实现的小功能：判断报名是否重复，是返回true,否返回false.

本文链接：https://blog.youkuaiyun.com/u012986638/article/details/18321889

本文对比分析了三种JavaScript实现方法的优缺点，旨在帮助开发者选择最适合的实现方式。

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有下面三种实现方法，你喜欢哪种呢？

(1)

Message.judge_sign_up_repeat = function (sms_json) {
    var sign_ups = JSON.parse(localStorage.sign_ups);
    var activity = _.filter(sign_ups, function (num) {           
        return num.activity_id == Activity.get_current_activity()
    }) 
    return  _.some(activity, function (list) { 
        return list.phone == Message.save_phone(sms_json)
    }) 
}

(2)

Message.judge_sign_up_repeat = function (sms_json) {
    var sign_ups = JSON.parse(localStorage.sign_ups);
    var activity = _.find(sign_ups, function (num) {           
        return num.activity_id == Activity.get_current_activity()
    }) 
    var sign_up_reepeat= _.some(activity, function (value,key) { 
        return key=='phone' ? value == Message.save_phone(sms_json) : '' 
    })
    return sign_up_repeat 
}

(3)

Message.judge_sign_up_repeat = function (sms_json) {
    var sign_ups = JSON.parse(localStorage.sign_ups);
    var activity = _.find(sign_ups, function (num) {           
        return num.activity_id == Activity.get_current_activity()
    }) 
    var sign_up_repeat = activity ? activity['phone']== Message.save_phone(sms_json) : false
    }
    return sign_up_repeat 
}