JavaScript 101

1. How would you write code to make the ship move forward until it hits an obstacle?

• if (!isObstacle()) {
      forward();
  }
  

• 

  while (!isObstacle()) { 
      forward(); 
  } 
  

• while (isObstacle()) {
      forward(); 
  }
  

• if (isObstacle()) { 
      backward(); 
  }
  

2. What is wrong with this code?

    while (condition) { 
        if (condition) {
            forward();
        }
    }

• You cannot put a conditional in a loop
• There is a redundant check of the condition
• The code will infinitely loop
• Nothing is wrong with the code

3. If the variable i is currently set to 0, what would this code do?

    while (i < 10) {
        print(i);
        i++; 
    } 

• Print out the number 0 once
• Print out the number 0 ten times
• Print out the numbers 1-10
• Print out the numbers 0-9

4. What would the following code do?

    while (true) {
        print(“Hello”);
    }

• Print “Hello” once
• Print “Hello” infinitely
• Do nothing
• None of the above

5. "While" loops always terminate eventually.

• True
• False

6. What is the output of this code?

    var i = 1; 
    while (i < 1) {
        print(“hello”); 
    }

• hello

• hello
  hello
  

• It will output an error
• It won't output anything

7. When might you use a "while" loop instead of a "for" loop?

• If you know exactly how many iterations you want to perform
• If you don’t know exactly how many iterations you want to perform
• You should always use a "while" loop instead of a "for" loop
• You should never use a "while" loop instead of a "for" loop

8. What is the difference between a "while" loop and a "do-while" loop?

• A "while" loop checks the condition at the beginning of each loop, but a "do-while" loop checks the condition at the end of each loop
• A "do-while" loop checks the condition at the beginning of each loop, but a "while" loop checks the condition at the end of each loop
• A "while" loop will always execute the code inside the loop. A "do-while" loop will not
• They are the same and are used interchangeably

9. These two sets of code do the same thing.

        do {
            forward(); 
        } 
        while (path_clear);


        forward();
        while (path_clear) {
            forward();
        }
    

• True
• False

10. When would you use a "do-while" loop?

• When you want to run a loop at least once no matter what
• Whenever you want to do the same thing as a "while" loop
• When running a "while" loop takes too long
• None of the above

11. What would you fill in the blank to make the following code print “hello” 3 times?

    var x = 0;
    do {
        console.log(“hello”);
        x = x + 1; 
    }
    while (x < ___);

• 1
• 2
• 3
• 4

12. The condition is checked at the end of each loop in a "do-while" loop.

• True
• False

13. What is the value of x after the following code is executed?

    var x = 0;
    do {
        x = x + 1;
    } 
    while  (x < 0);

• 0
• 1
• 2
• The code will output an error