JavaScript中的true和false

https://ask.csdn.net/questions/1024438

https://www.cnblogs.com/lhyhappy365/p/6076512.html

https://www.cnblogs.com/sunmarvell/p/9048222.html

https://www.cnblogs.com/canger/p/6374185.html

https://segmentfault.com/q/1010000015470614/a-1020000015470827undefined、NaN、0、null和空字符串''均被视为false 除上述以外的其它情况一律被视作true

JavaScript中的true和false