Asynchronous Programming - Reading Assignment

Javascript Programming
#61 
What is the difference between synchronous and asynchronous functions?

synchronous functions stops the program until the function return the result. However asynchronous functions start the action and program continue to run. And when the asynchronous functions finish it’s job, it return the result while program is working.

What is callback hell?
When we use several callbacks within callbacks, it is callback hell. Callback hell is working code, however it looks messy and it makes the code difficult to read and understand.

Which technique can help us solve callback hell?
using promises can help us to solve callback hell.

#62
  1. Synchronous functions are executing one by one and thus blocking other parts of code during that time, while asynchronous functions are executing interchangeabley and can wait on “their turn” (to be called).
  2. Callback hell is when there is to many call backs, to many nested functions to be executed.
  3. We can help to sove callback hell by synchronizing asynchronous tasks. Some of technique would be async.js, promises, generators and async functions.
#63

  1. Synchronus function or single-threaded only one task can be run at the time, the rest of the tasks is blocked by the browser until the task at hand is completed.
    Asynchronous function is initiated and then put aside until the callback from the server is received. In meantime other functions can be run.

  2. Callback hell can be unleashed when complex program containing lots of asynchronous functions requests many callbacks from the server at one time.

  3. We can avoid this mayhem by writing the asynchronous functions in the code synchronous way, using Meteors Fibers package or Fibres directly. This way we can maintain synchronous control flow.

#64

  1. Synchronous function is a flow when only one task can be run at the time. This tack occupied all browser’s attention till the task will be finished. Asynchronous functions can initiate different tasks and put them aside for a while new data arrived.

  2. When a nested function consists of many levels of asynchronous functions and getting too complex. This situation is called a callback hell.

  3. At the Node.js side we can write an asynchronous code looks like synchronous. At the browser side we can use promises.

#65
  1. A synchronous function is executed until its end, without getting interrupted by another task. An usynchronous function is executed, but can be interrupted by another task before it ends.

2.Callback hell stands for the high complexity of asynchronous handled nested functions.

3.Promises can be used to solve the problem call back hell. JQuery has a promise library included.

#66

  1. Asynchronous functions run until completed without interrupts. Synchronous functions can be set aside for a while and the environment can run multiple synchronous functions.

  2. When we nest too many synchronous functions, callbacks might be waiting for callbacks of callbacks. Callback hell

  3. Callback hell is dealt with promises - jQuery library used to chain callbacks and deal with errors

#67

Difference between synchronous and asynchronous functions.
Synchronous function runs the Javascript code in a linear fashion (single-threaded) whereas, asynchronous may have more than one thread running in the background.

What is callback hell?
Callback hell occurs when there are many levels of nested functions

Which technique can help us solve callback hell?
jQuery Promises, which enables us to chain callbacks.
Meteor can help also, using the Fibers package. It will allow us to build code that will appear to be synchronous, but in fact is able to run as asynchronous.

#68

What is the difference between synchronous and asynchronous functions?
A synchronous function blocks the JavaScript engine from other tasks to execute. On the other hand asynchronous functions can be initiated and then put aside while other tasks can be executed .
What is callback hell?
A callback hell refers to an undesirable nested code produced when dealing with callback functions.
Which technique can help us solve callback hell?
In the browser, a common pattern to deal with callback hell is the use of promises. For example, jQuery ships with a simple built-in promise library that enables us to chain callbacks and deal with errors.
But in Node.js, we can use a different approach. By extending the runtime, we can abstract away the asynchronicity and write code that looks sychronous.
Source: Discover Meteor

#69 
What is the difference between synchronous and asynchronous functions?

Synchronous function handles processes one at a time until they’re completed and asynchronous functions can be initiated and put on “hold” until they’re called upon.
What is callback hell?
It’s when you have multiple levels of nested functions that are all sitting in cue waiting to be completed.
Which technique can help us solve callback hell?
We can use promise libraries that will chain the functions together or use node.js to give more time to the processes to function.

#70

  1. What is the difference between synchronous and asynchronous functions?
    Synchronous functions are functions that can only run after the previous one has finished running. No more than one function will be able to run at the same time in this case.
    On the other hand, asynchronous functions are functions that are initialised while another function runs. This means that once the previous functions ends running, the one that we’ve initialised before will now run.
    This is done through a callback, which means a function that will run once the conditions for it to run are met, and this won’t stop other functions to run in the meanwhile.

  2. What is callback hell?
    It’s what is known as the total of callbacks that can exist in complex operations. The more nested operations there are, the more functions will run in an asynchronous way, waiting for their conditions to be met.

  3. Which technique can help us solve callback hell?
    We can use Promises, which enables us to chain callbacks and deal with errors.

#71

  1. Synchronous functions is called one at a time, they can’t be called at the exact same time, but rather after eachother.
    Asynchronous fuctions (can be thirdparty code or APIs) is called and when the function gives a reply then the code can be run. The code isn’t waited for until it replies because there can be other code that can be run immediately during the waittime for example the API to reply.

  2. A callback hell is when you create for example nested functions in nested functions creating levels and sub-levels in levels. In other words functions in other functions which in the end is in another function. It becomes a long code to run with functions behind functions.

  3. Promises help to deal with callbacks. Node.js writes code that looks synchronous to make it solve that problem.

#72

What is the difference between synchronous and asynchronous functions?

  • synchronous function: a function draw JAVA Script full attention
  • asynchronous function: can be initiated and then put aside until a later date to do
    What is callback hell?
  • a massive layer of callback nexted to each other
    Which technique can help us solve callback hell?
  • promises. jQuery ships with a simple built-in promise library that enables us to chain callbacks and deal with errors.
#73

  1. Synchronous functions are those that can only executed one at a time, and only allow the next function to be initiated after the first function is ran, Asynchronous functions are those that allow code to run simultaneously, they do not wait until one function is complete to run another function.

  2. Callback hell is a term used to describe an undesirable data structure where functions are nested inside another. They make the code messy and difficult to read.

  3. Promises are used to solve the call back hell problem.

#74 
What is the difference between synchronous and asynchronous functions?
  • syncronous functions are blocking… ie once it starts, it wont allow anything else to run until it has finished. This is problematic when talking to other servers across a network, or even reading a file from the local hard drive - they take valuable time when nothing else is allowed to run.
    Asynchronous functions however are non-blocking, in that they can start a process, and then allow other parts of the program to run whilst waiting for the finalisation of that process.
    What is callback hell?
  • often, when writing large JS programs, many chains of functions are run once the previous one is completed. Callback Hell is the name given to the situation that can occur frequently where there is a large number of functions all called via callback in one statement.
    Which technique can help us solve callback hell?
  • the notion of ‘promises’ is used to solve callback hell. Functions are written whereby a ‘promise’ is the return of the function that needs to be run in an asynchronous fashion. Promises make it possible to write code that looks much more readable - similar to syncronous code - where at is actually runs asynchronously.
#75

  1. Synchronous code blocks execution until it is finished, whereas asynchronous code pushes its operations onto the event loop waiting for an event to signal completion, and continues to execute the program’s code in normal flow.

  2. Complex amounts of function nesting that make code difficult to understand.

  3. By utilizing the Promise pattern to wrap function calls in a way that allows them to be chained in a much more readable manner than with standard callbacks. Promises in JavaScript allow for the developer to provide a callback function for branching execution: do this function if the operation results in success, and do this one if it fails. This is very powerful.

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#76
  1. What is the difference between synchronous and asynchronous functions?
    Synchronous functions are executed sequentially from top to bottom and javascript waits to finish one before executing another one. An asynchronous function can be initiated and then put aside until a later date while javascript gets started on the next task on its to-do list which is called the event loop.
  2. What is callback hell?
    Callback hell occurs when you have an excessive number of callbacks nested within one another, making the code overly complex to manage.
  3. Which technique can help us solve callback hell?
    In the browser we can use promises to chain call backs. Or we can use the fiber package in Meteor. It extends the runtime so we can write code that abstracts away from a-synchronicity and looks synchronous.
#77
  1. Synchronous functions lock the attention of the program executing it until they are fully executed, and in the meantime, the program cannot do anything else. On the other hand, asynchronous functions can be “paused” for some time, and other fucntiions can be executed in the meantime
  2. Program needs to wait for responses from a big amount of functions
  3. With some special things called promises
#78

  1. What is the difference between synchronous and asynchronous functions?
    When you call a synchronous function, it must complete before any code external to the synchronous function can begin to execute. When you call an asynchronous function, the program can continue to concurrently execute code external to the function while the asynchronous function continues to run until it completes…

  2. What is callback hell?
    A callback is a function that is to be executed after another function has finished executing. Any function that is passed as an argument of another function is a callback function. Callback hell refers to code consisting of multiple nested callbacks which makes the code difficult to read and to debug.

  3. Which technique can help us solve callback hell?
    Two techniques for addressing callback hell are promises and Meteor.

  4. Promises: The promises object is one approach in JavaScript (browser-side) to deal with excessive callbacks and jQuery includes a promise library that enables chaining of callbacks and handling errors.

  5. Meteor: Meteor offers another approach whereby we can write asynchronous code that looks synchronous. Meteor makes use of Fiber and in particular the Future sub-library and can run on both the client and the server.

#79

What is the difference between synchronous and asynchronous functions?
in synchronous functions code is executed line by line, asynchronous function can be put aside and called back at any time
What is callback hell?
it is the situation where we have lots of nested functions
Which technique can help us solve callback hell?
in browsers - we use promises

#80

1.What is the difference between synchronous and asynchronous functions?
A synchronous function is when the computer only computes that particular function, and will not receive any other command nor respond to any other event whatsoever until it has completed the task at hand.

An asynchronous function is the opposite, where the browser is able to respond to other events, by initiating asynchronous tasks and putting them aside for a later time.

2.What is callback hell?
A callback is a function that responds not to a particular event caused by the user, but it can respond to a special ajax event caused by the browser. This way, the browser can run on its own, while waiting for the response to come back, and this will not hinder the browser.

Callback hell is when the code is overrun with such callbacks, resulting in multiple event handlers working within different nestings.

3.Which technique can help us solve callback hell?
Promises can be used to deal callback hell. For example, jQuery has a simple bulti-in promise library, giving us the tools to enable chain callbacks, and dealing with errors.

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