;
	{
		@Override
		protected void onPreExecute()
		{
			Log.d(&quot;TestBug&quot;,&quot;onPreExecute&quot;);
			
			waiting = new ProgressDialog(TestActivity.this);
			waiting.setMessage(&quot;Loading data&quot;);
			waiting.setIndeterminate(true);
			waiting.setCancelable(true);
			waiting.show();
		}

		@Override
		protected String doInBackground(String... params)
		{
			Log.d(&quot;TestBug&quot;,&quot;doInBackground&quot;);
			return null;
		}

		@Override
		protected void onPostExecute(String result)
		{
			waiting.cancel();
			Log.d(&quot;TestBug&quot;,&quot;onPostExecute&quot;);
		}
	}

Android AsyncTask threads limits?

Let&#39;s say there are 

    List&lt;string&gt; a1 = new List&lt;string&gt;();
    
    List&lt;string&gt; a2 = new List&lt;string&gt;();

 
Is there way to do like this?

    if (a1 == a2) 
    {
    
    }

How to compare two List&lt;String&gt; to each other?

Hi I have the 3 javascript files.

 * jquery.js
 * utility.js
 * file1.js


In file1.js I have 

    jQuery.noConflict()
    jQuery(document).ready(function($) { 
     // ....
    });


I get an error &#39;jQuery&#39; was used before it was defined. 
and &#39;document&#39; was used before it was defined. 


How do I safely get rid of this warning.  

If I do 

    var document = document || {}; 

then in my utility.js if it is used, it would be null in IE and ok in firefox. 

What is the best solution to this?


JSLint: was used before it was defined

Hi I have the 3 javascript files.
<ul>
<li>jquery.js</li>
<li>utility.js</li>
<li>file1.js</li>
</ul>
In file1.js I have
<pre><code class="hljs language-scss">jQuery.noConflict()
jQuery(document).ready(function($) { 
 // ....
});
</code></pre>
I get an error 'jQuery' was used before it was defined.
and 'document' was used before it was defined.
How do I safely get rid of this warning.
If I do
<pre><code class="hljs language-ini">var document = document || {}; 
</code></pre>
then in my utility.js if it is used, it would be null in IE and ok in firefox.
What is the best solution to this?

I&#39;ve got two collections in my Mongo database, and the `Foo`s contain references to one or more `Bar`s:

    Foo: { 
      prop1: true,
      prop2: true,
      bars: [
         {
         &quot;$ref&quot;: &quot;Bar&quot;,
         &quot;$id&quot;: ObjectId(&quot;blahblahblah&quot;)
         }
      ]
    }

    Bar: {
       testprop: true
    }

What I want is to find all of the `Foo`s that have at least one `Bar` that has its testprop set to true.  I&#39;ve tried this command, but it doesn&#39;t return any results:

    db.Foo.find({ &quot;bars.testprop&quot; : { &quot;$in&quot;: [ true ] } })

Any ideas?

How do I query referenced objects in MongoDB?

When I use XMLHttpRequest, a file is correctly uploaded using [`FormData`][1]. However, when I switch to [`jQuery.ajax`][2], my code breaks.

This is the working original code: 

    function uploadFile(blobFile, fileName) {
        var fd = new FormData();
        fd.append(&quot;fileToUpload&quot;, blobFile);
        var xhr = new XMLHttpRequest();
        xhr.open(&quot;POST&quot;, &quot;upload.php&quot;, true);
        xhr.send(fd);
    }

Here is my unsuccessful `jQuery.ajax` attempt:

    function uploadFile(blobFile, fileName) {
        var fd = new FormData();
        fd.append(&quot;fileToUpload&quot;, blobFile);
        var xm = $.ajax({
            url: &quot;upload.php&quot;,
            type: &quot;POST&quot;,
            data: fd,
        });
    }

What am I doing wrong? How can I get the file to be uploaded correctly, using AJAX?


  [1]: https://developer.mozilla.org/en/XMLHttpRequest/FormData
  [2]: http://api.jquery.com/jQuery.ajax/

How to upload a file using jQuery.ajax and FormData

Can Javascript be called a pure interpreted language? Or does it also have some compiled flavor to it? Could someone guide at the reasons behind both the things whichever being true.

Is Javascript compiled or an interpreted language?

I&#39;ve written a few custom bindings using KnockoutJS. I&#39;m still unsure when to use `ko.utils.unwrapObservable(item)` Looking at the code, that call basically checks to see if `item` is an observable. If it is, return the value(), if it&#39;s not, just return the value. Looking at the section on Knockout about creating custom bindings, they have the following syntax:

    var value = valueAccessor(), allBindings = allBindingsAccessor();
    var valueUnwrapped = ko.utils.unwrapObservable(value);

In this case, they invoke the observable via `()` but then also call `ko.utils.unwrapObservable`. I&#39;m just trying to get a handle on when to use one vs. the other or if I should just always follow the above pattern and use both.

When to use ko.utils.unwrapObservable?

I&#39;m using [KnockoutJS][1] version 2.0.0

If I&#39;m looping through all properties of an object, how can I test whether each property is a `ko.observable`?  Here&#39;s what I&#39;ve tried so far:

        var vm = {
            prop: ko.observable(&#39;&#39;),
            arr: ko.observableArray([]),
            func: ko.computed(function(){
                return this.prop + &quot; computed&quot;;
            }, vm)
        };

        for (var key in vm) {
            console.log(key, 
                vm[key].constructor === ko.observable, 
                vm[key] instanceof ko.observable);
        }

But so far everything is false.


  [1]: http://knockoutjs.com/

Determine if an object property is ko.observable

In javascript to check if a variable was never created, we just do  

    if (typeof MyVariable !== &quot;undefined&quot;){ ... }

I was wonder how I do that in coffeescript?... I try something like

    if (MyVariable?false){ ... }

but this check if `MyVariable` is a function if so that will call MyVariable(false) if not that will call void(0) or something like that.



CoffeeScript Undefined

Things I’ve tried that don’t seem to work:

    if(lastName != &quot;undefined&quot;)

&lt;!-- --&gt;

    if(lastName != undefined)

&lt;!-- --&gt;

    if(undefined != lastName)

How to check if a JavaScript variable is NOT undefined?

&gt; **Possible Duplicate:**  
&gt; [Detecting an undefined object property in JavaScript](https://stackoverflow.com/questions/27509/detecting-an-undefined-object-property-in-javascript)  
&gt; [javascript undefined compare](https://stackoverflow.com/questions/2778901/javascript-undefined-compare)  

&lt;!-- End of automatically inserted text --&gt;

How we can add a check for an undefined variable, like:

    function A(val) {
      if (val == undefined) 
        // do this
      else
        // do this
    }


How to check &#39;undefined&#39; value in jQuery

I&#39;m creating an API that returns results as JSON. Is there a current best practice for whether we should include keys in the result when the value is null?  For example:

&lt;!-- language: lang-js --&gt;

    {
        &quot;title&quot;:&quot;Foo Bar&quot;,
        &quot;author&quot;:&quot;Joe Blow&quot;,
        &quot;isbn&quot;:null
    }

or

&lt;!-- language: lang-js --&gt;

    {
        &quot;title&quot;:&quot;Foo Bar&quot;,
        &quot;author&quot;:&quot;Joe Blow&quot;
    }

Since the second is smaller I am leaning towards this style, but I&#39;m not sure if there is a preferred style or not. From a client perspective it seems like both styles would be functionally equivalent. Any pros or cons to each?


Should JSON include null values

In my HTML5 page, I have a div with `mousemove` event as follows:

	$(&#39;#canvas&#39;).mousemove(function(e){
		xpos = e.offsetX;
		ypos = e.offsetY;
		$(&#39;#mouse&#39;).html(&quot;X : &quot; + xpos + &quot; ; Y : &quot; + ypos);
	});

It works fine with Google Chrome. But in Firefox, both the are giving the value `undefined`. I have checked it by using Firebug, that is, logged the `e` object to console. Both `offsetX` and `offsetY` are found to be `undefined`.

When I searched in Google, there was a solution saying I should use `layerX` and `layerY`, if both `offsetX` and `offsetY` are undefined.
But from Firebug, I was not able to find it. And even I had given it a try like this:

    xpos = (e.offsetX==undefined)?e.layerX:e.offsetX;
    ypos = (e.offsetY==undefined)?e.layerY:e.offsetY;

But that&#39;s also giving `undefined` as values.

I am using the most recent jQuery - v1.8.2. And I am testing in my Firefox v14.0.1

Any ideas or suggestions?

---
**EDIT**

Thanks to dystroy and vusan for helping me. The solution to the above issue is as follows:

**SOLUTION**

    $(&#39;#canvas&#39;).mousemove(function(e){
      $(&#39;#cursor&#39;).show();
      if(e.offsetX==undefined) // this works for Firefox
      {
        xpos = e.pageX-$(&#39;#canvas&#39;).offset().left;
        ypos = e.pageY-$(&#39;#canvas&#39;).offset().top;
      }				
      else                     // works in Google Chrome
      {
        xpos = e.offsetX;
        ypos = e.offsetY;
      }
      $(&#39;#mouse&#39;).html(&quot;X : &quot; + xpos + &quot; ; Y : &quot; + ypos);
    });


HTML5 with jQuery - e.offsetX is undefined in Firefox

What would be the correct way to solve the jslint error in this case? I&#39;m adding a getter function to an object which uses this. I don&#39;t know how to do this without creating the function inside the loop.

    for (var i = 0; i&lt;processorList.length; ++i) {
       result[i] = {
           processor_: timestampsToDateTime(processorList[i]),
           name_: processorList[i].processorName,
           getLabel: function() { // TODO solve function in loop.
                return this.name_;
           }
       };
    }


Don&#39;t make functions within a loop

Consider the following code:

	for (var i=0; i&lt;100; i++) {
		// your code here
	}
	// some other code here
	for (var i=0; i&lt;500; i++) {
		// custom code here
	}

Any decent lint tool (jslint, jshint or built in IDE) will tell warning - `duplicate declaration of variable i`. This can be solved by using variable with another name (`k`, `j`) or moving declaration to the top:

	var i; // iterator
	for (i=0; i&lt;100; i++) {}
	for (i=0; i&lt;500; i++) {}

I am not fond of both variants - I don&#39;t make declarations at the top usually (and even if I did I wouldn&#39;t want see there helper variables - `i`, `j`, `k`) and really nothing bad is going on in those examples to change variables&#39; names for.

Though I do want a huge warning in case I write something like this:

	for (var i=0; i&lt;100; i++) {
		for (var i=0; i&lt;500; i++) {} // now that&#39;s bad
	}

What&#39;s your approach to such cases?

Dealing with duplicate declaration warning for loop variables

JSLint is not passing this as a valid code:

    /* global someVar: false */
    if (typeof someVar === &quot;undefined&quot;) {
        var someVar = &quot;hi!&quot;;
    }

What is the correct way?

What is the correct way to check if a global variable exists?

&gt; **Possible Duplicate:**  
&gt; [JSLint: was used before it was defined](https://stackoverflow.com/questions/9621162/jslint-was-used-before-it-was-defined)  

&lt;!-- End of automatically inserted text --&gt;

I run `JSlint` and saw errors like that:

&lt;pre&gt;&#39;foo&#39; is not defined.
var x = foo();&lt;/pre&gt;

`foo` is a function defined in another `JavaScript` file `foo.js`. As I understand there is no &quot;import / require&quot; directives in `JavaScript` to reference the `foo` function defined in another source file.

How can I fix this error repoted by `JSlint`? 


How to fix &quot;foo is not defined&quot; error reported by JSlint?

I have a very long regular expression, which I wish to split into multiple lines in my JavaScript code to keep each line length 80 characters according to JSLint rules. It&#39;s just better for reading, I think.
Here&#39;s pattern sample:

    var pattern = /^(([^&lt;&gt;()[\]\\.,;:\s@\&quot;]+(\.[^&lt;&gt;()[\]\\.,;:\s@\&quot;]+)*)|(\&quot;.+\&quot;))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;

Content Type	Original Author	Original Content on Stackoverflow
Question	Chun ping Wang	View Question on Stackoverflow
Solution 1 - Javascript	Quentin	View Answer on Stackoverflow
Solution 2 - Javascript	stanton	View Answer on Stackoverflow

JSLint: was used before it was defined

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Solution 2 - Javascript

How to compare two List<String> to each other?

Android AsyncTask threads limits?

Attributions