Switch Case - Fullstackadda

The switch case statement is a conditional statement like if else statement. If you want to execute one of the multiple code blocks than Switch is useful.

switch statement is used to execute one code from multiple expressions.

switch(expression) {

case n:

  //code block

break;

case n:

  //code block

break;

default:

  //default code block

}

Break Statement : In switch case, break statement is used so that next conditions won’t be checked after finding the required condition.

What is default value ?

Default in a switch statement is used to group all other values that are not specified that come into it, instead of having to specify all of them. You don’t need a default statement, as long as you know all the values that you will encounter in the variable that the switch statement is considering.

Example:

let day = 5;

switch (day) {
  case 0:
    day = "Sunday";
    break;
  case 1:
    day = "Monday";
    break;
  case 2:
     day = "Tuesday";
    break;
  case 3:
    day = "Wednesday";
    break;
  case 4:
    day = "Thursday";
    break;
  case 5:
    day = "Friday";
    break;
  case 6:
    day = "Saturday";
}

console.log(`Today is ${day}`)

Today is Friday

In the above program, an expression day = 5 is evaluated with a switch statement.

The expression’s result is evaluated with case 1 which results in false.
Then the switch statement goes to the 2nd case. which results in false.
Then the switch statement goes to the 3rd case. which results in false.
Then the switch statement goes to the 4th case. which results in false.
Then the switch statement goes to the 5th case. The expression’s result matches with case 5. So the value “Today is Friday“ is is displayed.
The break statement terminates the block and control flow of the program jumps to outside of the switch block.

Example 2:

let x = 20;

switch (x) {
    case 1:
        x = 'one';
        break;
    case 2:
        x = 'two';
        break;

    default:
        x = 'Not found';
        break;
}
console.log(x);

Not found

Switch vs if…else

Switch case	If else
It has more readable syntax	It has less readable syntax
Multiple cases can be processed if we remove the break statement	Multiple if blocks can not be processed unless each condition is true
It works fast for large values because the compiler creates a jump table	It is relatively slow for large values
It’s input is an expression that can be an enumerated value of a string object	Its input is an expression that can be a specific condition or a range

The switch case statement executes a block of code depending on different cases.
Break statement is used so that next conditions won’t be checked after finding the required condition.