JavaScript if not | Example code

JavaScript if not used with non-Boolean values, it returns false if its single operand can be converted to true.

Use the Logical NOT ! operator:

if(!condition){
    expression();
}

JavaScript if not an example

simple example code.

<!DOCTYPE html>
<html>
<body>
  <script>

    var isDay = false;
    if (!isDay) { 
      console.log("It's night");
    }
  </script>
</body>
</html>

Output:

How to check if a variable is not null?

Answer: Here is how you can test if a variable is not NULL:

if (myVar !== null) {...}

the block will be executed if myVar is not null.. it will be executed if myVar is undefined or false or 0 or NaN or anything else.

Read more: JavaScript isNull

Do comment if you have any doubts or suggestions on this JS if topic.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version

JavaScript if not | Example code

JavaScript if not an example

How to check if a variable is not null?

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