reading-notes

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Node Ecosystem, TDD, CI/CD

Array.map()

• It is an array method that is used to iterate over an array and that is used to returns a new array and elements of the original arrays are result of callback function.
  • return new array
  • need a return
  • This method accepts two parameters

Array.reduce()

• It is an array method that is executes a reducer function for each value of an array.
  • does not change the original array.
  • returns a single value which is the function’s accumulated result.
  • need a return

superagent()

• With normal Promise .then() syntax:

• With async / await syntax

promises

• Promises, wrapping the asynchronous operation result, can be returned synchronously from a function, assigned to variables, or used as arguments. That’s the idea of promises: encapsulate the asynchronicity and allow function handling asynchronous operations to still look synchronous.
• A promise is an object that encapsulates the result of an asynchronous operation.

• Each promise has state, which can have one of the following values:

  • Pending
  • Fullfilled with a value
  • Rejected for a reason

Are all callback functions considered to be Asynchronous? Why or Why Not?

• No,Simply taking a callback doesn’t make a function asynchronous. There are many examples of functions that take a function argument but are not asynchronous. For example there’s forEach in Array. It iterates over each item and calls the function once per item.

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References:

@By Dmitri Pavlutin/What is a Promise in JavaScript?

@By PANU PITKAMAKI/Does taking a callback make a function asynchronous?