ES6 conditional statements are used to perform different actions based on various conditions. The conditional statement evaluates a condition before the execution of instructions.
When you write the code, you require to perform different actions for different decisions. You can easily perform it by using conditional statements.
Types of Conditional Statements
- if statement
- if….else statement
- if….else if….statement
- nested if statement
- switch statement
Let us try to elaborate on these conditional statements.
The if statement
If the condition evaluates to true, the code within if statement will execute, but if the condition evaluates to false, then the code after the end of if statement (after the closing of curly braces) will execute.
x is greater
The if….else statement
If the condition is true, then the statements inside if block will be executed, but if the condition is false, then the statements of the else block will be executed.
Let us try to understand if….else statement by the following example:
x is greater
The if….else if…..else statement
It is used to test multiple conditions. The if statement can have multiple or zero else if statements and they must be used before using the else statement. You should always be kept in mind that the else statement must come after the else if statements.
c is greater
The nested if statement
It is an if statement inside an if statement.
20 is greater than 10 and even number After nested if statement
The switch statement
It is a multi-way branch statement that is also used for decision-making purposes. In some cases, the switch statement is more convenient than if-else statements. It is mainly used when all branches depend upon the value of a single variable. It executes a block of code depending upon the different cases.
The switch statement uses the break or default keywords, but both of them are optional. Let us define these two keywords:
break: It is used within the switch statement for terminating the sequence of a statement. It is optional to use. If it gets omitted, then the execution will continue on each statement. When it is used, then it will stop the execution within the block.
default: It specifies some code to run when there is no case match. There can be only a single default keyword in a switch. It is also optional, but it is recommended to use it as it takes care of unexpected cases.
If the condition passed to switch doesn’t match with any value in cases, then the statement under the default will get executed.
Some points to remember
- There can be one or multiple case values for a switch expression.
- The use of break and default keywords are optional.
- The case statements can only include constants and literals. It cannot be an expression or a variable.
- Unless you put a break after the code of every block, the execution will continuously flow into the next block.
- It is not necessary that the default case has to be placed at last in a switch block.