Control and looping structure in javascript

1. If  Statement

• IF statement is a conditional branching statement.
• In 'IF' statement, if the condition is true a group of statement is executed. And if the condition is false, the following statement is skipped.

Syntax : If statement

if(condition)
{
     //Statement 1;
     //Statement 2;
}

Example : Simple Program for IF Statement

Output:

2. If – Else Statement

• If – Else is a two-way decision statement.
• It is used to make decisions and execute statements conditionally.

Flow Diagram of If – Else Statement

Syntax : If-Else statement

if (condition)
{
     //Statement 1;
}
else if(condition)
{
     //Statement 2;
}
else
{
     //Statement 3;
}

Example : Simple Program for If-Else Statement

Output:

3. Switch Statement

• Switch is used to perform different actions on different conditions.
• It is used to compare the same expression to several different values.

Flow Diagram of Switch Statement

Syntax

switch(expression)
{
     case condition 1:
          //Statements;
          break;
     case condition 2:
          //Statements;
          break;
     case condition 3:
          //Statements;
          break;
     .
     .
     case condition n:
          //Statements;
          break;
     default:
          //Statement;
}

Example : Simple Program for Switch Statement

Output:

4. For Loop

• For loop is a compact form of looping.

It includes three important parts:
1. Loop Initialization
2. Test Condition
3. Iteration
• All these three parts come in a single line separated by semicolons(;).

Flow Diagram of 'For' Loop

Syntax

for(initialization; test-condition; increment/decrement)
{
     //Statements;
}

Example : Palindrome Program using For Loop

Output:

5. For-in Loop

• For-in loop is used to traverse all the properties of an object.
• It is designed for looping through arrays.

Syntax

for (variable_name in Object)
{
     //Statements;
}

6. While Loop

• While loop is an entry-controlled loop statement.
• It is the most basic loop in JavaScript.
• It executes a statement repeatedly as long as expression is true.
• Once the expression becomes false, the loop terminates.

Flow Diagram of While Loop

Syntax

while (condition)
{
     //Statements;
}

Example : Fibonacci Series Program using While Loop

Output:

7. Do-While Loop

• Do-While loop is an exit-controlled loop statement.
• Similar to the While loop, the only difference is condition will be checked at the end of the loop.
• The loop is executed at least once, even if the condition is false.

Flow Diagram of Do – While

Syntax

do
{
     //Statements;
}
while(condition);

Example : Simple Program on Do-While Loop

Output:
0
1
2
3
4
5

Difference between While Loop and Do – While Loop

8. Break Statement

• Break statement is used to jump out of a loop.
• It is used to exit a loop early, breaking out of the enclosing curly braces.

Syntax:
break;

Flow Diagram of Break Statement

9. Continue Statement

• Continue statement causes the loop to continue with the next iteration.
• It skips the remaining code block.

Flow Diagram of Continue Statement

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