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some tricky javascript tests

I have collected some tricky tests of javascript that I encountered in job interviews, which are pretty interesting. They covered some essential aspects in Javascript that we might don’t pay attention in practice but very important.

couldn’t connect to server 127.0.0.1 error in mongodb

If this problem occurred in Ubuntu, try to remove the lock and repair mongo user, then restart the service:

sudo rm /var/lib/mongodb/mongod.lock
sudo -u mongodb mongod -f /etc/mongodb.conf --repair

sudo restart mongodb

sudo rm /var/lib/mongodb/mongod.lock

sudo -u mongodb mongod -f /etc/mongodb.conf --repair

sudo restart mongodb

the problem should be resolved.

How to remove ï»¿ from the beginning of a file in PHP

The best way to remove the special character of the beginning of a file in UTF-8 with DOM is to interpreter it correctly by PHP:

&lt;?php
   //Storing the previous encoding in case you have some other piece 
   //of code sensitive to encoding and counting on the default value.      
   $previous_encoding = mb_internal_encoding();

   //Set the encoding to UTF-8, so when reading files it ignores the BOM       
   mb_internal_encoding('UTF-8');

   //Process files...

   //Finally, return to the previous encoding
   mb_internal_encoding($previous_encoding);

   //Rest of the code...
  ?&gt;

<?php

//Storing the previous encoding in case you have some other piece

//of code sensitive to encoding and counting on the default value.

$previous_encoding = mb_internal_encoding();

//Set the encoding to UTF-8, so when reading files it ignores the BOM

mb_internal_encoding('UTF-8');

//Process files...

//Finally, return to the previous encoding

mb_internal_encoding($previous_encoding);

//Rest of the code...

How to clear mail queue in Synology

there is no option in admin interface to clear mail queue, the only way I found is via ssh, suppose you are …

Install redis as server in ubuntu

Step 1. download latest stable version of redis, and install it

cd /tmp
wget http://redis.googlecode.com/files/redis-2.2.12.tar.gz
tar -zxf redis-2.2.12.tar.gz
cd redis-2.2.12
make
sudo make install

cd /tmp

wget http://redis.googlecode.com/files/redis-2.2.12.tar.gz

tar -zxf redis-2.2.12.tar.gz

cd redis-2.2.12

make

sudo make install

It will install in global:

mkdir -p /usr/local/bin
cp -p redis-server /usr/local/bin
cp -p redis-benchmark /usr/local/bin
cp -p redis-cli /usr/local/bin
cp -p redis-check-dump /usr/local/bin
cp -p redis-check-aof /usr/local/bin

mkdir -p /usr/local/bin

cp -p redis-server /usr/local/bin

cp -p redis-benchmark /usr/local/bin

cp -p redis-cli /usr/local/bin

cp -p redis-check-dump /usr/local/bin

cp -p redis-check-aof /usr/local/bin

Control Node.Js server using upstart/monit

Environment: debian/ubuntu This script can monitor cpu/memory usage of your node application, and start/stop it via a web interface or command line …

Php header code

PHP header codes, for reference only:

// Use this header instruction to fix 404 headers
// produced by url rewriting...
header('HTTP/1.1 200 OK');
 
// Page was not found:
header('HTTP/1.1 404 Not Found');
 
// Access forbidden:
header('HTTP/1.1 403 Forbidden');
 
// The page moved permanently should be used for
// all redrictions, because search engines know
// what's going on and can easily update their urls.
header('HTTP/1.1 301 Moved Permanently');
 
// Server error
header('HTTP/1.1 500 Internal Server Error');
 
// Redirect to a new location:
header('Location: http://www.example.org/');
 
// Redriect with a delay:
header('Refresh: 10; url=http://www.example.org/');
print 'You will be redirected in 10 seconds';
 
// you can also use the HTML syntax:
// &lt;meta http-equiv="refresh" content="10;http://www.example.org/ /&gt;
 
// override X-Powered-By value
header('X-Powered-By: PHP/4.4.0');
header('X-Powered-By: Brain/0.6b');
 
// content language (en = English)
header('Content-language: en');
 
// last modified (good for caching)
$time = time() - 60; // or filemtime($fn), etc
header('Last-Modified: '.gmdate('D, d M Y H:i:s', $time).' GMT');
 
// header for telling the browser that the content
// did not get changed
header('HTTP/1.1 304 Not Modified');
 
// set content length (good for caching):
header('Content-Length: 1234');
 
// Headers for an download:
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="example.zip"'); 
header('Content-Transfer-Encoding: binary');
// load the file to send:
readfile('example.zip');
 
// Disable caching of the current document:
header('Cache-Control: no-cache, no-store, max-age=0, must-revalidate');
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); // Date in the past
header('Pragma: no-cache');
 
// set content type:
header('Content-Type: text/html; charset=iso-8859-1');
header('Content-Type: text/html; charset=utf-8');
header('Content-Type: text/plain'); // plain text file
header('Content-Type: image/jpeg'); // JPG picture
header('Content-Type: application/zip'); // ZIP file
header('Content-Type: application/pdf'); // PDF file
header('Content-Type: audio/mpeg'); // Audio MPEG (MP3,...) file
header('Content-Type: application/x-shockwave-flash'); // Flash animation
 
// show sign in box
header('HTTP/1.1 401 Unauthorized');
header('WWW-Authenticate: Basic realm="Top Secret"');
print 'Text that will be displayed if the user hits cancel or ';
print 'enters wrong login data';

// Use this header instruction to fix 404 headers

// produced by url rewriting...

header('HTTP/1.1 200 OK');

// Page was not found:

header('HTTP/1.1 404 Not Found');

// Access forbidden:

header('HTTP/1.1 403 Forbidden');

// The page moved permanently should be used for

// all redrictions, because search engines know

// what's going on and can easily update their urls.

header('HTTP/1.1 301 Moved Permanently');

// Server error

header('HTTP/1.1 500 Internal Server Error');

// Redirect to a new location:

header('Location: http://www.example.org/');

// Redriect with a delay:

header('Refresh: 10; url=http://www.example.org/');

print 'You will be redirected in 10 seconds';

// you can also use the HTML syntax:

// <meta http-equiv="refresh" content="10;http://www.example.org/ />

// override X-Powered-By value

header('X-Powered-By: PHP/4.4.0');

header('X-Powered-By: Brain/0.6b');

// content language (en = English)

header('Content-language: en');

// last modified (good for caching)

$time = time() - 60; // or filemtime($fn), etc

header('Last-Modified: '.gmdate('D, d M Y H:i:s', $time).' GMT');

// header for telling the browser that the content

// did not get changed

header('HTTP/1.1 304 Not Modified');

// set content length (good for caching):

header('Content-Length: 1234');

// Headers for an download:

header('Content-Type: application/octet-stream');

header('Content-Disposition: attachment; filename="example.zip"');

header('Content-Transfer-Encoding: binary');

// load the file to send:

readfile('example.zip');

// Disable caching of the current document:

header('Cache-Control: no-cache, no-store, max-age=0, must-revalidate');

header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); // Date in the past

header('Pragma: no-cache');

// set content type:

header('Content-Type: text/html; charset=iso-8859-1');

header('Content-Type: text/html; charset=utf-8');

header('Content-Type: text/plain'); // plain text file

header('Content-Type: image/jpeg'); // JPG picture

header('Content-Type: application/zip'); // ZIP file

header('Content-Type: application/pdf'); // PDF file

header('Content-Type: audio/mpeg'); // Audio MPEG (MP3,...) file

header('Content-Type: application/x-shockwave-flash'); // Flash animation

// show sign in box

header('HTTP/1.1 401 Unauthorized');

header('WWW-Authenticate: Basic realm="Top Secret"');

print 'Text that will be displayed if the user hits cancel or ';

print 'enters wrong login data';

dojo based Theme for YUIDOC

I just created a dojo based YUIDOC theme, it’s similar to Dojotoolkit Api. demo can be found here: YUI Api Doc Feature: …

get millisecond & unique timestampe in php

To get millisecond:

(float)microtime(true);

1	(float)microtime(true);

To get unique timestampe:

function uniqueTimeStamp()
    {
        $Asec = explode(" ", microtime());
        $Amicro = explode(".", $Asec[0]);
        return ($Asec[1] . substr($Amicro[1], 0, 4));
    }

function uniqueTimeStamp()

{

$Asec = explode(" ", microtime());

$Amicro = explode(".", $Asec[0]);

return ($Asec[1] . substr($Amicro[1], 0, 4));

}

preg_replace_callback in class

variable scope in PHP is painful. not like java or javascript, you can’t get preg_replace_callback works like this:

class test{
private $a = 'test';
public function foo($data){
   $a = $this-&gt;a;
   function nested($matches){
        return $matches[1].$a;
   }
   preg_replace_callback('/href=(.*?)/i','nested',$data);
}
}

class test{

private $a = 'test';

public function foo($data){

$a = $this->a;

function nested($matches){

return $matches[1].$a;

}

preg_replace_callback('/href=(.*?)/i','nested',$data);

}

what you have …