建议使用 === !==
"" == 0 true
false == 0 true
"" === 0 false
"undefined" == undefined false
'' == null false
null == undefined true
null === undefined false
建议使用 === !==
"" == 0 true
false == 0 true
"" === 0 false
"undefined" == undefined false
'' == null false
null == undefined true
null === undefined false