js 字符串全部替换

str = "omr040qTwjR5ZAvmhxm<x>l2aKClOPQ";

// 把 <x> 替换为 x
str.replace(/<x>/g, "x");

结果

omr040qTwjR5ZAvmhxmxl2aKClOPQ

var memberIds = [
    '5bd2e9846527950049805f9c',
];
memberIds.forEach(function(memberId) {
    db.member.find({
        '_id': ObjectId(memberId),
    }).snapshot().forEach(function(member){
        var newSocials = []
        member.socials.forEach(function(social) {
            social.unionId = social.unionId.replace(/<x>/g, "x");
            newSocials.push(social)
        })
        member.socials = newSocials
        db.member.save(member)
        print('memberId: ' + member._id + ' done')
    })
});