js switch case
Explanation of switch case in JavaScript
A switch case statement is a control flow statement in JavaScript that allows you to execute different code blocks based on different conditions. It provides an alternative to using multiple if-else statements.
The syntax of a switch case statement is as follows:
switch (expression) {
case value1:
// code block to be executed if expression matches value1
break;
case value2:
// code block to be executed if expression matches value2
break;
case value3:
// code block to be executed if expression matches value3
break;
default:
// code block to be executed if expression doesn't match any of the cases
}
Here's an explanation of each step involved in a switch case statement:
The
switch
keyword is followed by an expression in parentheses. This expression is evaluated, and its value is compared to the values specified in thecase
statements.The
case
keyword is followed by a value that is compared to the expression. If the expression matches the value, the code block associated with that case is executed.If a match is found, the code block associated with that case is executed. This code block can contain one or more statements.
After executing the code block of a matched case, the
break
statement is used to exit the switch case statement. Without thebreak
statement, the execution would continue to the next case, even if it doesn't match the expression.If none of the cases match the expression, the
default
case is executed (if present). Thedefault
case is optional and is used to specify the code block that should be executed when none of the cases match the expression.After executing the code block of a matched case or the default case, the switch case statement is exited.
It's important to note that the expression in the switch case statement can be of any data type, including numbers, strings, or variables.
Example:
let day = 3;
let dayName;
switch (day) {
case 1:
dayName = "Monday";
break;
case 2:
dayName = "Tuesday";
break;
case 3:
dayName = "Wednesday";
break;
case 4:
dayName = "Thursday";
break;
case 5:
dayName = "Friday";
break;
default:
dayName = "Invalid day";
}
console.log(dayName); // Output: Wednesday
In this example, the value of the day
variable is compared to different cases, and the corresponding dayName
is assigned based on the match. Since day
is 3, the code block associated with the case 3
is executed, and dayName
is set to "Wednesday".