In this tutorial we will learn about JavaScript switch conditional statement.
We use the switch conditional statement to compare a single value with a list of values and execute a piece of code according to a match.
switch
It is a compact version of the nested if/else statement.
Syntax
switch (value) { case val1 : //some code break; case val2 : //some code break; default : //some code }
Alright, lets dive into the details.
We use the switch keyword to create a switch conditional statement. Then inside it we pass a value. This value can be from a variable or result of a expression.
switch ( value ) { }
Inside the switch we have some case block. They have a value followed by : colon. So, the case value is matched with the switch value. If a match is found then the code of that case block is executed.
case
:
We end the case block with the break keyword. This takes us out of the switch.
break
We also have a default which is executed if no match is found. This is optional.
default
In the following example case 3 code will be executed as value of variable x = 3.
var x = 3; switch ( x ) { case 1 : console.log("value of x = 1"); break; case 2 : console.log("value of x = 2"); break; case 3 : console.log("value of x = 3"); break; case 4 : console.log("value of x = 4"); break; default : console.log("value of x something else"); }
Output
value of x = 3
If multiple case value have the same code then we can join them together in order to avoid repeating the same code block.
In the following example case 1 and case 2 share the same code block. Similarly, case 3 and case 4 share the same code block.
var x = 4; switch ( x ) { case 1 : case 2 : console.log("value of x <= 2"); break; case 3 : case 4 : console.log("value of x >= 3 and x <= 4"); break; default : console.log("value of x something else"); }
value of x >= 3 and x <= 4
In the above code value of x matches case 4. In the switch we can see case 3 and case 4 share the same code so, "value of x >= 3 and x <= 4" is printed in the browser console.