Conditional Operator

condition ? expr1 : expr2 

'The fee is ' + (isMember ? '$2.00' : '$10.00');

var elvisLives = Math.PI > 4 ? 'Yep' : 'Nope';

var firstCheck = false,
    secondCheck = false,
    access = firstCheck ? 'Access denied' : secondCheck ? 'Access denied' : 'Access granted';
  
console.log(access); // logs "Access granted"

var condition1 = true,
    condition2 = false,
    access = condition1 ? (condition2 ? "true true": "true false") : (condition2 ? "false true" : "false false");

console.log(access); // logs "true false"

var stop = false, age = 16;

age > 18 ? location.assign('continue.html') : stop = true;

var stop = false, age = 23;

age > 18 ? (
    alert('OK, you can go.'),
    location.assign('continue.html')
) : (
    stop = true,
    alert('Sorry, you are much too young!')
);

var age = 16;

var url = age > 18 ? (
    alert('OK, you can go.'), 
    // alert returns "undefined", but it will be ignored because
    // isn't the last comma-separated value of the parenthesis
    'continue.html' // the value to be assigned if age > 18
) : (
    alert('You are much too young!'),
    alert('Sorry :-('),
    // etc. etc.
    'stop.html' // the value to be assigned if !(age > 18)
);

location.assign(url); // "stop.html"

var func1 = function( .. ) {
  if (condition1) { return value1 }
  else { return value2 }
}

var func2 = function( .. ) {
  return condition1 ? value1 : value2
}

var func1 = function( .. ) {
  if (condition1) { return value1 }
  else if (condition2) { return value2 }
  else if (condition3) { return value3 }
  else { return value4 }
}

var func2 = function( .. ) {
  return condition1 ? value1
       : condition2 ? value2
       : condition3 ? value3
       :              value4
}