判断对象数组中每个人是否成年，大于17成年，否则未成年

var arr = [
            {name:'jerry',sex:'man',age:14},
            {name:'jack',sex:'woman',age:19},
            {name:'bill',sex:'man',age:18}
        ]
        var every = arr.every(function(obj){  //every  一假即假
            return obj.age > 17   
        })
        var some = arr.some(function(obj){   // some  一真即真
            return obj.age >17
        })
        console.log(every,some)  //false  true

应用场景： 注册或登陆页判断所填内容是否为空