Ternary operator / Question mark and colon in JavaScript

“Question mark” or “conditional” operator in JavaScript is a ternary operator that has three operands.

  • The expression consists of three operands: the condition, value if true and value if false.
  • The evaluation of the condition should result in either true/false or a boolean value.
  • The true value lies between “?” & “:” and is executed if the condition returns true. Similarly, the false value lies after “:” and is executed if the condition returns false.

Syntax:

condition ? value if true : value if false
    condition:

  • Expression to be evaluated which returns a boolean value.
  • value if true:

  • Value to be executed if condition results in true state.
  • value if false:

  • Value to be executed if condition results in false state.

Examples:

Input: let result = (10 > 0) ? true : false;
Output: true

Input: let message = (20 > 15) ? "Yes" : "No";
Output: Yes

The following programs will illustrate conditional operator more extensively:

Program 1:

filter_none

edit
close

play_arrow

link
brightness_4
code

<script>
    //JavaScript to illustrate
    //Conditional operator
  
    let age = 60
    let result = (age > 59)?
        "Senior Citizen":"Not a Senior Citizen"
  
    alert(result);
</script>                    

chevron_right


Output:

Senior Citizen

An example of multiple conditional operators.
Program 2:

filter_none

edit
close

play_arrow

link
brightness_4
code

<script>
    //JavaScript to illustrate
    //multiple Conditional operators
  
    let marks = 95;
    let result = (marks < 40) ? "Unsatisfactory"
             (marks < 60) ? "Average" :
             (marks < 80) ? "Good" : "Excellent" ;
  
    alert(result);
</script>        

chevron_right


Output:

Excellent


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.