Chofoteddy's questions

Rust has a feature that allows you to branch the way you compare objects through the and traits .PartialEqEq

Deducing from the documentation, the only difference between the two would be that it Eqadds the reflexive property to the formula.

But then, are there cases of objects that implement PartialEqwith custom code and that require Eq?

That is, if creating my own implementation of PartialEqto compare both objects, in what case would it be advisable and even mandatory to use Eq?

#[derive(PartialEq, Eq)]
enum Color {
    Red,
    Blue,
}

#[derive(PartialEq, Eq)]
enum Category {
    Hatchback,
    Truck,
}

struct Car {
    color: Color,
    category: Category,
}

impl PartialEq for Car {
    fn eq(&self, other: &Self) -> bool {
        self.category == other.category
    }
}


fn main() {
    let my_hatch = Car {
        color: Color::Blue,
        category: Category::Hatchback,
    };
    
    let my_truck = Car {
        color: Color::Red,
        category: Category::Truck,
    };
    
    println!("Are those two cars equals? {}", my_hatch == my_truck);
}

Personally I like to use double quotes on HTML attributes/values, but I have seen codes where the use of single quotes is what predominates over the document and even! some without quotation marks.

<input type="text" name="age" />
<input type='text' name='age' />
<input type=text name=age />

Apart from knowing the compatibility of its use with browsers, I would like to know which of these forms to use and why? are there any functional implications that affect performance?

Example:

In many programming languages; The difference between single and double quotes to declare text strings is the interpolation, but it is unnecessary to discuss that about HTML since we know it does not fall into that category. But is there any behavior that alters the way the data is presented?

I am working on a fairly simple evaluation system, but the point is that on the same screen a user can add dynamic elements and later fill in information.

The problem is that if a user (whether by mistake or for another reason) wants to refresh or close the tab, they are alerted about the pending changes or about the loss of their progress; Kind of like Facebook does when you leave a post halfway through and want to exit the tab.

What is the event that is triggered? or what function should be registered for it?

// Se ejecuta si el usuario trata de salir con cambios pendientes.
document.addEventListener('leave', fn (evt) {});

I imagine that in a way I also need to notify the browser that there are "things" pending, correct?

I am trying to get the execution time of an operation that runs iteratively, but when trying to compare, I get 0 seconds.

$startedAt = time();
for ($i = 0; $i < 10000; $i++) {
    // Solo como código demostrativo.
    preg_match('/^0{3}\b/', $number);
}
$finishedAt = time();

echo 'Tiempo: ' . ($finishedAt - $startedAt);

Searching in php.net I don't find an alternative function, is there another solution?

I had been programming in JavaScript for some time and I had never noticed that peculiarity that it has with the value NaN.

I decided to investigate and the most I found was: NaN - JavaScript | MDN / [English] .

I understood that it NaNis the reference of “Not a Number” (it is not a number) but I am not clear why a NaN is not equal to another NaN using the operator ==, ===.

parseFloat('NaN') == parseFloat('NaN'); // false
parseFloat('NaN') == NaN; // false
NaN == NaN; // false

What happens at the logical level that equality is not fulfilled? Why does it not also apply to the expression undefined == undefined?

I am in the problem that I need to export a DB but I would like to learn how to export it and encrypt it with GPG (using symmetric encryption). My command looks something like the following:

$ mysqldump -u user_db -p name_db | gpg -a --cipher-algo AES -o name_db.sql.gpg

But when I run it, my terminal goes into standby mode and I can't even Ctrl + Cfinish the process. I closed terminal and when I tried again, just after putting the MySQL password, I got:

gpg: no valid OpenPGP data found.
gpg: processing message failed: Unknown system error

I understand that the pipe symbol "|" it grabs the printed content of command1 so that command2 can grab it, but I can't get it to work.

$ comando1 | comando2

Note: I don't want to save the file .sqland then encrypt it, rather I want to do it on top of the same command.

I am not an expert in English, but reading about ES6 I have come across on several occasions that they mention Array-like objects (especially when I read about Map , Set , WeakMap , WeakSet ), as in the following context:

Other collections support for-of too

for–ofis not just for arrays. It also works on most array-like objects, like DOM NodeLists.

From what little I understand, it looks something like what jQuery returns when they query a list of elements with (example) $('a').

I understand that an Array is already an object, but what does the term Array-like object refer to ? How do I create one? What is the purpose compared to an array?

I have a cronjob configured as follows:

0 * * * * php ~/ruta/archivo.php >> ~/log.txt

After performing archivo.phpa data synchronization, it returns two possible responses:

• The database was successfully updated
• The database is up to date

That saves it perfectly in the log.txtbut when I want to add the date of the command to the cron:

date +'%Y-%m-%d %T' // 2016-01-12 21:59:06

According to me, I would get something like the following:

0 * * * * php ~/ruta/archivo.php $(date +'%Y-%m-%d %T') >> ~/log.txt

But when I see the log, it doesn't save any data from the command date, it shows me the impressions like the following:

La base de datos está actualizada
La base de datos está actualizada
La base de datos está actualizada
La base de datos se actualizó correctamente
La base de datos está actualizada
La base de datos está actualizada
...

Instead if I execute the following if it works as I expect:

echo 'Soy un texto: ' $(date +'%Y-%m-%d %T') >> ~/log.txt

The text in the log remains:

...
Soy un texto: 2016-01-12 21:59:06

Reading the MDN documentation where the primitive data is talked about, no matter Symbolhow much I read and reread, I don't understand what would be a use case for said element other than to iterate Symbol.iterator.

The documentation says that its use is for debugging purposes , but even with that I don't understand why use a to debug if or Symbolexists .console.log()debugger

I understand that it is a primitive data and therefore immutable. In the examples I have seen that they do something like the following:

var sym = Symbol('Llave'),
    obj = {
        [sym]: 'valor'
    };

console.log(obj[sym]); // valor
console.log(obj['Llave']); // undefined

Why use a Symbol? if a traditional key (key: value) can be used.

Sources:

• Symbol-JavaScript | mdn
• lukehoban/es6features GitHub
• ECMAScript 6 — New Features: Overview & Comparison

I have seen sites like Twitter, Facebook, Bitbucket, Github, Gmail, among others. They add emojisafter typing a certain set of characters or some add them after posting the content. Something like:

:D - -> ?

I imagine there is a listener, programmed with regular expressions JavaScriptwaiting for content that matches that pattern and then replacing it with images or unicode (such as Font Awesome).

I would like to know what happens to achieve that. Is there a design pattern I can use? Do I need to have any special configuration in my DB( MySQL)?

Note: More than using a framework (if it exists) I would like to know how it is achieved.

I am interested in knowing the difference between these to know when to use which one? In the case that I need to modify the permissions of a directory or file on my localhost .

Note: I have read several topics in Spanish but I perceive that they explain in a banal way, I find better information in English but I do not fully understand them.

In the end I end up solving it with something that I consider "nacade" but it works:

$ sudo chmod 777 -R /ruta/

Although after time I have already tired of this solution and I prefer to do it correctly.

It turns out that following the documentation of the fancybox library, I find that to define the behavior of its elements through classes, a syntax like the following must be followed:

<a href="http://www.dominio-ejemplo.mx/pagina" class="fancybox.iframe">
    <!-- Código HTML -->
</a>

I want to add " x " behaviors via jQuery to such elements, but I find myself still escaping the "." (dot) with the backslash () does not take the element.

I leave the following snippet:

$(function(){
  $('button').on('click', function(){
    /* No funciona */
    $('.fancybox\.image').remove();
  });
});

.fancybox\.iframe {
  color: white;
  background-color: red;
}

.fancybox\.image {
  color: white;
  background-color: green;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<ul>
  <li>
    <a href="http://www.dominio-ejemplo.mx/pagina" class="fancybox.iframe">Estilo iframe</a>
  </li>
  <li>
    <a href="http://www.dominio-ejemplo.mx/pagina" class="fancybox.image">Estilo imagen</a>
  </li>
</ul>

<button>Borrar: fancybox.iframe</button>

I have an application in which I would like to show the name of the town or city where the location of the person using the application is, currently I have the LATITUDE and LONGITUDE . But now I don't know how to proceed.

navigator.geolocation.getCurrentPosition(function(pos) {
    var position = new google.maps.LatLng(pos.coords.latitude, pos.coords.longitude);
}, function (error) {
    // Código de error
});

I am working on a project and I use git for version management. The problem I have is that if I change the permissions of the directory, they appear to me that the files were modified, but when I use git diffto observe the changes, a list like the following appears:

diff --git a/assets/images/icon-32-bcache.png b/assets/images/icon-32-bcache.png
old mode 100644
new mode 100755
diff --git a/assets/images/icon-32-help.png b/assets/images/icon-32-help.png
old mode 100644
new mode 100755

I consider these changes garbage to be in a commit. Is there a command that ignores these changes?

I need to search for all the files that have a hyphen followed by the number 2015 in a maximum depth of 1 directory, this would be equivalent to the current directory and another within a folder without going to its sub-folders. Taking into account that I have a structure like the following:

./
- index-2015/
-- otrodir/
-- assets-2015/
-- tmp/ 
- contacto-2015/
- contacto/
- index/
- subdominios/
-- subd1/ <-- A partir de aquí ya no debería listar las coincidencias
--- hoja1-2015/
--- hoja2-2015/

command in use

To list all directories of the current level I'm on (with no matching sub-directories) I use:

ls | grep '\w-2015'

The problem with that is that it lists the files for me too, another solution is:

ls -d *-2015

It doesn't list me in subdirectories though. I used the following command but it didn't return any results:

find ./ -type d -regex '/\w-2015/'

Over the time I've worked with the JavaScript language, I've used different ways to create objects through what could properly be the emulation of a class (or object literal).

The forms I have worked with are the following:

1. Closures :

   var NombreClase = (function () {
       function NombreClase () {}
   
       NombreClase.prototype.metodo = function () {
           // código
       }
   
       NombreClase.metodoEstático = function () {
           // código
       }
   
       function metodoPrivado () {
           // código
       }
   
       return NombreClase;
   })();
   

2. Prototype ( prototype) :

   function NombreClase (arg1, arg2) {
       this.arg1 = arg1;
       this.arg2 = arg2;
   }
   
   NombreClase.prototype.metodo = function () {
       // código
   }
   
   NombreClase.metodoEstático = function () {
       // código
   }
   

3. Literal object :

   var NombreClase = {
       prop: 'foo',
       metodo: function () {
           // body...
       }
   };
   

I would like to objectively know what is the best way to use it? Is there another way? And why is it recommended?

I want to take the next sibling to a structure but I can't get it, taking into account that I have the following:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" />
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<div class="container">
  <div class="row list-items">

    <!-- Elemento que toma actualmente -->
    <div class="col-md-12">
      <div class="update-nag">
        <div class="update-split">
          <i class="glyphicon glyphicon-refresh"></i>
        </div>
        <div class="update-text">
          Lorem ipsum
          <a href="#">Lorem</a>
        </div>
      </div>
    </div>

    <!-- Elemento que hermano siguiente -->
    <div class="col-md-6">
      <div class="update-nag">
        <div class="update-split">
          <i class="glyphicon glyphicon-refresh"></i>
        </div>
        <div class="update-text">
          Lorem ipsum
          <a href="#">Lorem</a>
        </div>
      </div>
    </div>

    <div class="col-md-6">
      <div class="update-nag">
        <div class="update-split">
          <i class="glyphicon glyphicon-refresh"></i>
        </div>
        <div class="update-text">
          Lorem ipsum
          <a href="#">Lorem</a>
        </div>
      </div>
    </div>

  </div>
</div>

My XPATH path that takes the first element is:

//div[contains(@class, "list-items")]//div[@class="col-md-12"]

and I would like to be able to grab the next node, with something like:

//div[contains(@class, "list-items")]//div[@class="col-md-12"]//next-sibling

Can such a thing be done? How do I do it?

Added Details

I found on the internet the following two ways to deny:

• ?!
• [^\w]

But I can't find documentation in Spanish and English that they use to describe the operation, I consider it too advanced to understand the meaning of both and how to use them properly to obtain the expected result. The current answer fixes the problem but gives no usage definition.

Problem Statement

I want to select all those words that are not in quotes within a text. I know how to do the opposite.

Example:

Lorem ipsum "pain sit amet" , consectetur adipiscing elit, maecenas est felis "sit amet" .

With the following regular expression you could take the words that are in parentheses:

/"([\w\s]+)"/gim

The result

[
    1 => 'dolor sit amet',
    2 => 'sit amet'
]

What I look for

[
    1 => 'Lorem ipsum ',
    2 => ', consectetur adipiscing elit, maecenas est felis ',
    3 => '.',
]

Another example would be, from the following list:

• Hello
• hello
• hello
• hi*
• hello

Print / select those that do not use alphanumeric characters (I know how to take the opposite of the established indication). Take everything that is not an alphanumeric character, take all those words that do not have an "l", take everything that does not start with the letter "z", etc.

Working example: http://www.regextester.com/15

I would expect to do something like this for everything that doesn't start with "a":

/!^a.*/

But obviously it doesn't work for me, I'm waiting for your feedback.

Clarification

I would also like to understand the solution proposed and not just a copy-paste to solve the problem.

Note: The regular expression that I quote here to obtain the text works for me in PHP and JavaScript (languages ​​that I use to solve the problem), I have seen that there are small variations of regular expressions in the different languages ​​but between these 2 it is not something substantial. Therefore I would like the proposed solution to work in one of the 2.

Support sources

• http://www.regular-expressions.info/lookaround.html
• https://stackoverflow.com/a/406408/2578107

Sometimes I find that I need to validate if a variable has an array or object as its structure, in such a way that it can take a corresponding action depending on the type of value stored in the variable.

What would be recommended to distinguish between an array and an object?

Speaking of an object that is not the product of an instantiated function.

if (isObject(valor)) {
    /* Código */
} else {
    /* Código */
}

On many occasions I have required to take a value provided by the URLto carry out an action or simply to print said data to the user without having to go through a server-side language (either Python, PHP, Ruby, among others).

What is the best solution?