Asynchronous Programming - Reading Assignment

Javascript Programming
#542

  1. Synchronous functions need to be executed and will block all other function until the task it is on is complete. Asynchronous functions can use callbacks, if the function is waiting for data and run other code until the data needed has arrived.

  2. Callback hell is when the program uses many callbacks it can be hard to know where the program is in terms of what is in the event loop, what has been calledback and has not been calledback.

  3. To help deal with callbacks we can use the promise feature on meteor. This helps to track the callbacks.

1 Like
#543
  1. Synchronous functions are executed one at a time whereby the next function can only be executed once the previous one is complete. Asynchronous functions can be executed prior to the completion of earlier functions as earlier functions can be put aside to be used at a later stage.
  2. Callback hell is when there are excessive function callbacks/nested functions, due to the complexity of the desired operation.
  3. Using JavaScript’s built-in promise library can help solve callback hell
1 Like
#544

  1. What is the difference between synchronous and asynchronous functions?
    Written in common words:
    Synchronous functions: Having the browser lock up while we wait for a call to finish would be like having Javes wait at the post office for the reply to every telegram he sends. This is where asynchronous functions come in: whereas a synchronous task will occupy Javes continuously until its completion, an asynchronous task can be initiated and then put aside until a later date while our valet gets started on the next task on his to-do list. You can think of it as Javes asking the post office to call him back when the reply arrives, at which point Javes can stroll back down there and get the mail.

  2. What is callback hell?
    A relatively simple operation requires usually a couple of levels of nested functions. So you can imagine that more complex operations tend to produce even more levels and sub-levels, which is what is poetically known as callback hell.

  3. Which technique can help us solve callback hell?
    In the browser, a common pattern to deal with excessive callbacks is to use promises. 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.

1 Like
#545

  1. What is the difference between synchronous and asynchronous functions?
    Аsynchronous functions and tasks can be initiated and then put aside while the next task on to-do list occures.
    Synchronous task occupy system continuously until its completion.

  2. What is callback hell?
    A callback hell is caused when people try to write JavaScript in a way where execution happens visually from top to bottom while using a lot of asynchronous functions (callbacks). The code will become really messy and hard to maintain depending on how many nested functions are used.

  3. Which technique can help us solve callback hell?
    By giving function names and declaring them at the top level, taking them out nested function, simplifies the reading of code. By making code modular, it allows code to be reused.
    In the browser, a common pattern to deal with excessive callbacks is to use promises. By extending the runtime, we can abstract away the asynchronicity and write code that looks sychronous.

1 Like
#546
  1. Synchronous functions operate one at a time and stop all other executions until they are done. Asynchronous functions executes in concurrence with other functions and dont need to wait for other functions to finish execution before they can go on ahead with what they’re doing.
  2. Callback hell is when many asynchronous functions are held up by waiting for other nested functions to finish execution, essentially holding up the whole process.
  3. With Promises and allowing our code to wait for others to finish executing so they have the appropriate resources to continue.
1 Like
#547

What is the difference between synchronous and asynchronous functions?
While synchronous functions are waiting for events to finish execution before moving to another in asynchronous functions events can run simultaneously.

What is callback hell?
Callback hell is when there are a lot of nested callback functions one within another.

Which technique can help us solve callback hell?
We can use promise libraries to solve callback hell situations. jQuery comes with a build-in promise library. in Node.js we can use Meteor

1 Like
#548
  1. Synchronous will wait until the task has completed while Asynchronous completes a task in background and can notify you when complete.

2.Callback hell is something a programmer never wants to experience. It’s basically function, within functions all waiting for one function to be callback it could create problems and become difficult when maintaining the code and being able to read.

3.The use of Promise’s is used to solve the callback hell, applications such as jQuery, AngularJS come with promise libraries and handle errors.

1 Like
#549

1. What is the difference between synchronous and asynchronous functions?
Asynchronous functions can be initiated and executed at a later time while other functions are being executed. Synchronous functions are continuously done in order until completion.
2. What is callback hell?
This is related to nested asynchronous functions creating a complex code structure.
3. Which technique can help us solve callback hell?
We can use JQuery changing nested asynchronous functions into chained synchronous functions.

1 Like
#550
  1. A synchronous function will occupy the javaScript engine until that particular function has been completed, whereas asynchronous functions allow the javaScript engine to continue with further programs whilst it is still waiting to complete previous tasks asked upon it.
    2.When a program has multiple sub levels of nested functions it needs to execute and wait for responses to complete, this can have lots of different responses it needs to move on and if a program gets larger and more complex with these sub levels of nested functions it is referred to as ‘call back hell’.
    3.Commonly to deal with excessive ‘callback hell’ we would use promises, Jquery has a built in library already available that enables us to chain callbacks and deal with errors. But in Node.js a different approach can be used, if we extend the run time on a callback, we can abstract away from asynchronicity and write code that looks synchronous.
1 Like
#551

  1. Synchronous tasks that occupys Javes’ full attention

  2. Asynchronous functions occupys Javes continuously
    until its completion.

  3. 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.

1 Like
#552

  1. Whereas a synchronous task will occupy JS continuously until its completion, on asynchronous task can be initiated and then put aside until a later date while it gets started on the next task.

  2. Callback hell is a phenomenon that afflicts a JS developer when he tries to execute multiple asynchronous operations one after the other. By nesting callbacks in such a way we easily end up with error-prone, hard to read and hard to maintain code.

  3. A common pattern to deal with excessive callbacks is to use promises. jQuery ships with a simple built-in promise library that enables us to chain callbacks and deal with errors.

1 Like
#553
  1. The difference between synchronous and asynchronous functions…

In a synchronous programming model, things happen one at a time. When you
call a function that performs a long-running action, it returns only when the
action has finished and it can return the result.

An asynchronous model allows multiple things to happen at the same time.
When you start an action, your program continues to run. When the action
finishes, the program is informed and gets access to the result (for example,
the data read from disk).

  1. Callback hell also known as pyramid of doom, subjective. A relatively simple operation requires three levels of nested functions. So you can imagine that more complex operations tend to produce even more levels and sub-levels, which is what is poetically known as callback hell.

  2. In the browser, a common pattern to deal with excessive callbacks is to use promises. jQuery ships with a simple built-in promise library that enables us to chain callbacks and deal with errors.
    :wink:

1 Like
#554

1 -> Synchronous basically means that you can only execute one thing at a time. Asynchronous means that you can execute multiple things at a time and you don’t have to finish executing the current thing in order to move on to next one.
2 -> a callback hell is a callback into a callback into a callback etc
3-> Using promises and/or Async

1 Like
#555

  1. Synchronous - a funtions that is blocking, or wholy occupying Javes:) with today’s PCs they are instant and don’t represent a big problem
    Aynchronous - a task that can be initiated and then put aside until later

  2. callback hell - when even a simple operation requires levels and sublevels of nested callback functions

  3. we can use Promises to deal with excessive callbacks.

#556
  1. Synchronous functions can only do one task then switch to the next, asynchronous can put a function on hold and call it when needed.
  2. Callback hell is when you need many complex operations, and you’ve written your code in a way that makes it keep calling back a function to be executed at a later date
  3. We can use promises to make a function look sychronous
1 Like
#557

  1. What is the difference between synchronous and asynchronous functions?
    When a synchronous function is called, the program will put all resources into completing the function before it executes other tasks. With an asynchronous function, the program will initiate the function, put it on hold, and can then switch to other tasks while waiting for a condition to be fulfilled (for example, a signal from a server) before going back to execute the rest of the asynchronous function.

  2. What is callback hell?
    Callback hell is an excessive number of nested sub-functions within an asynchronous function. The asynchronous function may hold while waiting for a trigger event to happen before executing each sub-function.

  3. Which technique can help us solve callback hell?
    Callback hell can be handled with promises in Javascript.

1 Like
#558

synchronous functions block the program execution until they are finished, while asynchronous functions permit multitasking, in the sense that they send the request and free the program execution until they are called back
2. with many asynchronous callback functions in complex code we can get lost and confused with difficulty i reading the code and finding bugs - this mess is call callback hell.
3.Promises can be used to write asynchronous code that still appears as though it is executing in a top-down way.

1 Like
#559

  1. Synchronous will run one thing at a time, basic functions. Asynchronous will run multiple layered and sub-layered operations, which can intiated without having to execute immediately, it can be allowed to run until a later execution.

  2. Callback hell is a complex operation with multiple levels and sub-levels of nested functions.

  3. Common patter to deal with excessive callbacks is to use promises. JQuery promise library enables to chain callbacks.

1 Like
#560

  1. Synchronous functions are those that are ‘blocking’ that is to say that they occupy the Javascript engine until their execution is finished. Asynchronous function on the other hand do not block the Javascript thread, instead they wait for execution to complete while the thread does other work.

  2. Callback hell is an undesirable situation whereby several nested callback functions are needed in order to perform relatively simple tasks. This makes our code harder to write, debug and maintain.

  3. We can use promises to solve the problem of call back hell. Promises help us to deal with chained synchronous functions and allows us to also handle errors. Modern javascript libraries and frameworks like Angular and jQuery come with a promise library. Another way of dealing with callback hell in Node.js is to extend the runtime and and abstract away the asynchronicity so as to allow the programmer to write asynchronous code in a synchronous style.

1 Like
#561
  1. What is the difference between synchronous and asynchronous functions?
    synchronous means that only one task can be completed at a time. This is also called blocking and it is when the task takes the full attention of the Java script engine.
    For asynchronous means that a task can be set aside and wait on a call back before resuming execution. This will allow the browser not to be blocked and other task can be complete.
  2. What is callback hell?
    Call back hell is when using asynchronous programming and waiting on multiple task to send a request back to resume execution of the next function.
  3. Which technique can help us solve callback hell?
    To solve call back hell you can use promises to enable you to chain call backs and deal with errors as one option, Another option is to use Meteor to extend runtime by using a Fibers package. You are then able to abstract away the asynchronous and write code that looks synchronous. Fibers does not really make asynchronous code synchronous. It just lest you write code in a synchronous style with synchronous control flow.
1 Like