_6413

    function isValidEmail(e) {
        const b = /^(([^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
        return b.test((e + "").toLowerCase())
    }

2. You're calling toLowerCase() yet the regex is already case-agnostic.

If you're going to attempt email address validation, either go all out[1], or just use isValidEmail=(e)=>~e.indexOf("@")