promise

JavaScript - Promise

Promise is an object in javascript where it can resolve or reject the asynchronous operation.

It is a syntactical coating introduced by ES6 to escape from the callback hell.

It provides .then() to handle resolve and .catch() to handle reject operations.

• Example of promise

  const hasRightToVote = (age) => {
      return new Promise((resolve, reject) => {
          // statements
          resolve("You can vote!")
          reject("Please enter valid age!");
      });
  };
  
  hasRightToVote(120).then(data => {
      // statements
  }).catch((error) => {
      // statements
  })

• We can use async/await to avoid .then() callback.