1. Introduction
The switch
statement is a control flow statement in JavaScript that allows you to execute different code blocks based on different conditions. It provides a concise way to write multiple if...else
statements and makes the code more readable and maintainable. The switch
statement evaluates an expression and compares it with multiple cases, executing the code block that matches the evaluated value.
2. Syntax
The syntax of the switch
statement is as follows:
javascriptswitch (expression) {
case value1:
// code block executed when expression matches value1
break;
case value2:
// code block executed when expression matches value2
break;
...
case valueN:
// code block executed when expression matches valueN
break;
default:
// code block executed when expression doesn't match any case
break;
}
3. Explanation
- The
switch
statement starts with theswitch
keyword, followed by the expression to be evaluated in parentheses. - Inside the
switch
statement, you define multiplecase
blocks, each representing a possible value that the expression can match. - When the expression matches a
case
value, the code block associated with thatcase
is executed. - The
break
statement is used to terminate theswitch
statement and prevent the execution of subsequentcase
blocks. Without thebreak
statement, the code would continue to execute the followingcase
blocks until abreak
is encountered or theswitch
statement ends. - If none of the
case
values match the expression, the code block within thedefault
case is executed (optional). Thedefault
case serves as a fallback option when no othercase
matches.
4. Example
Let's consider an example that uses the switch
statement to determine the day of the week based on a numerical input:
javascriptfunction getDayOfWeek(dayNumber) {
let day;
switch (dayNumber) {
case 1:
day = "Sunday";
break;
case 2:
day = "Monday";
break;
case 3:
day = "Tuesday";
break;
case 4:
day = "Wednesday";
break;
case 5:
day = "Thursday";
break;
case 6:
day = "Friday";
break;
case 7:
day = "Saturday";
break;
default:
day = "Invalid day";
break;
}
return day;
}
console.log(getDayOfWeek(3)); // Output: "Tuesday"
console.log(getDayOfWeek(8)); // Output: "Invalid day"
In the above example, the getDayOfWeek
function takes a dayNumber
as input and uses a switch
statement to determine the corresponding day of the week. If the dayNumber
matches one of the case
values, the corresponding day is assigned to the day
variable. Otherwise, the default
case is executed, assigning the value "Invalid day" to the day
variable. Finally, the function returns the determined day.
5. Conclusion
The switch
statement in JavaScript provides an efficient way to handle multiple possible values of an expression. By using case
blocks, you can specify different code paths based on the evaluated value, resulting in cleaner and more readable code.
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