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题目：

完善编辑器中的every函数，如果集合collection)中的所有对象都存在对应的属性pre)，并且属性pre)对应的值为真。函数返回ture。反之，返回false。

记住：你只能通过中括号来访问对象的变量属性pre)。

提示：你可以有多种实现方式，最简洁的方式莫过于Array.prototype.every)。

例子：

every[{“user”: “Tinky-Winky”, “sex”: “male”}, {“user”: “Dipsy”, “sex”: “male”}, {“user”: “Laa-Laa”, “sex”: “female”}, {“user”: “Po”, “sex”: “female”}], “sex”) 应该返回 true。
every[{“user”: “Tinky-Winky”, “sex”: “male”}, {“user”: “Dipsy”}, {“user”: “Laa-Laa”, “sex”: “female”}, {“user”: “Po”, “sex”: “female”}], “sex”) 应该返回 false。
every[{“user”: “Tinky-Winky”, “sex”: “male”, “age”: 0}, {“user”: “Dipsy”, “sex”: “male”, “age”: 3}, {“user”: “Laa-Laa”, “sex”: “female”, “age”: 5}, {“user”: “Po”, “sex”: “female”, “age”: 4}], “age”) 应该返回 false。
every[{“name”: “Pete”, “onBoat”: true}, {“name”: “Repeat”, “onBoat”: true}, {“name”: “FastFoward”, “onBoat”: null}], “onBoat”) 应该返回 false
every[{“name”: “Pete”, “onBoat”: true}, {“name”: “Repeat”, “onBoat”: true, “alias”: “Repete”}, {“name”: “FastFoward”, “onBoat”: true}], “onBoat”) 应该返回 true
every[{“single”: “yes”}], “single”) 应该返回 true
every[{“single”: “”}, {“single”: “double”}], “single”) 应该返回 false
every[{“single”: “double”}, {“single”: undefined}], “single”) 应该返回 false
every[{“single”: “double”}, {“single”: NaN}], “single”) 应该返回 false

代码：

<script type="text/javascript">
	function everycollection, pre) {
		// Is everyone being true?
		var flag = true;
		for var i in collection) {
			// console.logcollection[i]);
			if !collection[i][pre]) {
				flag = false;
			}
		}
		return flag;
	}
</script>