函数 预编译

var str = false + 1;
        console.log(str);//   1
        var demo = false == 1;
        console.log(demo);//  0
        if (typeof(a) && -true + (+undefined) + ''){
            console.log('不错'); 
        }
        if (11 + "11" * 2 ==33){
            console.log('不错')
        }    
        !!" " + !!"" -!!false || console.log('pork!!');

 (window.foo || (window.foo = 'bar'))
        console.log(foo)

两个题可以做做看

来源：https://www.cnblogs.com/punisher999/p/12150777.html