<script>
// !(!"Number(undefined)");
/*
* "" '' `` 都是字符串 => "Number(undefined)"就是一个字符串
* !"Number(undefined)" 转换为布尔在取反 => false
* !false => true
*/
// isNaN(parseInt(new Date())) + Number([1]) + typeof undefined;
/*
* + 是最后计算的，先把每一项的值都算出来，最后相加
* isNaN(parseInt(new Date())) 从最里层开始逐一向外层计算
* new Date() => 当前本机日期（对象）
* parseInt(对象) => parseInt("Fri Mar 06 2020 11:43:18 GMT+0800") =>NaN
* isNaN(NaN) => true
* Number([1])
* Number("1") =>1
* typeof undefined
* =>"undefined"
* true + 1 + "undefined"
* true + 1 => 2
* 2 + "undefined" => "2undefined"
*/
// Boolean(Number("")) + !isNaN(Number(null)) + Boolean("parseInt([])") + typeof !(null);
/*
* Boolean(Number(""))
* Number("") => 0
* Boolean(0) => false
* !isNaN(Number(null))
* Number(null) => 0
* isNaN(0) => false
* !false => true
* Boolean("parseInt([])")
* "parseInt([])" 他是一个字符串，并不是转换数字啥的
* => true
* typeof !(null)
* !(null) => true
* typeof true => "boolean"
* false + true + true + "boolean" => "2boolean"
*/
// parseFloat("1.6px") + parseInt("1.2px") + typeof parseInt(null);
/*
* parseFloat("1.6px") => 1.6
* parseInt("1.2px") => 1
* typeof parseInt(null)
* parseInt(null) => parseInt('null') => NaN
* typeof NaN => "number"
* 1.6 + 1 + "number" => '2.6number'
*/
// isNaN(Number(!!Number(parseInt("0.8"))));
/*
* parseInt("0.8") => 0
* !!Number(0) => false
* Number(false) => 0
* isNaN(0) => false
*/
// console.log(1 + "2" + "2");
/*
* '122'
*/
// !typeof parseFloat("0");
/*
* parseFloat("0") => 0
* typeof 0 => "number"
* !"number" => false
*/
// Number("");
/* 0 */
// typeof "parseInt(null)" + 12 + !!Number(NaN);
/*
* typeof "parseInt(null)" => "string"
* 12
* !!Number(NaN) => false
* => "string12false"
*/
// !typeof (isNaN("")) + parseInt(NaN);
/*
* !typeof (isNaN(""))
* isNaN("") => isNaN(Number("")) => isNaN(0) => false
* typeof false => "boolean"
* !"boolean" => false
* parseInt(NaN)
* parseInt(String(NaN)) => parseInt('NaN') => NaN
* false + NaN => NaN
*/
// typeof !parseInt(null) + !isNaN(null);
/*
* typeof !parseInt(null)
* parseInt(null) => parseInt('null') => NaN
* !NaN => true
* typeof true => "boolean"
* !isNaN(null)
* isNaN(null) => isNaN(Number(null)) => isNaN(0) => false
* !false => true
* "boolean" + true => "booleantrue"
*/
</script>
