Meseret Gebre » Tips and Tricks

Quick Tip JavaScript strings to numbers

mez — Wed, 06 Oct 2010 01:24:43 +0000

This tip is really just different ways to convert strings to numbers. Did you know that the follow code works just fine:

var string_to_number = "10" * "10"; // result 100

I thought that was cool, but funky right? Note, this does not work with the “+” operator. So a cool way to convert a string into a number is to do the following cool trick:

var string_to_number = "200" - 0; // result 200 booyah!

That is it for this tip and trick. Let me know if you come across a neat tip.

Quick Tip JavaScript concat operator

mez — Wed, 06 Oct 2010 01:07:41 +0000

JavaScript has string concatting built into the langauge for example.

var hello = "hel" + "lo"

This is not the interesting point I wanted to talk about. It actually gets more interesting on what happens when you concat
string literals with numbers. For example:

var x = "33" + 3 // result "333"

Notice the above example the number 3 was concatted with the string “33″ that result in the string “333″.
However can you guess what would happen if the number came first? More importantly what happens in this next example:

var x = 3 + 3 + "33" // result "633"

This is entirely different if you had done the values in a different order, for example:

var x = "33" + 3 + 3; //result "3333"

So be careful with this gotcha.

Mysqld_safe not starting mysql5?

mez — Fri, 04 Jun 2010 07:15:05 +0000

So I use macports to install mysql5 and when I was ready to start mysql using mysqld_safe, which is located:

/opt/local/bin/

I ended getting a big error report which said something along the lines of:

mkdir: /opt/local/var/run: No such file or directory
chown: /opt/local/var/run/mysql5: No such file or directory
chmod: /opt/local/var/run/mysql5: No such file or directory

Solution
I solved this by doing the following:

Make sure you have ran the following command after the install completes:
```
sudo /opt/local/lib/mysql5/bin/mysql_install_db  --user=mysql
```

Finally you have to do the following:

sudo mkdir /opt/local/var/run
sudo chmod g+w /opt/local/var/run/
sudo mkdir /opt/local/var/run/mysql5
sudo chown mysql /opt/local/var/run/mysql5/

Now you should be able to start mysql with no problems! A little bonus is create alias for starting and stopping mysql. My MBP is running Snow Leopard so I edit:

 ~/.profile

and add the following at the end of the file:

alias mysqlstart='sudo /opt/local/bin/mysqld_safe5 &'
alias mysqlstop='/opt/local/bin/mysqladmin5 -u root -p shutdown'