APIs

console.log("first line");

setTimeout(() => {

console.log("second line");

}, 3000);

console.log("third line");

What will be the correct order of output?

• first line → second line → third line

• first line → third line → second line

• second line → first line → third line

• third line → first line → second line

let x = new XMLHttpRequest();

x.open("GET", "https://jsonplaceholder.typicode.com/posts");

x.send();

x.addEventListener("load", function(){

console.log(x.responseText);

});

Which statement is correct?

• This code runs synchronously

• console.log(x.responseText) will run only after the data is fully loaded

• console.log will never run

• x.send() blocks the code until data is received

Why is callback() used ?

• To delay sending the request

• To run code after the data is fetched

• To repeat the request multiple times

• To convert data to JSON

console.log("first line");

setTimeout(() => { console.log("second line"); }, 3000);

setTimeout(() => { console.log("one"); }, 5000);

setTimeout(() => { console.log("two"); }, 2000);

console.log("third line");

What is the correct output order?

• first line → third line → two → second line → one

• first line → second line → two → third line → one

• third line → first line → one → two → second line

• first line → third line → second line → one → two

function a(){

console.log("a");

a();

}

a();

What will happen when this code runs?

• It prints "a" once only

• It prints "a" multiple times then stops after 5 times

• Maximum call stack size exceeded error

• Nothing will be printed

What is the purpose of the resolve() and reject() functions in the following promise?

• resolve() logs the response, and reject() retries the request.

• resolve() marks the promise as successful (proceeding to .then()), and reject() triggers .catch().

• Both resolve() and reject() terminate the promise chain.

• They are optional and have no effect on the promise.

What is wrong with the following callback-based code compared to the promise version?

• It uses fewer API calls.

• It suffers from "callback hell" (nested, hard-to-read code)

• It runs faster than the promise version.

• It logs responses more clearly.

What is missing in the promise's error handler?

x.addEventListener("error", function() {

console.log("Failed to load pizza data");

// Missing something here?

});

• resolve()

• reject()

• Nothing—it’s complete.

getPizza(function(){

getPasta(function(){

console.log("Done");

});

});

What is the correct execution order?

• Done → pizzaaa → pastaa

• pizzaaa → pastaa → Done

• pastaa → pizzaaa → Done

• pizzaaa → Done → pastaa

What does this do?

x.responseType = "json";

• Converts the response to text

• Sends the request in JSON format

• Automatically parses the response as JSON

• Prevents the request from loading