async-calls

[mariailoaie]

Added some async calls examples

[ilazar]

As vrea sa folosim arrow functions.

Eu prezint aceste subiecte in general asa:

1. setTimeout(fn, timeout), setTimeout(fn, 0), event queue

2. callbacks

Definesc o fn

const task = ({ name, duration }, callback) => setTimeout(() => {
  if (duration > 100) { // max duration
    callback(new Error(`${name} timeout error`));
  }  else {
   callback(null, name);
  }
}, duration);

si apoi discut

• chaining: a then b (if a fails, then b should not be executed)
• callback hell: a then b then c (if any fails, the next tasks should not be executed)
• parallel execution: a & b in parallel, then c (if one of a or b fails, the other should be cancelled and c should not execute)
• cancellation techniques

3. promises

• refactor task using promises
• the same topics discussed for callbacks

4. async-await

• refactor task using async await
• the same topics discussed for callbacks & async-await

[mariailoaie]

Ok, o sa fac modificarile