Javascript-Conditional Statements

Conditional statements (1).png

A conditional statement is a series of instructions that are considered true when specific conditions are met. When writing code, we want to be able to take various actions depending on the circumstances without having to define a new set of conditions everytime, this is accomplished in programming using conditional statements. These statements have many applications, and computer programmers frequently use them to verify assumptions and create rules that programs must abide by.

The following are some examples of conditional statements in javascript:

"if" statement
"else" statement
"else if" statement
Switch statement

The "if" statement

This is a conditional statement that will perform the specified action in the event that the given condition is true. There must be a clear condition before a given action can be executed if it is met.

The syntax of "if" statement:

if 1.png

To write an "if" statement:

Establish a variable.
Put the necessary conditions in brackets.
Activate a curly bracket
Indicate what should happen if the condition is true or met.
Close the curly bracket

Example:

if 2.png

In the above example,

The variable is examScore

The condition is that if examScore is less than or equal to 39, you want the user to see "You failed. Try again next semester" on the screen.

The above result translates to below when you open with lifesaver:

if 3.png

If you input any number less than or equal to 39 which makes the condition true, you get the alert below:

if 4 replaced.png

The "else" statement

else statement is used to perform an alternative action if the same condition specified earlier is false. The statement allows another action to occur without declaring a second condition.

"else" statement syntax:

else 1.png

To write an "else" statement:

Declare a variable
Specify condition to be met in a bracket
Open a curly bracket
State the action to be performed if condition is true/met
Close the curly bracket
State else
Open another curly bracket
State action to be performed if condition is false/not met
Close the second curly bracket

Example: using the same example used in if statement

else 2.png

This example produces the same result as seen in the if statement as long as the condition remains true. But if the examScore is greater than 39, a different message is displayed. In this case,it is "congratulations! You passed" as seen below.

else 3.png

The "else if" statement

This conditional statement is used to specify a completely new condition to be tested if the first condition is false. In this situation, the program tests the first condition and if it is not met, it tests the second condition which is the else if condition to see if it is true. It then displays results accordingly.

"else if statement syntax:

else if 1.png

To write an "else if" statement:

Declare a variable
Specify the first condition to be met in a bracket
Open a curly bracket
State the action to be performed if condition 1 is true/met
Close the curly bracket
State else if
Specify condition 2
Open curly bracket
State action to be perform if condition 1 is false but condition 2 is true
Close curly bracket
State else
Open another curly bracket
State action to be perfomed if both condition 1 and condition 2 is false/not met
Close curly bracket

Example: same as before

else if 2.png

This example produces the three (3) results below:

If condition 1 is true

else if 3.png

if condition 1 is false but condition 2 is true

else if 4.png

if both condition 1 and condition 2 is false

else if 5.png

The "switch" statement

A switch statement serves as a substitute for the "else if" statement preferably in cases that involves more than 3 conditions. In this type of conditional statement, a switch expression is stated, the value of the expression is compared with the value of each case, if the value is the same, the associated action is executed. If there is no match, the action in the default code block is executed.

switch statement syntax:

switch 1.png

The "break" keyword

When the program reaches the keyword, it breaks out of the switch block, this stops the execution of action in the switch block. If the break statement is omitted, the next case will be executed even if the value doesn't match the expression.

The "default" keyword

The default keyword specifies the action to perform if no case matches the value of the expression. Example: same as before

switch 2.png

There are 6 cases and actions in the above example (5 cases and a default case).

The switch statement produces a neater code than the else if statement, and the result of the above program is shown below.

If examScore is less than or equal to 39

If examScore is greater than 44 and less than or equal to 49

switch 4.png

If examScore is greater than 49 and less than or equal to 59

switch 5.png

If examScore is greater than 59 and less than or equal to 69

switch 6.png

If examScore is greater than or equal to 70

switch 7.png

If none of the cases matches the value of the expression

switch 8.png

Please keep in mind that this is an attempt to demonstrate my knowledge of Mr Kenny's Javascript Conditional Statement class. If you are new to the world of software development and find this useful, please click the like button. If you are an expert in the field, please share your thoughts.

Keep an eye out for my future piece.

Thank You

Tekherbalist

CONDITIONAL STATEMENTS - Javascript

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