Asynchronous Programming - Reading Assignment

[illyushin]

Synchronous functions are functions that blocks JS to work on something else outside the function that is beeing needed. Asynchronous functions do not block JS like that, it can be initiated and then put aside until a later date

Callback hell is the state that you have when an operation has many levels of nested functions

For jQuery, you have a built-in promise library that enables us to chain callbacks and deal with errors.

[cherrybluemoon]

[Ray]

1. 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. Callbacks within callbacks, within callbacks to a degree when maintaining and reading a program becomes messy.
3. The use of Promises can solve a callback hell situation

[Fclriygphttic]

1. What is the difference between synchronous and asynchronous functions?
   the difference between synchronous and asynchronous is, synchronous is continuously happening until its complete, and asynchronous is completing given tasks, and then setting it aside until called.

2. What is callback hell?
   Callback hell is when multiple nested callbacks are needed for something. more nested functions the more complex it is, and that is why it is known as callback hell.

3. Which technique can help us solve callback hell?
   promises are a technique used to solve callback hell , jQuery holds a library to chain callbacks and fix errors.

[Mercurio]

Hello,

1. a synchronous function is a function the computer processes that must be executed in its entirety, and the computer cannot otherwise perform other task in parallel. An asynchronous task is a task that can be begun, set aside, and then completed at a later time. When set aside, other functions can be performed.

2. You have a callback when an event, which was previously set aside, is called back via Ajax. The event might have been originally triggered by a click requesting data, but being the click long gone, the callback is had when the data arrives. These events and their callbacks might be nested at a variety of sub levels within a function. This is callback hell.

3. Callback hell can be mitigated with the use of promises, a dedicated built in library. Otherwise you can setTimeOut.

Best

[JesusIsLord]

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

JavaScript is a synchronous, blocking, single-threaded language. That just means that only one operation can be in progress at a time.

Asynchronous callbacks allow you to invoke a callback function which sends a database request (and any other nested callbacks) off to your app, where it waits for a response from the database, freeing up the rest of your code to continue running.

2. What is callback hell?

The cause of callback hell is when people try to write JavaScript in a way where execution happens visually from top to bottom.

Callbacks are just the name of a convention for using JavaScript functions. There isn’t a special thing called a ‘callback’ in the JavaScript language, it’s just a convention. Instead of immediately returning some result like most functions, functions that use callbacks take some time to produce a result. The word ‘asynchronous’, aka ‘async’ just means ‘takes some time’ or ‘happens in the future, not right now’. Usually callbacks are only used when doing I/O, e.g. downloading things, reading files, talking to databases, etc.

However, functions that are async and use callbacks don’t return anything right away.

3. Which technique can help us solve callback hell?

1. Don’t nest functions. Give them names and place them at the top level of your program
2. Use function hoisting to your advantage to move functions ‘below the fold’
3. Handle every single error in every one of your callbacks. Use a linter like standard to help you with this.
4. Create reusable functions and place them in a module to reduce the cognitive load required to understand your code. Splitting your code into small pieces like this also helps you handle errors, write tests, forces you to create a stable and documented public API for your code, and helps with refactoring.

[cryptokaritz]

1. Synchronous functions block the program until it finishes the function task.
   Asynchronous functions do not block the program and can carry on other tasks while the function task is completed.
2. Callback hell happens when there are multiple nested functions for more complex operations that create more levels and sub-levels.
3. Promise libraries help solve callback hell situations by chaining callbacks and dealing with errors.

[Hirbed]

1 .Synchronous way: It waits for each operation to complete, after that only it executes the next operation. … Asynchronous way: It never waits for each operation to complete, rather it executes all operations in the first GO only

2. When you have to deal with a callback that’s in another callback that’s in yet another callback, especially in nested loops

3. Synchronous calls

[johal]

1. An asynchronous function can be put on hold while another function is started. Synchronous functions start and complete in a sequence. In an asynchronous function, the JavaScript engine creates an additional background thread to start another task while the first task is running. An asynchronous command prevents the browser from locking up.
2. Callback hell may occur when there are several nested function or several sub-level functions running.
3. Using ‘promises’ can reduce callback hell which is a built in JQuery library. The promises library allows functions to be written as though sub-level functions were running synchronously.

[Albin]

1. Synchronous - Occupies the engine until finished
   Asynchronous - Can be initiated and then put aside

2. When we reach a certain level of complexity, there can be numerous nested functions, levels and sub-levels. This is referred to as callback hell

3. Promises

[BillyBule]

1. JS is a single-threaded language, only one section of code can be running at any one time.
   These tasks are called blocking or synchronous.
   An asynchronous task can be initiated and then put aside until a later date while executing another task.

2. Complexity increases as we have more and more nested functions and call backs. This is called callback hell as code can be difficult to understand and debug.

3. 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.

[Depth-Hoar]

1. Synchronous function can only run one section of code at a time.
   asynchronous functions can run multiple sections of code at any one time

2. callbacks within callbacks within callbacks and so on. The code starts to look very messy

3. Promises or libraries

[Dora]

1. Synchronous functions will be executed one after the other, the next function doesn’t begin till the previous one is finished.
   Asynchronous functions can be initiated and than put aside until a later date while a valet gets started on the next task on his to do list.
2. Complex operations tend to produce levels and sub levels, nested functions or callback hell.
3. Technique called Promises can be used. jQuery, AngularJS ship with a simple built-in promise library.

[Adam]

1 asynchronous operations do not need to wait for the last one t o complete, as opposed to synchronous operations only executing after the previous operation completes.
2 This is when arguments are nested together and wait for each to be exececuted,
3 Promise and libraries such as node.js

[Dskeur91]

1. Synchronous => 1 function at a time, asynchronous => multiple functions at 1 time there it is possible to start a new function while another one is doing his thing.

2. The many callback you have with asynchronous functions. The complexity of a programm rises.

3. Promises

[frivolous]

1.What is the difference between synchronous and asynchronous functions?
synchronous - one function at a time
asynchronous - many functions at one time
2.What is callback hell?
-in waiting for the called events to happen at different levels.
Тhere is a possibility of errors.
3.Which technique can help us solve callback hell?
еembedded promises in the library .jQuery , enable us to chain callbacks and deal with errors.
But in Node.js we can use setTimeOut

[Pellerin]

i. What is the difference between synchronous and asynchronous functions? Synchronous (blocking) functions run in real-time. Asynchronous functions (non-blocking) functions can take an unknown amount of time. A website cannot wait for those functions to complete.

ii. What is callback hell? Callback hell is a condition where the number of nested functions is excessive. Complex operations tend to produce even more levels and sublevels.

iii. Which technique can help us solve callback hell? Promises: What is a promise?

iv. The core idea behind promises is that a promise represents the result of an asynchronous operation. A promise is in one of three different states:

1. pending - The initial state of a promise.
2. fulfilled - The state of a promise representing a successful operation.
3. rejected - The state of a promise representing a failed operation.

Once a promise is fulfilled or rejected, it is immutable (i.e. it can never change again).

Another method is Node.js. Node.js extends the runtime, abstracting away the asynchronicity and write code that looks sychronous.

[abnrgr99]

1. Synchronous is a single-threaded environment, only one section of code can be running at any one time.
   Asynchronous tasks can be initiated and then put aside until later.

2. On the server, the Node.js runtime is single-threaded.
   So that, even relatively simple operations that can have several levels of nested functions,
   more complex operations tend to produce even more levels and sub-levels,
   creating a pattern of excessive callbacks.

3. Promises. jQuery has a simple built-in promise library that enables it to chain callbacks and deal with errors.
   By extending the runtime, we can abstract away the asynchronicity and write code that looks sychronous.

[Adi]

1. Synchronous functions - Only one section of the code in the function can run at a time.
   Asynchronous functions - More than one section of the code in the function can run at a time

2)Callback hell is a situation where several functions are being performed in nested form.

3)Promise is used to solve the call back hell situation. jQuery, AngularJS come with promise library. It also handles errors

[CryptoLee6]

1. • Synchronous functions - Only one section of the code in the function can run at any one time.
   • Asynchronous functions - More than one section of the code in the function can run at any one time.
2. When the code includes many callbacks within callbacks and so on.
3. Promises