Web 开发问题汇总(一)

archives, web development

1. What is href=“#” and why is it used?

Solution:

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A hashtag - # within a hyperlink specifies an html element id to which the window should be scrolled.  
href="#some-id" would scroll to an element on the current page such as <div id="some-id">.

href="//site.com/#some-id" would go to site.com and scroll to the id on that page.  

href="#" doesn't specify an id name, but does have a corresponding location - the top of the page. Clicking an anchor with href="#" will move the scroll position to the top.

Reference:http://stackoverflow.com/questions/4855168/what-is-href-and-why-is-it-used

2. How to debug your web page, technology stack is LAMP.

Solution:View log, figure out what cause problems.

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$ tail -f /var/log/apache2/error_log
[Fri Dec 11 21:34:57.003657 2015] [:error] [pid 17465] [client ::1:50505] PHP Parse error:  parse error, expecting `','' or `';'' in /Users/dongmeiliang/Sites/knowledgeispower/includes/header.html on line 7
[Fri Dec 11 21:34:57.003701 2015] [:error] [pid 17465] [client ::1:50505] PHP Stack trace:
[Fri Dec 11 21:34:57.003723 2015] [:error] [pid 17465] [client ::1:50505] PHP   1. {main}() /Users/dongmeiliang/Sites/knowledgeispower/index.php:0

3. Install mcrypt_filter extension on El capitan

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// Please make sure the PHP extensions listed below are installed.
mCrypt

// PECL is a repository of PHP extensions that are made available to you via the » PEAR packaging system. 

// There are several options for downloading PECL extensions, such as:
o The pecl install extname command downloads the extensions code automatically, so in this case there is no need for a separate download.
o » http://pecl.php.net/ The PECL web site contains information about the different extensions that are offered by the PHP Development Team. The information available here includes: ChangeLog, release notes, requirements and other similar details.
o pecl download extname PECL extensions that have releases listed on the PECL web site are available for download and installation using the » pecl command. Specific revisions may also be specified.
o SVN Most PECL extensions also reside in SVN. A web-based view may be seen at » http://svn.php.net/viewvc/pecl/. To download straight from SVN, the following sequence of commands may be used:

$ pecl search mCrypt
Retrieving data...0%
Matched packages, channel pecl.php.net:
=======================================
Package       Stable/(Latest) Local
mcrypt_filter 0.1.0 (beta)          Applies mcrypt symmetric encryption using stream filters

$ pecl install mcrypt_filter
Failed to download pecl/mcrypt_filter within preferred state "stable", latest release is version 0.1.0, stability "beta", use "channel://pecl.php.net/mcrypt_filter-0.1.0" to install
install failed

$ pecl install channel://pecl.php.net/mcrypt_filter-0.1.0/mcrypt_filter
Attempting to discover channel "pecl.php.net/mcrypt_filter-0.1.0"...
Attempting fallback to https instead of http on channel "pecl.php.net/mcrypt_filter-0.1.0"...
unknown channel "pecl.php.net/mcrypt_filter-0.1.0" in "channel://pecl.php.net/mcrypt_filter-0.1.0/mcrypt_filter"
invalid package name/package file "channel://pecl.php.net/mcrypt_filter-0.1.0/mcrypt_filter"
install failed

$ pecl install channel://pecl.php.net/mcrypt_filter-0.1.0
Cannot install, php_dir for channel "pecl.php.net" is not writeable by the current user
DongMeiliangsMacBook-Pro:upload dongmeiliang$ sudo pecl install channel://pecl.php.net/mcrypt_filter-0.1.0
Password:
downloading mcrypt_filter-0.1.0.tgz ...
Starting to download mcrypt_filter-0.1.0.tgz (4,586 bytes)
...
checking for mcrypt support... yes, shared
configure: error: mcrypt.h not found. Please reinstall libmcrypt.
ERROR: `/private/tmp/pear/install/mcrypt_filter/configure --with-php-config=/usr/bin/php-config' failed

// Resolve configure: error: mcrypt.h not found. Please reinstall libmcrypt.
Get libmcrypt 2.5.8 from Sourceforge: http://sourceforge.net/projects/mcrypt/files/Libmcrypt/2.5.8/libmcrypt-2.5.8.tar.gz/download

$ tar -zxvf libmcrypt-2.5.8.tar.gz
$ mkdir -p /usr/local/src
$ mv libmcrypt-2.5.8 /usr/local/src/
$ cd /usr/local/src/libmcrypt-2.5.8/
$ ./configure --prefix=/usr/local
$ make && make install

// Continue install mCrypt extension
$ sudo pecl install channel://pecl.php.net/mcrypt_filter-0.1.0
...

12472464 40 -rwxr-xr-x  1 root  wheel  16704 Feb 15 21:41 /private/tmp/pear/install/pear-build-rootEyJ4Jg/install-mcrypt_filter-0.1.0/usr/lib/php/extensions/no-debug-non-zts-20121212/mcrypt_filter.so

Build process completed successfully
Installing '/usr/lib/php/extensions/no-debug-non-zts-20121212/mcrypt_filter.so'
ERROR: failed to write /usr/lib/php/extensions/no-debug-non-zts-20121212/mcrypt_filter.so (copy(/usr/lib/php/extensions/no-debug-non-zts-20121212/mcrypt_filter.so): failed to open stream: Operation not permitted)

We need to disable SIP.

OSX 10.11 El Capitan ships with a new security process referred to as SIP or Security Integrity Protection also known as rootless.

What this essentially does is protect certain system level directories from being changes, notably

o /System
o /sbin
o /usr
o not /usr/local

// Disabling SIP in OSX
o Reboot your Mac into Recovery Mode by rebooting and holding down ‘command’ + ‘r’
o Launch a Terminal session and enter csrutil disable
o Reboot

// Reinstall mCrypt extension
$ sudo pecl install channel://pecl.php.net/mcrypt_filter-0.1.0

...

Build process completed successfully
Installing '/usr/lib/php/extensions/no-debug-non-zts-20121212/mcrypt_filter.so'
install ok: channel://pecl.php.net/mcrypt_filter-0.1.0
configuration option "php_ini" is not set to php.ini location
You should add "extension=mcrypt_filter.so" to php.ini

Reference:http://www.nginx.cn/2196.html http://coolestguidesontheplanet.com/install-mcrypt-for-php-on-mac-osx-10-10-yosemite-for-a-development-server/

4.Install mcrypt for php on Mac OSX 10.11 El Capitan

o Disable SIP/rootless You need to disable the new System Integrity Protection to install into some system protected directories – this involves a recovery reboot and disabling with.

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$ csrutil disable

o Getting it on in OS X El Capitan 10.11

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$ cd ~ ; mkdir mcrypt ; cd mcrypt

Get libmcrypt 2.5.8 from Sourceforge, this is direct download link.

Get the php code in a tar.gz or .bz2 format- (version 5.5.27 is the one that currently ships with OSX 10.11)

Move both of these files that you downloaded into your working directory – mcrypt in this instance, and go back to Terminal

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$ cd ~/mcrypt

Expand both files via the command line or just double click them in the Finder:

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$ tar -zxvf libmcrypt-2.5.8.tar.gz
$ tar -zxvf php-5.5.27.tar.gz

o Configuring libmcrypt

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$ cd libmcrypt-2.5.8
$ ./configure
$ make
$ sudo make install

o Compile mcrypt php Extension

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$ cd ../php-5.5.27/ext/mcrypt/
$ /usr/bin/phpize
$ ./configure
$ make
$ sudo make install

o Enabling mcrypt.so php Extension

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// Open /etc/php.ini and add the line below at the end
extension=mcrypt.so

// If there is no php.ini file,  then you need to make one from php.ini.default in the same location like so:
$ sudo cp /etc/php.ini.default /etc/php.ini

// And allow write capability
$ sudo chmod u+w  /etc/php.ini

// Then add the line as above in your favourite text editor:
$ sudo vi /etc/php.ini

// make sure dynamic extensions are set to on…
extension_dl = On

// If it didn’t load you may need to declare the extensions directory in /etc/php.ini
extension_dir = "/usr/lib/php/extensions/no-debug-non-zts-20100525/"

o Restart Apache

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$ sudo apachectl restart

That’s it, create a php page with the function phpinfo(); to see if it loaded correctly.

Reference:http://coolestguidesontheplanet.com/install-mcrypt-for-php-on-mac-osx-10-10-yosemite-for-a-development-server/ http://coolestguidesontheplanet.com/what-is-sip-in-osx-10-11-el-capitan/

4. How to set up Apache MySQL PHP on Debian?

A:https://wiki.debian.org/LaMp

5. Where is apache error log path on Debian?

A:/var/log/apache2/error.log

6.

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$ php arrayTests.php
PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib/php/extensions/no-debug-non-zts-20121212/' - dlopen(/usr/lib/php/extensions/no-debug-non-zts-20121212/, 9): no suitable image found.  Did find:
  /usr/lib/php/extensions/no-debug-non-zts-20121212/: not a file in Unknown on line 0

A:这个问题的原因是本来我应该是设置 extension_dir 的，结果在 php.ini里写成了 extension， 更正之后问题就解决了。

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extension_dir = "/usr/lib/php/extensions/no-debug-non-zts-20121212/"

Reference:http://stackoverflow.com/questions/5282264/php-warning-php-startup-unable-to-load-dynamic-library

7.Why should the ‘&’ (ampersand) character be HTML escaped?

A:The reason we escape the & is precisely because it is the first character in special characters such as &rsquo. If it is not escaped, some programs may be expecting a special character to begin when they see the ampersand.

But it is only escaped when you actually want the ampersand to show. You would not escape it in a special character. So you would always use &rsquo and never &rsquo.

Reference:https://www.quora.com/Why-should-the-ampersand-character-be-HTML-escaped

8.Evaluate JavaScript in terminal on Mac

A:

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// 1.
$ osascript test.js
// 2.
// Use specified language and evaluate given script file
$jrunscript -l js -f test.js
$jrunscript test.js

9.How to debug JavaScript?

A: Reference:https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/Debugging_JavaScript

10.How to use WebSocket with an Apache server while main develop language is PHP?

A: One path is to use an independent installed web sockets server.

For PHP you can try: http://code.google.com/p/phpwebsocket/ or http://code.google.com/p/phpws/

There are some other projects which you can try as well.

Basically, you need to upload, unpack and start running the process.

On the frontend, you’ll have javascript connecting to the server on the specific port.

Most websocket servers have a demo which echoes back whatever it hears, so this is a good place to write some test code. You may even find a rudimentary chat implementation.

The tricky part is to monitor the web socket server and to make sure it runs smoothly and continuously.

Try to test on as many browsers/devices as possible as this will decide on which websocket server implementation you choose. There are old and new protocols you have to watch out for.

Reference:http://stackoverflow.com/questions/11334320/using-websocket-on-apache-server

11.How do I enable apache file and directory indexing under Linux or UNIX?

A:Under Apache web server automatic index generation is enabled with using Options +Indexes or Options Indexes directive. If a URL which maps to a directory is requested, and there is no DirectoryIndex (e.g., index.html) in that directory, then mod_autoindex will return a formatted listing of the directory.

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// Option 1: Using Apache config file
// Add directory option to Apache configuration file /etc/httpd/httpd.conf or /etc/apache2/apache2.conf:
# vi /etc/apache2/apache2.conf

// Add following code:
<Directory /var/www/domain.com/pdfs>
Options Indexes FollowSymLinks
</Directory>

// Save and close the file. Restart Apache:
# /etc/init.d/httpd restart

// OR
# /etc/init.d/apache2 restart

// Option 2: Using .htaccess Files with Apache
// You can place config line Options Indexes in .htaccess file. Make sure .htaccess file support is enabled.
// Change directory to pdfs
$ cd pdfs

// Open .htaccess file
$ vi .htaccess

// Append following apache directive:
Options Indexes

//Save and close the file.

Reference:How do I enable apache file and directory indexing under Linux or UNIX?

13.Twig:RuntimeException: Unable to create the cache directory

A:The reason is web run via user www that hasn’t right create cache directory in target position.

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sudo chown -R www:staff path/to/application

Reference:RuntimeException: Unable to create the cache directory

14.How to center a ul element?

A:

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ul {
    display: table;
    margin: auto;
}

15. 站内搜索引擎代码

A:

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<!--Google站内搜索开始-->
<form method=get action="http://www.google.com/search">
<input type=text name=q>
<input type=submit name=btnG value="Google 搜索">
<input type=hidden name=ie value=GB2312>
<input type=hidden name=oe value=GB2312>
<input type=hidden name=hl value=zh-CN>
<input type=hidden name=domains value="www.amznz.com">
<input type=hidden name=sitesearch value="www.amznz.com">
</form>
<!--Google站内搜索结束-->

<!--Yahoo站内搜索开始-->
<form action="http://www.yahoo.com.cn/search">
<input type=text name="p">
<input type="submit" value="Yahoo 搜索">
<input type=hidden name=vs value="www.amznz.com">
</form>
<!--Yahoo站内搜索结束-->

Reference:站内搜索引擎代码