測試1: (未宣告變數自動提升為全域性變數)

test1();
function test1() {
    function setName() {
        name = '張三'; // 此處沒有var宣告，提升至全域性
    }
    setName();
    console.log(name);// '張三'
}

test2();
function test2() {
    var a = 1;
    function haha() {
        console.log(a);
        var a=1;
    }
    haha(); // undefined
}
 

test3();
function test3() {
    var b=2;
    function hehe(){
        window.b = 3; // 此時的b為全域性變數的b
        console.log(b); // 此時的b是函式test3()裡的b為2
    }
    hehe();
}

test4();
function test4() {
    c = 5;
    function heihei() {
        var c;
        window.c = 3;
        console.log(c); // 函式heihei內的c為undefined
        console.log(window.c); // 3
    }
    heihei();
}
 

test5();
function test5() {
    var arr = [];
    arr[0] = '1';
    arr[1] = 'b';
    arr[9] = 100;
    console.log(arr.length); // 10
}

test6();
function test6() {
    var a = 1;
    console.log(a++); // 1
    console.log(++a); // 3
    console.log(null == undefined); // true
    console.log(null === undefined);// false
    console.log(1 == "1"); // true
    console.log(1 === "1"); // false
    console.log(NaN === NaN) // false;
}
 

test7();
function test7() {
    console.log(typeof 1); // number
    console.log(typeof "hello"); // string
    console.log(typeof typeof "hello"); // string
    console.log(typeof !!"hello"); // boolean
    console.log(typeof /[0-9]/); // object
    console.log(typeof {}); // object
    console.log(typeof null); // object
    console.log(typeof undefined); // undefined
    console.log(typeof [1, 2, 3]); // object
    console.log(toString.call([1, 2, 3])); // [object Array]
    console.log(typeof function () {}); // function
}

test8();
function test8() {
    console.log(parseInt(3.14));// 3
    console.log(parseFloat('3.01aaa'));// 3.01
    console.log(parseInt('aa1.2'));// NaN;
    console.log(parseInt('8.00',16));// 8
    console.log(parseInt('0x8',16));// 8
    console.log(parseInt('8.00',10));// 8
    console.log(parseInt('010',8));// 10
    console.log(parseInt('1000',2));// 1000
}

test9();
function test9() {
    function bar() {
        return foo;
        foo = 10;
        function foo(){};
    }
    console.log(typeof bar()); // 'function'
}

test10();
function test10() {
    var foo = 1;
    function bar() {
        foo = 10;
        console.log(typeof foo);
        return;
        function foo(){};
    }
    bar(); // number
    console.log(foo); // 1
}

test11();
function test11() {
    console.log(typeof a); // function
    var a = 3;
    function a(){};
    console.log(typeof a); // number
}

test12();
function test12() {
    function foo(a) {
        console.log(a);// 1
        arguments[0] = 2;
        console.log(a);// 2
        console.log(arguments.length);// 3
    }
    foo(1,3,4);
}

test13();
function test13() {
    var foo = function bar(name) {
        console.log("hello " + name);
    }
    foo("world");
    console.log(bar); // 此處會報錯 bar is not defined
}

test14();
function test14() {
    function foo() {
        console.log('I am foo');
    }
    console.log('正常執行');
    setTimeout((function(){
        console.log('定時器大灰狼來啦');
    }),0);
    foo();
}