javascript falsy values code example

Example 1: javascript falsy values

the number 0
the BigInt 0n
the keyword null
the keyword undefined
the boolean false
the number NaN
the empty string "" (equivalent to '' or ``)

Example 2: javascript falsy

// Falsy values:
0
''
undefined
null
NaN

Example 3: falsy values javascript

false		//The keyword false.
0			//The Number zero (so, also 0.0, etc., and 0x0).
-0			//The Number negative zero (so, also -0.0, etc., and -0x0).
0n, -0n		//The BigInt zero and negative zero (so, also 0x0n/-0x0n).
"", '', ``	//Empty string value.
null		//the absence of any value.
undefined	//the primitive value.
NaN			//not a number.

document.all	
//Objects are falsy if and only if they have the [[IsHTMLDDA]] internal slot.
//That slot only exists in document.all and cannot be set using JavaScript.

Example 4: js falsy values

let a = false
    let b = 0
    let c = -0
    let d = 0n
    let e = ''
    let f = null
    let g = undefined
    let h = NaN

Example 5: is null falsy javascript

/*
	Yes.
    Full list of falsy values:
    Anything evaluated to be 0
    '', "", or ``
    null
    undefined
    NaN
    Obviously false
    Big integers relative to 0n
    -------------------------------------------------------------------------
    To clarify, line 31 will print false.
*/
var someCheckIsTrue = false;
const checks = [
  0,
  '',
  "",
  ``,
  null,
  undefined,
  NaN,
  false,
  0n
];
for (const check of checks) {
  if (check) {
    someCheckIsTrue = true;
  }
}
console.log(someCheckIsTrue);

Example 6: javascript falsy values

if (true)
if ({})
if ([])
if (42)
if ("0")
if ("false")
if (new Date())
if (-42)
if (12n)
if (3.14)
if (-3.14)
if (Infinity)
if (-Infinity)