Asynchronous Programming - Reading Assignment

Javascript Programming
#602

  1. Synchronous functions can only be executed one at a time and needs to be completed before moving to the next function. Asynchronous functions on the other hand can be called/initiated and be put aside

  2. Complex nested function calls

  3. By using promises(jQuery built-in promise library)

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#603
  1. What is the difference between synchronous and asynchronous functions?

Synchronous is when javascript cant continue until the task is done and asynchronous is when javascript can continue while the task is being loaded.

  1. What is callback hell?

When you have a lot of synchronous code that is dificult to maintaine and read.

  1. Which technique can help us solve callback hell?

Promises

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#604
  1. A synchronous function is a JavaScirpt function that occupies JavaScript’s full attention. Meaning that when a synchronous function is being executed, the web browser is unable to execute any other task until the synchronous task is complete.

An asynchronous function is one in which tasks can be initiated and set aside until a “callback” returns to our code signaling that the task is complete.

  1. a Callback hell is when a code has several layers of callbacks or nested functions that work to send data our JS code is waiting for back to our JS code.

  2. We can deal with callback hell through promises libraries which enables us to chain callbacks and deal with errors. We can also, through using Node.js, we can write the code of our function to appear synchronous. By using fibers through a futures sub-library we can take the asynchronous function and build a synchronous equivalent.

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#605

  1. What is the difference between synchronous and asynchronous functions?
    Synchronous functions take all javascripts processing and do so one segment of code at a time. Asynchronous functions can be initiated and then put aside until they are actually needed.

  2. What is callback hell?
    Callback hell is the term for the increase in nesting that can occur when complexity of operations increases.

  3. Which technique can help us solve callback hell?
    In-browser, promises are used to chain-callbacks and deal with errors. In node.js it is solved by simulating synchronous control flow while remaining asynchronous.

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#606
  1. What is the difference between synchronous and asynchronous functions?

Synchronous code in Javascript will start from the top of the file and execute all tasks code one line at a time until it reaches the bottom. This means say you have three lines of code that must run. synchronous code will run it 1,2,3. but say the line of code for 2 is very long and the code must also be executes after setTimeout, for example, this will hold up the entire code that must run after 2. Only when 2 is done, 3 will then run.

With Asynchronous Code the JavaScript gets a little helper called the Web API. It takes task like number 2 and do it in the back ground. While 2 is busy in the back ground JavaScript continue with the following line of code. Number 2 will be displayed once it is done. so the task will be in the following order. 1,3,2. This helps us carry on with other task and not hold up the other code. Your browser will not hang or be occupied by this one task.

  1. What is callback hell?

A callback is a function that is passed to another function as a paramater. It is complex systems that requires loads of levels and sub levels of nested code. So lot of the functions get nested together. This means we can easily end up with error-prone, hard to read and hard to maintain code.

  1. Which technique can help us solve callback hell?

Promises is used to solve the callback hell. This method did not remove the use of callbacks, but it made the chaining of functions straightforward and simplified the code making it much easier to read and maintain.

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#607
  1. Synchronous functions run the order in which they are call, and can only be run one at a time. Asynchronous function allow one program to “pause” until later and complete another task and then come back to finish the first function.
  2. When you nest function inside of function reaching many sub-levels that will make it very strenuous for the system and difficult to track errors.
  3. Using a promise to reduce the number of layers of needed.
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#608

What is the difference between synchronous and asynchronous functions?

In Synchronous Javascript, when we run the code, the result is returned as soon as the browser can do. Only one operation can happen at a time because it is single-threaded. So, all other processes are put on hold while an operation is executing.

Asynchronous way: It never waits for each operation to complete, rather it executes all operations. The result of each operation will be handled once the result is available.

What is callback hell?

This is a big issue caused by coding with complex nested callbacks. Here, each and every callback takes an argument that is a result of the previous callbacks. In this manner, The code structure looks like a pyramid, making it difficult to read and maintain. Also, if there is an error in one function, then all other functions get affected.

Which technique can help us solve callback hell?

JavaScript provides an easy way of escaping from a callback hell. This is done by event queue and promises.

A promise is a returned object from any asynchronous function, to which callback methods can be added based on the previous function’s result.

  • Promises use .then() method to call async callbacks. We can chain as many callbacks as we want and the order is also strictly maintained.
  • Promises use .fetch() method to fetch an object from the network. It also uses .catch() method to catch any exception when any block fails.
  • So these promises are put in event queue so that they don’t block subsequent JS code. Also once the results are returned, the event queue finishes its operations.
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#609
  1. Synchronous functions are functions that are executed until they end, without getting interrupted by another task. They can be thought of as Single-Tasking Functions.
    Asynchronous functions executes, while also carrying out another task before it ends. They can be thought of Multi-Tasking Functions.

2.Callback hell is the complexity of simple operations when done with an asynchronous function.

3.JQuery “Promise Library” which enables the chaining of callbacks and dealing with errors is used to solve callback hell…

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#610

1 - In single-threaded environments, only one section of code can be executed before the next section can be executed. These tasks that require Javascript to focus one one section of code at a time are known as synchronous functions. Asynchronous functions are the opposite to synchronous functions. These functions can be called upon, the put to one side before being fully executed at a later date. Javascript manages its workload using an event-loop, which keeps track of which tasks need to be executed - because Javascript is single-threaded, the Javascript engine has a built-in background thread that manages the event-loop.
2 - Callback hell is where the main function may contain multiple nested functions inside - to perform even the simplest of tasks - this can be “hell” when writing and using complex code, as they can be very difficult to maintain and debug.
3 - To help solve this issue of callback hell, promises are used. Libraries such as jQuery have built-in promise libraries that help us to chain callbacks to run multiple commands on the same element. Node.js allows us to extend the runtime by allowing us to write asynchronous code in a synchronous manner - reducing the abstractness that comes with asynchronous code, making it easier to both read and maintain.

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#611

1.Synchronous operations block instructions until a task is complete while asynchronous operations can execute without blocking other operations.

  1. It is phenomenon caused by executing multiple asynchronous callback operations. A callback operation typically involves a main function passing another function as one of it’s parameter. When the main function has completed the passed function will be executed This can be nested to several levels and as such referred as Callback hell.

  2. Techniques to help solve this problem are;-

JQuery library which uses “promises” to chain callbacks and deal with errors.
Or software like Node.js and Fibers to make asynchronous events look synchronous.

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#612

  1. What is the difference between synchronous and asynchronous functions?
    Synchronous functions occupy JS continuously until the function is completed.
    Asynchronous functions can be occupied and put aside for a later moment.

  2. What is callback hell?
    Lots of nested arguments.

  3. Which technique can help us solve callback hell?
    The use of promises.

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#613

What is the difference between synchronous and asynchronous functions?

  • synchronous - run one function/task at a time
  • Asynchronous - multiple functions can be run at the same time
    * parallel programming…

What is callback hell?

  • In asynchronous javascript the subtask needs multiple levels of call backs are needed.

Which technique can help us solve callback hell?

  • The use of ‘promises’
  • Or with node.js running more synchronously on the client code.
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#614
  1. What is the difference between synchronous and asynchronous functions?
    Synchronous function keeps browser occupied while asynchronous gives an ability to execute other commands while wating for the previous one
  2. What is callback hell?
    Having to execute multiple complex operations and figuring out which nested callback is being called
  3. Which technique can help us solve callback hell?
    Using promises can solve callback hell situation
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#615

  1. synchronous code locks up the browser until it is done being completed, meaning no other codes are being executed or ran at the same time.
    asynchronous functions do not lock up the browser and allows javascript to move on to begin executing the next code until the original function is ready to complete.

  2. Even a relatively simple operation may require three or more levels of nested functions. As operations get more complex even more leves and sub levels are created, this is known as Callback hell. ,

Basically arguments, within arguments, within arguments, within arguments all waiting for one argument to callback to the other just to start another.

3.Different programs use different solutions to callback hell. One solution is what are called “promises”.

jQuery ships with a
simple built-in promise library that enables us to chain callbacks and deal with errors.

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#616

  1. What is the difference between synchronous and asynchronous functions?
    Synchronous means that you can only execute one thing at the same time. Asynchronous means that you can execute multiple things and you don’t have to finish executing one thing in order to move on to the next.

  2. What is callback hell?
    Codes with complex nested callbacks. Callbacks which takes an argument that is a result of the previous callbacks. Therefor the code structure looks like a pyramid, making it diffucult to read and maintain. Also, if there is an error in one function, then all other functions get affected.

  3. Which technique can help us solve callback hell?
    You can escape the callback hell by promises.
    A promise is a returned object from any asynchronous function, to which callback methods can be added based on the previous function’s result.

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#617

  1. Synchronous functions are executed no matter what, in the order it is coded although asynchronous function stops the program until the expected response (promise) is received.

  2. This is a situation when there is many entangled callback function and the code gets messy.

  3. Make the code modular, use await functions and promises

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#618

1- Synchronous is a simple one flow reading of the code in which every operations wait for the previous one to be over. In the asynchronous, several operations can be conducted at the same time, or more precisely put in pause in order for the next one to be executed.
2- A callback hell is when you have many functions imbricated inside each others
3- One can use promises.jquery

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#619

  1. Whereas a synchronous function will occupy the program continuously until its completion, an asynchronous function can be initiated and then put aside until later while our the main control flow continues.

  2. Using a lot of asynchronous functions which are nested and make the program increasingly complex.

  3. Promises

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#620

What is the difference between synchronous and asynchronous functions?
Synchronus functions block other functions while they are running.
Asynchronus functions can be set aside until later while other tasks can be finished.

What is callback hell?
Complex operations that produce a lot of levels and sub-levels of functions.

Which technique can help us solve callback hell?
Using promises from jQuery or building synchrinous equivalents of asynchrinous functions.

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#621
  1. Synchronous functions block each other from running until the first one is completed. Asynchronous functions on the other hand can be initiated and then put aside until a later date.
  2. When we have a lot of levels and sub-levels of nested functions.
  3. We can use promises in the browser while in Node.js we can extend the runtime.
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