Conditional Statements

Conditional statements are used to perform different actions based on different conditions.

if Statement

Use if to specify a block of code to be executed, if a specified condition is true.

Syntax:

if (condition) {
  //  block of code to be executed if the condition is true.
}

else Statement

Use else to specify a block of code to be executed, if the same condition is false.

Syntax:

if (condition) {
  //  block of code to be executed if the condition is true.
} else {
  //  block of code to be executed if the condition is false.
}

else if Statement

Use else if to specify a new condition to test, if the first condition is false.

Syntax:

if (condition1) {
  //  block of code to be executed if condition1 is true.
} else if (condition2) {
  //  block of code to be executed if the condition1 is false and condition2 is true.
} else {
  //  block of code to be executed if the condition1 is false and condition2 is false.
}

switch Statement

Use switch to specify many alternative blocks of code to be executed.

Syntax:

switch(expression) {
  case x:
    // code block
    break;
  case y:
    // code block
    break;
  default:
    // code block
}

Loops

Loops can execute a block of code a number of times.

for loop

for - loops through a block of code a number of times.

Syntax

for (statement 1; statement 2; statement 3) {
  // code block to be executed.
}

Statement 1 is executed (one time) before the execution of the code block.

Statement 2 defines the condition for executing the code block.

Statement 3 is executed (every time) after the code block has been executed.

for in loop

for/in - loops through the properties of an object.

Syntax

for (key in object) {
  // code block to be executed.
}

for of loop

for/of - loops through the values of an iterable object.

Syntax

for (variable of iterable) {
  // code block to be executed.
}

while loop

while - loops through a block of code while a specified condition is true.

Syntax

while (condition) {
  // code block to be executed.
}

do while loop

do/while - also loops through a block of code while a specified condition is true.

Syntax

do {
  // code block to be executed.
}
while (condition);