https://stackoverflow.com/questions/5746947/c-sharp-string-isnullorempty-javascript-equivalent
if(!theString) { alert("the string is null or empty"); }
https://stackoverflow.com/questions/5746947/c-sharp-string-isnullorempty-javascript-equivalent
if(!theString) { alert("the string is null or empty"); }
C# String.IsNullOrEmpty Javascript equivalent
原文：https://www.cnblogs.com/chucklu/p/8575158.html