[fun] various forms of ternary operator in JavaScript

[fun] various forms of ternary operator in JavaScript.js

// add your variants of
a ? b : c
// in comments :)
// a is boolean
// b and c - any type
// lazy evaluation isnt important

({
  'true': b, 
  'false': c
})[a]

[c, b][a]

[0 ,1 ,2 ,3 , b, c][String(a).length]

a && Object(b) || Object(c)

switch(a) {
  case true: return b
  case false: return c
}

if(a) {
  return b
}
else {
  return c
}

(String(a)
  .replace('true', function() {
    ret = b
  })
  .replace('false', function() {
    ret = c
  })
)

(
  (
    [
      0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 
      function() {
        ret = c
      }
    ][parseInt(String(a)[1], 16)] 
  )
  || function() {
    ret = b
  }
)() 

[c, b][parseInt(!a, 011 << 2) >> 0xDEADBEAF >> 011]

({116: b, 102: c})[String(a).charCodeAt(0)]

a << 2 && b || c

@bga a && Object(b) || Object(c) won't work if b or c are scalar (amongst other cases).

as a && b || c wouldn't work either if b is falsey:

(a && [b] || [c])[0]

[b, c][2+~a]

Boolean.prototype.ternary = function (b, c) { /* WARNING INCEPTION DETECTED */ return this ? b : c }
→ a.ternary(b, c)

(a * 2 == a && c || d)[0]

@naholyr Object wrapper to make 0, empty string and false non falsey

true && 0 || 1 // 1
true && Object(0) || 1 // 0

Of course it has issue - Object(null) <=> {}

@naholyr but your fix (wrap into array) is better

var IFTHENELSE=function (x) { return function(y) { return function(z) {return x(y(z))}}}
var a=function(x) {return function(y) {return x}}
var result=IFTHENELSE(a)(function(_) {return "b"})(function(_){return "c"})()
console.log(result)
// b

The previous version was wrong. it works with true(=a) but no with false. The new one works and... look! it requires another ternary operator

var IFTHENELSE=function (x) { return function(y) { return function(z) {return (x(y))(z)}}}
var TRUE=function(x) {return function(y) {return x}}
var FALSE=function(x) {return function(y) {return y}}
function ternary (a,b,c) {return IFTHENELSE(a?TRUE:FALSE)(function(_) {return b})(function(_){return c})()}
console.log(ternary("a","b","c"))
// b
console.log(ternary(false,"b","c"))
//c

To easily test these in your console, run this line:

var a = true, b = 'a is true', c = 'a is false';

Then copy-paste any snippet from this page to check if it works correctly. Try setting a = false too!

---

({t:b,f:c})[(''+a).charAt()]

…or, in slightly more readable form:

({ 't': b, 'f': c })[String(a).charAt()]

---

({'':b,e:c})[(''+a).slice(4)]

…or, in slightly more readable form:

({ '': b, 'e': c})[String(a).slice(4)]

---

({ true: b, false: c })[String.fromCharCode(a) != '\0']

---

({ true: b, false: c })[a['\x76\x61\x6c\x75\x65\x4f\x66']('\x70\x72\x6f\x62\x6c\x65\x6d\x3f')]

---

({ true: b, false: c })[Boolean((+a).toExponential().indexOf('0'))]

…or, with some extra mindfuck:

[c, b][(+(+a)['\x74o\x45x\x70o\x6ee\x6e\x74i\x61l']('H̹̙̦̮͉̩̗̗ͧ̇̏̊̾Eͨ͆͒̆ͮ̃͏̷̮̣̫̤̣ ̵̞̹̻̀̉̓ͬ͑͡ͅCͯ̂͐͏̨̛͔̦̟͈̻O̜͎͍͙͚̬̝̣̽ͮ͐͗̀ͤ̍̀͢M̴̡̲̭͍͇̼̟̯̦̉̒͠Ḛ̛̙̞̪̗ͥͤͩ̾͑̔͐ͅṮ̴̷̷̗̼͍̿̿̓̽͐H̙̙̔̄͜')[0])]

[c, b][a] doesn't work for me: it returns undefined, which seems expected. But [c, b][ ~ ~ a] works for true/false/1/0 and [c, b][!! ~ ~ a] works for negative numbers (at least if you expect them to resolve to true).

Shouldn't this:

[c, b][a]

Be this: (?)

[c, b][+!!a]

Or:

[b,c][+!a]

IMHO, this is the most readable ternary operation:

Array(2).concat(b, c)[String(a).match(/(t)|(f)/).join().split(',,').push(1)]

@padolsey It could simply be [c, b][+a], as the gist states that a is a boolean (not just a truthy/falsy value). But yeah, [c, b][a] doesn’t look right.

I believe

[c, b][a]

should be

[c, b][+a]

Edit: Damn you mathias! :)

@jneira I love that lambda calculus inspired version. How about this? (Credits to you, this is just sugar)

var lambdas = {
  true: function(x) {return function(y) {return x}},
  false: function(x) {return function(y) {return y}},
  ifthenelse: function (x) { return function(y) { return function(z) {return (x(y))(z)}}}
}
function ternary (a,b,c) {
  return lambdas.ifthenelse(lambdas[!!a])(function(_) {return b})(function(_){return c})()
}
console.log(ternary("a","b","c"))
// b
console.log(ternary(false,"b","c"))
//c

better, but credits to Alonzo Church!, we are simple mortals