Switch Case command in JavaScript

You can use multiple if . else . if statements as in the previous post to make a branch of multiple choices. However, it is not always the best solution, especially when all branches depend on the value of a single variable.

Starting with JavaScript 1.2, you can use a switch command to correctly handle this situation, and it's actually more efficient than repeating if . else if statements .

Implementation diagram

The following diagram explains the switch-case command to work:

Syntax

The goal of a switch command is to provide an expression to estimate and several different commands to execute on the value of the expression. The interpreter checks each case - the case with the value of the expression until a match is found. If there is no match, a default condition - will be used by default .

 switch ( expression ) { case condition 1 : statement ( s ) break ; case condition 2 : statement ( s ) break ; . case condition n : statement ( s ) break ; default : statement ( s ) } 

Break command instructs the end of each specific case. If they are omitted, the interpreter will continue to execute each instruction in each of the following cases.

We will discuss the break command in the Loop control chapter.

For example

Try the following example to execute the switch-case command

  type = "text/javascript" >  

 Set the variable to different value and then try. 

Result:

 Entering block switch 
 Good job 
 Block Exiting switch 
 Đặt biến vào giá trị khác nhau và thử thử . 

Break commands play an important role in switch-case commands. Try the following code using the switch-case command without any break commands.

  type = "text/javascript" >  

 Set the variable to different value and then try. 

Result:

 Entering block switch 
 Good job 
 Pretty good 
 Passed 
 Not so good 
 Failed 
 Unknown grade 
 Block Exiting switch 
 Đặt biến vào giá trị khác nhau và thử thử . 

According to Tutorialspoint

Previous lesson: if . else command in JavaScript

Next: The while loop in JavaScript