Loops and Iteration

Question 1

Why are there various loop mechanisms?

Answer 1

Various loops offer you different ways to determine the start and end points of the loop.

Question 2

What are the 8 statements for loops provided in Javascript?

Answer 2

1. for
2. do…while
3. while
4. labeled
5. break
6. continue
7. for…in
8. for…of

Question 3

What is the ‘for’ loop?

Answer 3

A loop that repeats until a specified condition evaluates to false.

Question 4

Write down the ‘for’ loop syntax.

Answer 4

for(initialExpression; condition; incrementExpression){
// block of code;
}

Question 5

What is the ‘do…while’ loop?

Answer 5

A loop that repeats until a specified condition evaluates to false.

Question 6

Write down the ‘do…while’ loop.

Answer 6

do {
   //block of code;
} while (condition);

Question 7

In the ‘do…while’ loop, the statement (block of code) is executed ___ before the condition is checked. Execution stops when the statement is _____.

Answer 7

once. false.

Question 8

What is the ‘while’ loop?

Answer 8

A loop that executes its statement as long as the specified condition evaluates to true.

Question 9

Write down the syntax for the ‘while’ loop?

Answer 9

while (condition is true) {
run//block of code;
}

Question 10

What is the ‘label’ loop?

Answer 10

A loop that provides a statement with an identifier that lets you refer to it elsewhere in your program. It’s basically creating a nameSpace for a loop statement.

Question 11

Write down the syntax for the ‘label’ loop.

Answer 11

label:
statement {
}

eg.) markLoop:
while (theMark == true) {
doSomething();
}

Question 12

What is the ‘break’ statement?

Answer 12

Terminates a loop, ‘switch’, or in a ‘labelled’ statement.

Question 13

Write down the syntax for the ‘break’ statement.

Answer 13

break;

or with conjunction with the ‘label’ statement:
break([label]);

Question 14

What is the ‘continue’ statement?

Answer 14

Used to restart a while, do…while, for, or label statements.

Question 15

The continue statement will jump back to the condition of a ____ loop. In a ___ loop, it jumps to the increment-expression.

Answer 15

while. for.

Question 16

What is the ‘for…in’ loop?

Answer 16

Iterates a specified variable over all the enumerable properties of an object. For each distinct property, JavaScript executes the specified statements.

Question 17

Write down the syntax for the ‘for…in’ loop?

Answer 17

for (variable in object) {
     //block of code
}

Question 18

What is the ‘for…of’ statement?

Answer 18

Creates a loop iterating over iterable objects (including array, map, set, arguments objects) invoking a custom iteration hook with statements to be executed for the value of each distinct property.

Question 19

Write the syntax for the ‘for…of’ loop.

Answer 19

for (variable of object) {
      // block of code
}

Question 20

What is the difference between a ‘for…in’ loop and a ‘for…of’ loop?

Answer 20

A ‘for…in’ loop iterates over property names(keys).

A ‘for…of’ loop iterates over property values.