undefined null " each judge once): if( (this.$route.query.openid != undefined || this.$route.query.openid != null || this.$route.query.openid != "" ) && window.localStorage.getItem("openid") != "")
{
......
} I would like to ask JS or Vue or ES is there any way to directly determine whether a variable is valid at once?
the answer of @ original sin adopted by the landlord is not accurate enough. With a rigorous and responsible attitude, it is necessary to add that when making a judgment first, if a variable is not declared, it cannot be judged directly. For example, the following judgment will report an error.
const nullReg = /^(undefined|null|)$/;
if(!nullReg.test(this.$route.query.openid) && !nullReg.test(window.localStorage.getItem('openid'))) {
...
}
just can t show it. Thank you very much for your advice. ...
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