//! Asynchrononous javascript
//! synchrononous:
/*
console.log(“First”); //First
console.log(“Second”); //Second
console.log(“Third”); //Third
task contionue vaa poittea irukkum
*/
//! Asynchrononous:
/*
console.log(“Hello World.!”); // 1st print aagum
setTimeout(() => {
console.log(“Hello after 2 seconds”); // 2 sec apram third print agum
}, 2000);
console.log(“welcome ‘javascript'”); // second print aagum
*/
/*
//! callback function
// Callback illustrated
function One() {
// Do something // apram one ulllathu execute agum.
}
function Two(call_One) {
// Do something else
call_One() // one na call pannum
}
Two(One); // two vaa call pannum
//? call back inga aathigam use pannrathu illa.
*/
/*
//! Promises
// !3 states: Pending, Fulfilled, Rejected
// ! Pending: Initial state, not yet started
// ! Fulfilled: Successful, resolved with a value
// ! Rejected: Failed, rejected with a reason
// var name //obj // 2 arguments const myPromise = new Promise((resolve, reject) => {
//false
const error = true; // condition if (!error) { resolve("Yes! resolved the promise");
} else { reject("No! rejected the promise.");
}
})
console.log(myPromise);
//! true output: return states
// Promise : ‘NO! reJECT the promise.’
//! false output: return states
// Promise {: ‘Yes! resolved the promise’
// [[Prototype]]: Promise[[PromiseState]]: “fulfilled”[[PromiseResult]]: “Yes! resolved the promise”
//function
myPromise
.then(value =>{
//console.log(value); // ‘Yes! resolved the promise’
return value + ” welcome”; // ‘Yes! resolved the promise welcome’
})
//! another then another then use pannalamm.
.then(newvalue=> {
console.log(newvalue); // ‘Yes! resolved the promise’ return panna value ingaa vaarum
})
.catch(error =>{
console.log(error); // 'No! rejected the promise.'
});
*/
// !example:
/*
const myPromise = new Promise((resolve, reject) => {
const error = false; if (!error) { resolve("Yes! resolved the promise");
} else { reject("No! rejected the promise.");
}
});
const myNextPromise = new Promise((resolve, reject) => {
setTimeout(function () { resolve("my next promise resolved"); }, 3000)
});
myPromise
.then((value) => {
console.log(value); // ‘Yes! resolved the promise’ return panna value ingaa vaarum
})
myNextPromise.then(value=> {
console.log(value); // ‘Yes! resolved the promise’ return panna value ingaa vaarum
}).catch(error =>{
console.log(error); // 'No! rejected the promise.'
});
*/
//! pending
const users = fetch(“http://jsonplaceholder.typicode.com/users”).then(response =>{
//console.log(response);//Response {type: ‘cors’, url: ‘https://jsonplaceholder.typicode.com/users‘, redirected: true, status: 200, ok: true, …}
return response.json();
}).then(users =>{
console.log(users);
// console.log(users[0].name); // ‘Leanne Graham’
//console.log(users[0].email); // ‘[email protected]‘
//console.log(users[0].address.street); // ‘Kulas Light’
//users.forEach(user => { // for each // console.log(users);
// });
})
console.log(users); // Promise {}
//! Async / Await