1// JS Essentials: Falsy Values
2
3false
4undefined
5null
6NaN
70 or +0 or -0
8"" or '' or `` (empty string)
9
10// Everything else is truthy

1// Falsy values:
20
3''
4undefined
5null
6NaN

1false		//The keyword false.
20			//The Number zero (so, also 0.0, etc., and 0x0).
3-0			//The Number negative zero (so, also -0.0, etc., and -0x0).
40n, -0n		//The BigInt zero and negative zero (so, also 0x0n/-0x0n).
5"", '', ``	//Empty string value.
6null		//the absence of any value.
7undefined	//the primitive value.
8NaN			//not a number.
9
10document.all	
11//Objects are falsy if and only if they have the [[IsHTMLDDA]] internal slot.
12//That slot only exists in document.all and cannot be set using JavaScript.

1    let a = false
2    let b = 0
3    let c = -0
4    let d = 0n
5    let e = ''
6    let f = null
7    let g = undefined
8    let h = NaN

1if (true)
2if ({})
3if ([])
4if (42)
5if ("0")
6if ("false")
7if (new Date())
8if (-42)
9if (12n)
10if (3.14)
11if (-3.14)
12if (Infinity)
13if (-Infinity)
14

1/*
2	Yes.
3    Full list of falsy values:
4    Anything evaluated to be 0
5    '', "", or ``
6    null
7    undefined
8    NaN
9    Obviously false
10    Big integers relative to 0n
11    -------------------------------------------------------------------------
12    To clarify, line 31 will print false.
13*/
14var someCheckIsTrue = false;
15const checks = [
16  0,
17  '',
18  "",
19  ``,
20  null,
21  undefined,
22  NaN,
23  false,
24  0n
25];
26for (const check of checks) {
27  if (check) {
28    someCheckIsTrue = true;
29  }
30}
31console.log(someCheckIsTrue);