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JavaScript JavaScript Basics (Retired) Making Decisions with Conditional Statements Combining Multiple Tests Into a Single Condition

Posted by Adam Tatusko
Adam Tatusko
16,589 Points

Non-Boolean Variable Truth

In JavaScript, the following code

var answer = 'y';
if (answer) {
  console.log('That is TRUE');
} else {
  console.log('That is FALSE');
}

will indeed write That is TRUE to the console, so it is a valid conditional, even though answer is a String variable and not a Boolean variable.

4 Answers

Cody Coats
Cody Coats
7,469 Points

Yep in javascript Strings are considered truthy except "" which is falsey. This holds even for "0" and "false" both are truthy. Pretty much anything can be evaluated with a conditional in javascript it is not restricted to Booleans.

The falsey values are :

false
0 (zero)
"" (empty string)
null
undefined
NaN (a special Number value meaning Not-a-Number!)

Everything else will be truthy.

Adam Tatusko
Adam Tatusko
16,589 Points
Adam Tatusko
Adam Tatusko
16,589 Points

Good to know. Thanks Cody. You're the man!

kheiferfuller
kheiferfuller
8,635 Points
kheiferfuller
kheiferfuller
8,635 Points

Haha when someone first mentioned the word truthy in relation to JS I couldn't stop laughing. I still can't now. Thanks for the pointer.

Jorge Rodriguez
Jorge Rodriguez
2,599 Points
Jorge Rodriguez
Jorge Rodriguez
2,599 Points

Thanks for the extra tip.