const boolean = new Boolean(false);
console.log(typeof boolean);
console.log(boolean.valueOf());
注意boolean是一个对象
console.log(Boolean([]));//空数组的布尔值为真
var array = [];
console.log(Number(array));
console.log(array==false);
if([]){//空对象也是如此。
console.log('a');
}
但空数组类型转换后等于0.但if语句里为真。
转换
let number = 0 ;
console.log(typeof number);
number = !number;
console.log(number);
//2:console.log(Boolean(number));