quirks.md

Quirks

What will be the output?

function foo(x) {
console.log(arguments)
return x
}
foo(1, 2, 3, 4, 5)

and

function foo(x) {
console.log(arguments)
return x
}(1, 2, 3, 4, 5)

---

What will be the output

a = [1,2,3,4]
a[1.5] = 1.5
a // ?

---

What will be the output

function foo(){console.log("hello")}
foo.call.call.call.apply(function bar(x) {console.log(x)}, [this,"world"])

What will be the output

console.log("1" + 2);
console.log(2 + "1");
console.log(1 + 2 + 3 + 4 + "5"); //<-- nb

---

Make it true

var a;
/* put your code here */
a !== a; // should be true

What will be the output

var scores = [98, 74,85, 77, 93,100,89];
var total = 0;
for (var score in scores) { 
  total += score;
} 
var mean = total / scores.length;
console.log(mean); //?

---

What will be the output

[2, 3, -1, -6, 0, -108, 42, 10].sort();

What is the difference between 0 / -0 ?

---

What will be the output

var y = 1;
if (function f(){}) {
  y += typeof f;
}
console.log(y);

---

What will be the output

var foo = function bar(){ return 12; };
typeof bar();  

---

What will be the output

var a={},
    b={key:'b'},
    c={key:'c'};

a[b]=123;
a[c]=456;
console.log(a[b]);

---

What will be the output?

['11','11','11','11'].map(parseInt)

---

what will display alert?

function aaa() {
    return
    {
        test: 1
    };
}
alert(typeof aaa());

What is alerted?

function bar() {
    return foo;
    foo = 10;
    function foo() {}
    var foo = '11';
}
alert(typeof bar());

---

Output?

console.log("1" - - "1")

---

what is the output?

var x = 3;
var foo = {
    x: 2,
    baz: {
        x: 1,
        bar: function() {
            return this.x;
        }
    }
}
var go = foo.baz.bar;
alert(go());
alert(foo.baz.bar());

---

output?

var myArr = ['foo', 'bar', 'baz'];
myArr.length = 0;
myArr.push('bin');
console.log(myArr);

---

Output?

var x = 0;
function foo() {
    x++;
    this.x = x;
    return foo;
}
var bar = new new foo;
console.log(bar.x);

---

result?

var bar = 1,
    foo = {};
foo: {
    bar: 2;
    baz: ++bar;
};
foo.baz + foo.bar + bar;

---

output?

var myArr = ['foo', 'bar', 'baz'];
myArr[2];
console.log('2' in myArr);

output?

function foo(a, b) {
    arguments[1] = 2;
    alert(b);
}
foo(1);

---

What value is alerted?

function foo(){}
delete foo.length;
alert(typeof foo.length);

---

output ?

var f = function g(){ return 23; };
typeof g();

---

output?

var f = (function f(){ return "1"; }, function g(){ return 2; })();
typeof f;

---

output ?

var a = 1,
    b = function a(x) {
        x && a(--x);
    };
alert(a);

---

output?

function a() {
    alert(this);
}
a.call(null);

---

result?

var foo = bar ? bar : 0;

---

How to empty an array in JavaScript ?

var arrayList =  ['a','b','c','d','e','f'];
// how many ways? compare them

---

result? =)

var a = (1,5 - 1) * 2

---

output?

// http://stackoverflow.com/questions/39277394/why-settimeout-calls-make-different-result
setTimeout(function() {
  setTimeout(function() {
    console.log('foo');
  }, 50);
}, 100);
setTimeout(function() {
  setTimeout(function() {
    console.log('baz');
  }, 100);
}, 50);

---

result?

5 > 3 > 2

---

what is logged in the console?

var a;
if (a = (1+1==2)) {
    console.log(a);
} else {
    console.log('false');
}

---

are next expressions equal ? what's the result for both?

1 << 33
(1 << 31) << 2

---

What will be the output

let y = 1;
if (function F(){}) {
  y += typeof F;
}
console.log(y);