Javascript Truthy and falsy examples

Boolean in javascript always evaluates to true or false values.

It uses in boolean expressions such as conditional expressions and equality operators. In Other programming languages, boolean values are true and false .

In Javascript truthy and falsy values are not only true and false, but any data which evaluates to boolean expression.

truthy - return true when resolved to true in boolean context falsy - return false when resolved to false in boolean context

#javascript falsey values examples

falsy values are values that are false during the execution of the boolean expression.

The following are falsy values.

• false
• NAN
• undefined
• null
• zero(0)
• -0
• biginteger(0n)
• empty string(""),”,“
• document.all

#javascript truthy values examples

truthy values are values that evaluate to true during the execution of the boolean expression.

• true
• []
• numbers
• “0”, “false”, any strings
• Infinity
• -Infinity
• new Date()

#Javascript truthy and falsy operation check example

truthy and falsy values use in conditional expression and equal operators.

Here is an example to check if condition

function isTrutyFalsy(arg) {
  if (arg) {
    console.log(arg + ":  Truthy");
  } else {
    console.log(arg + ":  falsy");
  }
}

And the truthy examples.

isTrutyFalsy(134);
isTrutyFalsy(true);
isTrutyFalsy({});
isTrutyFalsy([]);
isTrutyFalsy(42);
isTrutyFalsy("0");
isTrutyFalsy("false");
isTrutyFalsy(new Date());
isTrutyFalsy(-15);
isTrutyFalsy(42n);
isTrutyFalsy(1.1);
isTrutyFalsy(-2.5);
isTrutyFalsy(Infinity);
isTrutyFalsy(-Infinity);

Output:

134:  Truthy
true:  Truthy
[object Object]:  Truthy
:  Truthy
42:  Truthy
0:  Truthy
false:  Truthy
Mon Jan 03 2022 05:45:05 GMT+0000 (Coordinated Universal Time):  Truthy
-15:  Truthy
42:  Truthy
1.1:  Truthy
-2.5:  Truthy
Infinity:  Truthy
-Infinity:  Truthy

falsy examples:

isTrutyFalsy("");
isTrutyFalsy("");
isTrutyFalsy(``);
isTrutyFalsy(0);
isTrutyFalsy(-0);
isTrutyFalsy(-0n);
isTrutyFalsy(false);
isTrutyFalsy(NaN);
isTrutyFalsy(null);
isTrutyFalsy(undefined);

Output:

:  falsy
:  falsy
:  falsy
0:  falsy
0:  falsy
0:  falsy
false:  falsy
NaN:  falsy
null:  falsy
undefined:  falsy

#Javascript truthy and falsy checklist

Following is a table for truthy and falsy values in javascript boolean expressions.