判断

const chinese = /[^\u4E00-\u9FA5]/g

const number = /[^\d]/g;

const englishAndNum =/[\W]/g

if ((chinese.test(this.data.username))) {
    wx.showToast({ title: "只允许输入中文", icon: "none" });
    return false;
}

if ((number.test(this.data.username))) {
    wx.showToast({ title: "只允许输入数字", icon: "none" });
    return false;
}

if ((englishAndNum.test(this.data.username))) {
    wx.showToast({ title: "只允许输入英文加数字", icon: "none" });
    return false;
}