Asynchronous Programming - Reading Assignment

Javascript Programming
#242

thanks. Ill tell the others

#243
  • What is the difference between synchronous and asynchronous functions?

Synchronous and asynchronous functions differ based on when and where they are called. Synchronous functions are constantly running throughout the event loop of the script tag, while asynchronous functions are making contact with an outside server but not getting a response until ordered by the user.

  • What is callback hell?

Callback hell is the perfectionists nightmare. In order something that looks so easy we need several layers of nested functions that work perfectly with one another.

  • Which technique can help us solve callback hell?

In order to combat callback hell we can use ‘promises’ that chain callbacks together and deals with errors. Node.js also helps by allowing us to extend runtimes that allow for asynchronous code to look synchronous

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#244
  1. What is the difference between synchronous and asynchronous functions?

A synchronous task will occupy the computer until its completion, an asynchronous task can be initiated and then put aside until a later time while the computer gets started on the next task on its to-do list. Code which is asynchronous will not lock the browser up, no matter how long it takes.

  1. What is callback hell?

‘Callback hell’ is where there’s an excessive amount of function calls and the code has many many levels of functions.

  1. Which technique can help us solve callback hell?

Promises in jQuery.

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#245
  1. The synchronous function will block other functions from executing until it is completed. While the asynchronous function will be initiated and executed later, not blocking the thread.
  2. A callback hell occurs when there are many functions nested in the parent one. It will add unnecessary complexity to the program.
  3. In the browser, to deal with the callback hell it is to use promises.
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#246
  1. What is the difference between synchronous and asynchronous functions?
    synchronous functions occupy event hanlders until its completion. asynchronous can
    be put aside while the next one activates.
  2. What is callback hell? an abstract problem which creates the problem of readability of
    the code
  3. Which technique can help us solve callback hell? promises
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#247

  1. A synchronous function task will occupy all of the engine until the task is complete, am asynchronous task can be initiated and then put aside until later.

  2. Callback hell consists of several nested callbacks that make code hard to read and sometimes filled with bugs.

  3. The technique that can help us solve callback hell is promise, it allows us to chain callbacks and deal with errors in our code.

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#248

Glenn_CostaRica

1. What is the difference between synchronous and asynchronous functions?
Synchronous functions are a type of functions that do not allow other functions to run while they are running. Since the first instant that a synchronous functions starts running, this function monopolizes the JavaScript Engine. In the case of asynchronous functions, by contrast, the function can stop and wait for another function to execute and let the thread attend other task.

2. What is callback hell?
An important concept to cover first is the concept of CALLBACK FUNCTION: a function that is to be executed after another function has finished executing — hence the name ‘call back’. This important to note, since, in JavaScript, functions are objects. Because of this, functions can take functions as arguments, and can be returned by other functions… The callback hell is a condition where there are several (or many levels) or nesting of functions used as arguments of functions, in a way that code becomes extremely hard to read, to analyze or even to debug.

3. Which technique can help us solve callback hell?
One technique is Promises. Promises exist to address the problem of chained synchronous functions. Modern javascript libraries and frameworks like Angular and of course jQuery include the tool of Promises. Also, one means offered by Node.js is to extend runtime and allow the developer to enter asynchronous code in a synchronous style.

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#249

  1. Synchronous functions occupy JavaScript in the browser until they are completed, whereas asynchronous functions make it possible to handle other tasks while waiting the original function to complete.

  2. Asynchronous functions that become very complex and include a lot of nested callbacks and levels and sub-levels are referred to as “callback hells”.

  3. A common way to deal with excessive callbacks is to use “promises” that enable to chain callbacks and deal with errors. Promises are included in e.g. jQuery’s built-in library.

    Also, in node.js, when running JavaScript on the server, it’s possible to write asynchronous code in a synchronous way by extending the runtime.

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#250

  1. What is the difference between synchronous and asynchronous functions?
    Synchronous functions execute line by line and function by function. They cannot be interrupted to go to do something else.
    Asynchronous functions can be interrupted to allow another function to run. Once it is done running, it comes back to the interrupted function to finish the first task.

  2. What is callback hell?
    A callback is a promise of coming back to that line of code once the task is completed. What if the task never gets completed and the first function waiting for the callback never receives it? What if too many functions are waiting for callbacks? Callback hell happens!

  3. Which technique can help us solve callback hell?
    The use of promises, i.e. libraries that track callbacks and manage errors.

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#251
  1. The difference is in the level of resources required to perform tasks and in the time span in which it will be completed. Synchronous functions require full focus and the task will be addressed until it is completed, while asynchronous functions can be initiated and then put aside until other conditions are met (or tasks completed).
  2. A callback hell is a scenario in which there are too many nested functions related to a set of tasks, meaning that the layers of code which will have to be run are too many.
  3. In the browser through promises, in Node.js by extending runtime.
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#252

  1. Synchronous functions are blocking (only one thread is being executed). That means only one operation/calculation or whatever can be executed and be in progress at a time. An asynchronous function can be started and then (when it has to wait for some other information/data) another operation/task/calculation can be performed. The first initiated function will continue when the data arrived. Javascript is also a synchronous, blocking language (only one thread allowed). But you can it programmed it in a way that it behaves like a asynchronous language.

  2. To code asynchronous behavior (which is needed) in Javascript (mostly when communicating with a server) you have to synchronize these calls through nested callbacks. This means each function gets an argument which is again another function that is called with a parameter which is the response of the previous function

  3. To solve the problem of callback hells you can use Javascript Promises. In this method you still have to use callbacks, but the order of executing the functions is more straightforward and the code becomes easier to read

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#253
  1. What is the difference between synchronous and asynchronous functions?
  2. What is callback hell?
  3. Which technique can help us solve callback hell?

  1. Synchronous run the code until it’s complete, full attention given, single threaded and it’s also called blocking. Asynchronous can continue the rest of code at a later time and continue with the next task/event first and be called back later.

  2. When there are too many callbacks nested in the functions, callback hell happened.

  3. Promises which can chain the callbacks up and deal with the errors.

To be really honest these are just theory answers and I dont fully grasp how it actually works, especially the 3rd one. Until i test it in code, i will try to remember the concept.

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#254

  1. Synchronous functions run single threaded (i.e. executed one after the other). The next function won’t start until the current function has completed (aka blocking tasks). Whilst asynchronous functions register a callback (managed via an event loop in the background) that allows the program execution to continue to run other functions and return to the original function after the callback data has been obtained (e.g. from an API call).

  2. When it comes to asynchronous functions (such as asynchronous event handlers) they have two or more functions (e.g. the click event function and the callback function). As the complexity of the task to be handled increases the number of required callback functions also typically increases - which gives rise to the expression ‘call-back hell’ (i.e. an excessive number of callbacks).

  3. Promises is a pattern that can be used to deal with callback hell. jQuery has a simple promises library which enables us in JavaScript to chain callbacks and manage errors.

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#255

Excellent answers sir, you explain all your answer in a very strong detailed way! keep it like that! :muscle:

Carlos Z.

#256

  1. What is the difference between synchronous and asynchronous functions?
    Synchronous function are executed and completed, more or less, right away while asynchronous functions may no be. Synchronous functions are executed continuously while asynchronous functions are initiated and put aside.

  2. What is callback hell?
    Excessive sub-levels of nested function calls

  3. Which technique can help us solve callback hell?
    Promises to chain callbacks and deal with errors
    or simulated synchronicity with Fibers

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#257

  1. Sync funcs are labor intensive and can cause things to lock up and can’t be put on hold.
    Async funcs task can be initiated and set aside until later.

  2. When the level of nested functions and complexity becomes excessive.

  3. Promises

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#258
  1. What is the difference between synchronous and asynchronous functions?
    • Synchronous functions require complete execution before the next event is handled.
    • Asynchronous functions can be initiated and put aside. The next events can then be handled while waiting on a response for the asynchronous function.
  2. What is callback hell?
    • Callback hell is when there are multiple levels of asynchronous functions which results in nested functions upon nested functions.
  3. Which technique can help us solve callback hell?
    • When using Jquery, this can be done by utilizing promises.
    • When using Node.js, we can extend the runtime of the code such that we abstract away the asynchronicity and write code that looks synchronous.
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#259

// Hey Ivan, the link you provided for this exercise didn’t work for some reason. Anyway, good old Google helped.

1. What is the difference between synchronous and asynchronous functions?

The difference is that asynchronous functions open and then stand aside while the next function starts and then the next task until is called upon again, whereas synchronous will go over and over until the task is performed.

2. What is callback hell?

It is a complex of operations which tend to create still more levels and sub-levels.

3. Which technique can help us solve call back hell?

In JQuery is used promise library which is fulfilled or rejected, it is immutable or in Node.js we could use fibers package which presents an API to jump between multiple call stacks from within a single thread.

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#260

What is the difference between synchronous and asynchronous functions?

Synchronous functions

What is callback hell?

complex nested functions producing more levels and sub-levels to manage program flow control.

Which technique can help us solve callback hell?

Use promises or fiber package.

#261

  1. What is the difference between synchronous and asynchronous functions?
    A. Asynchronous function is one that blocks or occupies JavaScript until the function is complete. It can only complete one task at a time. An asynchronous function is one that can be executed and set aside while the program does other task.

  2. What is callback hell?
    A. An asynchronous function with many complex operations that produce many levels and sub-levels is called a callback hell.

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

1 Like