var 1 = 1; var 1ab = 1; var a = 1 = 2;
变量 or 函数未被声明
test(); console.log(a);
var a = 1; console.log(a) = 1;
数组长度设置负值
var arr = [1, 2, 3]; arr.length = -1;
对象方法参数,超出可行范围
var num = new Number(66.66); console.log(num.toFixed(-1));