js ??数据类型转换

var n1 = 123;var n2 = ‘123‘;var n3 = n1+n2;// 隐式转换console.log(typeof n3);

var str1 = String(n1);console.log(typeof str1);var num = 234;console.log(num.toString())

var ?stringNum = ‘789.123wadjhkd‘;var num2 = ?Number(stringNum);console.log(num2)// parseInt()可以解析一个字符串 并且返回一个整数console.log(parseInt(stringNum))console.log(parseFloat(stringNum));

var b1 = ‘123‘; ?真var b2 = 0; ?????假var b3 = -123 ???真var b4 = Infinity; ?真 ??特殊的number ?var b5 = NaN; ??????假 ??特殊的number 

var b6=undefined 假
 var b7 = null; ??假

// 非0既真 console.log(Boolean(b7))