TypeScript - Switch Case Statement

Introduction

The switch statement is used to perform multiple possible conditions by comparing an expression to different values. It is often preferred over multiple if-else statements when comparing a single variable against many possible values.

Syntax:

switch (expression) {
  case value1:
    // Code to execute if expression equals value1
    break;
  case value2:
    // Code to execute if expression equals value2
    break;
  // More cases can follow
  default:
    // Code to execute if no case matches
}

The expression is evaluated once.
The value of the expression is compared with each case value.
If a match is found, the corresponding code block is executed.
The break statement is used to exit the switch statement once a match is found.
The default block is executed if no cases match the expression.

Example 1: Basic Switch Case

let day = 2;
 
switch (day) {
  case 1:
    console.log("Monday");
    break;
  case 2:
    console.log("Tuesday");
    break;
  case 3:
    console.log("Wednesday");
    break;
  default:
    console.log("Invalid day");
}

Output:

Tuesday

Example 2: Switch Case with Multiple Matches

let fruit = "apple";
 
switch (fruit) {
  case "apple":
    console.log("This is an apple.");
    break;
  case "banana":
    console.log("This is a banana.");
    break;
  case "orange":
    console.log("This is an orange.");
    break;
  default:
    console.log("Unknown fruit");
}

Output:

This is an apple.

Example 3: Switch Case Without Break

let score = 85;
 
switch (score) {
  case 90:
  case 85:
    console.log("Grade B");
    break;
  case 80:
    console.log("Grade C");
    break;
  default:
    console.log("Grade D");
}

Output:

Grade B

Conclusion

The switch statement is a powerful control structure in TypeScript that simplifies checking multiple possible values for a single expression. It is useful when comparing a variable against several values and helps avoid multiple if-else statements.

If Else Statement Loops