Execution Stack

(Call Stack)

A JavaScript engine – V8 – is a program or interpreter that executes JavaScript code. It is used in Chrome and Node.js.

// Sync
function f1( ) {
  console.log('One')
}

function f2( ) {
  console.log('Two')
  f1( );
}

function f3( ) {
  console.log('Three')
  f2( );
}

// Invoke
f3( );

//Output: Three Two One 

// Async 
function f1(){
  console.log("Hello")
}

function f2(){
  console.log("Goodbye")
  setTimeout(f1, 0); //callback
}

function f3(){
  let x = new Promise((resolve, reject) => {
  resolve("Thanks"); 
  reject("Error");
    })
// Comsumer .then 
x.then(result => console.log(result), error => console.log(error) );
  f2();
  return x;
}

// Invoke
f3();

//Output: Goodbye Thanks Hello

function f1() {
  console.log('One');
}

function f2() {
  console.log('Two');
  setTimeout(f1, 1000); // This will call f1 after 1 second
}

function f3() {
  new Promise((res, rej) => {
      res('Three');
      // No need for rej here since the promise is always resolved
  })
  .then(x => { console.log(x); })
  .catch(e => { console.log(e); });
}

f2();
f3();

//Output: Two Three One

function f1() {
  console.log("Hello!");
}
function f2() {
    setTimeout((f2)=>{console.log("Goodbye!");}, 1000)
    f1();
  };
function f3() {
  f2();
  new Promise((resolve, reject)=>{
    let x = false;
    if(x){
        resolve("Thank you!")
    }else {
        reject("Error")
    }
  })
  .then((message) => {console.log(message)})
  .catch((error) => {console.log(error)})
  .finally(()=> {console.log("See you again!")})
}
f3();

//Output: Hello Error See you again! Goodbye!

function createPromise(message) {
  return new Promise((resolve, reject) => {
    resolve(message);
  })
  .then(result => {
    console.log(result);
  })
  .catch(error => {
    console.log(error);
  });
}

function f1(){
  createPromise("Hello");
}

function f2(){
  createPromise("Goodbye");
  setTimeout(f1, 0);
}

function f3(){
  createPromise("Thanks");
  f2();
}

f3();

//Output: Thanks Goodbye Hello

function selectFruit(callback) {
  setTimeout(() => {
    console.log("Selected fruit");
    callback();
  }, 1000);
}

function chopFruit(callback) {
  setTimeout(() => {
    console.log("Chopped fruit");
    callback();
  }, 1000);
}

function processOrder() {
  selectFruit(() => {
    chopFruit(() => {
      console.log("Order processed");
    });
  });
}

processOrder();

//Output: Selected Fruit, 
//        Chopped Fruit, Order Processed

function selectFruit() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("Selected fruit");
      resolve();
    }, 1000);
  });
}

function chopFruit() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("Chopped fruit");
      resolve();
    }, 1000);
  });
}

function processOrder() {
  selectFruit()
    .then(chopFruit)
    .then(() => {
      console.log("Order processed");
    })
    .catch((error) => {
      console.log("Error:", error);
    });
}

processOrder();

//Output: Selected Fruit, 
//        Chopped Fruit, Order Processed

function selectFruit() {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log("Selected fruit");
      resolve();
    }, 1000);
  });
}

function chopFruit() {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log("Chopped fruit");
      // Example of an error condition
      reject("Error in chopping fruit");
    }, 1000);
  });
}

function processOrder() {
  selectFruit()
    .then(chopFruit)
    .then(() => {
      console.log("Order processed");
    })
    .catch((error) => {
      console.log("Error:", error);
    });
}

processOrder();

//Output: Selected Fruit, 
//        Chopped Fruit, Error