Replace bower by NPM

Here is what I did when I tried to replace Bower by NPM for
MEANJS-0.5.0

bower configuration:
[gist https://gist.github.com/vanduc1102/dd97c58d5900655acb98d45b1505fa12]

That mean all the frondend libs will store in public/lib folder.

Now after I moved all the libs to package.json,
Oops, there is a small change, angular-bootstrap in will change to
angular-ui-bootstrap with NPM

[gist https://gist.github.com/vanduc1102/fb18241724ed4aacb6b8afb7b3ba2e62]

And a new gulp task:
[gist https://gist.github.com/vanduc1102/a70ed41f476dd4b5c6465747b18f88ea]

Update package.json
[gist https://gist.github.com/vanduc1102/d10d0c99ec1b4281c6a321e2ff213c67]

Javascript Promise chaining

Hi there here is the third post of Javascript/NodeJs callback.

We have an async task with Promise:

[gist https://gist.github.com/vanduc1102/d7c84cd605edf8d0faf1fb620556ba5f]

Create tasks function:

[gist https://gist.github.com/vanduc1102/d07c13973a4c3cda3973b12f6619f1b9]

Promise.all

execute all the promises at the same times, and resolve when all of the promises resolved

[gist https://gist.github.com/vanduc1102/8b85ee8ce42d23fb49ae9d165bb19794]

and reject when any of the Promise was rejected:

[gist https://gist.github.com/vanduc1102/09a90b3923ca1ba3d5d72630958e950a]

Promise.race

The Promise.race(iterable) method returns a promise that resolves or rejects as soon as one of the promises in the iterable resolves or rejects, with the value or reason from that promise.

[gist https://gist.github.com/vanduc1102/21ff8e6900ebfb1824c965fb1d654291]

Sequence Promises

Sometimes we need to do the jobs in sequences.
[gist https://gist.github.com/vanduc1102/5264a38f20f54d04360a191e53c5e7e3]

For promise functions with multiple parameters

[gist https://gist.github.com/vanduc1102/b15f3f2ff5733ebbc467464e96cdf2ea]

 

Online editor

https://repl.it/@vanduc1102/sequence-promises

 

 

Javascript Callback Hell and Promise

The last article with the callback, we use callback function to solve the issue with asynchronous in Nodejs/Javascript.
[gist https://gist.github.com/vanduc1102/5e2e7cea325e628ad91fa11f6170d7a1]

But life is not that easy; sometimes a task needs more effort to be done.
Let assumed our task splits into three tasks now:
[gist https://gist.github.com/vanduc1102/b63a58ef1751d231d9111339be09df46]

In other to finish a task we need a callback hell (http://callbackhell.com/):

[gist https://gist.github.com/vanduc1102/f679b6039afd1ba893b310ace5b93e87]

Gather all snippets together:

[gist https://gist.github.com/vanduc1102/b22979ea867d47777e413c0831402fef]

Result:



In reality, a task may need more and more sub-tasks, the nesting will be super crazy.

Now we speak about Promise. Let convert our simple task from callback to promise
[gist https://gist.github.com/vanduc1102/523f1ffb2dccb9cc80f49de2d79e5611]

And then we will use Promise chaining to solve the callback hell issue.

[gist https://gist.github.com/vanduc1102/0b03c51edd629f05e1ddec95c7a288a8]

The result:



 

Conclusion: To be honest I don't see my example has a clear explanation about Promise over Callback Hell, but you have to trust me, you will see Promise very helpful later.

 

 

 

NodeJS/Javascript callback

This article will show you the simple callback example.

Firstly, you have a task

[gist https://gist.github.com/vanduc1102/7e3ece4d85fe7265406e61dfa54b337c]

Result:



The code is very simple, each line of code is executed line by line the result is predicted. But life is not that easy because NodeJS and Javascript are single thread

For the I/O tasks like make AJAX requests, read a file or saving user profile to database it will take a little of time to get the task done

We will have this kind of code:
[gist https://gist.github.com/vanduc1102/540c1bd3a22ad26d83889456b3bc9cfa]

Result:



Oop! The result is out of control.

Now callback will help you.

[gist https://gist.github.com/vanduc1102/5e2e7cea325e628ad91fa11f6170d7a1]



That is the very first sight about callback.