JavaScript好題まとめ共有(更新を続け、好題を見たら書く)

a = 100;
function demo(e) {
	function e() {  }
	arguments[0] = 2;
	console.log(e);
	if(a){
		var b = 123;
		function c() {
		}
	}
	var c;
	a = 10;
	var a;
	console.log(b);
	f = 123;
	console.log(c);
	console.log(a);
}
var a;
demo(1);
console.log(a);
console.log(f);

function bar(){
	return foo;
	foo = 100;
	function foo() {}
	var foo = 111;
}
console.log(bar()); 

console.log(bar());
function bar() {
	foo = 10;
	function foo() {}
	var foo = 11;
	return foo;
}

if (typeof (a) && -true + (-undefined) + "") {
		document.write("    ");
}
if(11 + "11" * 2 == 33){
	document.write("    ");
}
!!" " + !!"" - !!false || document.write('      ，    ');

(window.x || (window.x = "bar")); 
console.log(window.x);

function a() {
	console.log('a');
}();          //  
function a(a, b, c, d) {
		console.log(a + b + c + d);
}(1, 2, 3, 4);//   ，