Checkpoints 08 - JavaScript Callbacks

1번 - After running the following code, what will be the value of result?

function doubleUp (f, x) {
return f( f(x) );
};

function subject (value) {
return value + "!";
};

var result = doubleUp(subject, "hi");

1번 질문의 답을 선택하세요. *

"hi"

"hi!"

"hi!!"

"hi!!!!"

 

2번 - After running the following code, what will be the value of result? (You may look up JavaScript ternary operator if you need to.)

function eitherOne (f, g, x) {
return (x % 2 === 0) ? f(x) : g(x);
};

var result = eitherOne(
function (x) { return x + 5 },
function (x) { return x - 5 },
15
)

2번 질문의 답을 선택하세요. *

5

10

15

20

30

3번 - After running the following code and all setTimeouts have run their callbacks, what will be the value of result?

 

var result = 10;

function wait (time, f) {
setTimeout(function () {
result = f(result);
}, time);
}

wait(500, function (x) { return x + 5 })
wait(250, function (x) { return x * 2 })

3번 질문의 답을 선택하세요. *

0점

 

10

 

15

 

20

 

25

 

30

4번 - Using the concept of callbacks, write the exercise function so that result will equal 42.

 

function exercise (???) {
???
}

var a = exercise(10, function (x) {
return x + 2;
});

var b = exercise(15, function (x) {
return x * 2;
});

var result = a + b;

4번 질문의 답을 적어주세요. *

0점

내 답변

 

 

5번 - After the following code runs, what will be the value of result?

 

function foo () {

var data = 10;

bar(function (players) {
data = players;
});

return data;
}

function bar (callback) {
callback(20);
}

var result = foo();

5번 질문의 답을 선택하세요. *

0점

 

10

 

20

 

undefined

6번 - After the following code runs and all setTimeout callbacks run, what will be the value of result?

 

function foo () {

var data = 10;

bar(function (players) {
data = players;
});

return data;
}

function bar (callback) {
setTimeout(function () {
callback(20);
}, 500); // 리턴 이후 20초후에 20으로 데이터 값 변경
}

var result = foo();

6번 질문의 답을 선택하세요. *

0점

 

10

 

20

 

undefined

7번 - After the following code runs and all setTimeout callbacks run, what will be the value of result?

function foo () {

var data = 10;

bar(function (players) {
data = players;
});

return data;
}

function bar (callback) {
setTimeout(callback, 0);
}

var result = foo();

7번 질문의 답을 선택하세요. *

0점

10

20

undefined