Category Archives: Uncategorized

Installing mongodb on Ubuntu

ref –

Step 1 — Installing MongoDB

Ubuntu’s official package repositories include an up-to-date version of MongoDB, which means we can install the necessary packages using apt.

First, update the packages list to have the most recent version of the repository listings:

sudo apt update
Now install the MongoDB package itself:

sudo apt install -y mongodb
This command installs several packages containing the latest stable version of MongoDB, along with helpful management tools for the MongoDB server. The database server is automatically started after installation.

Next, let’s verify that the server is running and works correctly.

Step 2 — Checking the Service and Database

The installation process started MongoDB automatically, but let’s verify that the service is started and that the database is working.

First, check the service’s status:

sudo systemctl status mongodb

sending off questions and answers data

Regular Expressions (js)

new style

literal style



Found “ryu” at position 6 in string “shooo ryu ken ryu Ryu rYu ryU!”
Found “ryu” at position 14 in string “shooo ryu ken ryu Ryu rYu ryU!”
Found “Ryu” at position 18 in string “shooo ryu ken ryu Ryu rYu ryU!”
Found “rYu” at position 22 in string “shooo ryu ken ryu Ryu rYu ryU!”
Found “ryU” at position 26 in string “shooo ryu ken ryu Ryu rYu ryU!”

After replacement: shooo ryu ken ryu ryu ryu ryu!

wait for async code in a callback function


We have a function that does some processing. Then it executes a callback function.

So say we call function A, and provide an anonymous callback function.

Under this case, we will get the true in function A’s definition.
Everything is synchronous so we go step by step.

The Problem

The problem happens when we have asynchronous code in our callback

Given definition A:

In our callback definition, we do something asynchrnous. It returns true after 2 seconds.

This is a problem because while the execution is happening for the setTimeOut of waiting 2 seconds, our main execution
continues and our reply will be undefined.

The Solution

The solution is to use Promises. In this particular case, I will use jQuery’s Deferred, which is exactly the same as Promise, except its packaged in jQuery’s API.

1) chain the ‘then’

In order to wait for the async to finish, we call the callback function, and then chain the API call ‘then’ in order to continue with the results. This is assuming we declared a Promise object and returned it in cbConfirmed(). (we’ll get to this in the next step)

When you chain the then call, it will wait for async code to finish, then you simply provide an anonymous callback function inside to get the results.

2) declare and return the Promise object

3) call resolve and use it where the async code has finished

The main execution will wait for the callback to finish. After 2 seconds, the callback returns and gives the result to function A.

quotes on love and relationship

爱是什么? 当两端有足够的空间时,爱就会让两个人坐在长凳的中间。

num of lines v2

todo –

given a that a previous space exists:

usually when we pass the limit with a letter, we shift down to the next line, and keep going with the word after the ‘previous space’.

“abcde fghijk”(‘l’ passed limit)



However, there is a case where if the offending letter that went passed the limit has a space for the next value….

for example, given “abc def ghi jkl mno”…

abc def ghi (‘i’ passed limit)

then in this particular situation..

1) we include the offending letter as the previous string
2) break line
3) start next line with space

“abc def ghi”
” jkl mno”



try it: using height

font-family: ‘FSElliotPro’
font-size: 14px

double line with ellipsis

Chaining Promises