获取对象键的最高数值N值
问题描述：
var foo = {a:1, b:2, c:3, d:4, e:5, f:6, g:7}
通缉结果:(获得前3个键价值）
Wanted result: (get top 3 keys by value)
{e:5, f:6, g:7}
说明：
对于给定的密钥/ value基本对象，你如何获得3个顶部值，但不仅仅是值而是键？钥匙可以是任何东西。假设值是整数。
Explanation:
For a given key/value basic object, how would you get the 3 top values, but not just the values but also the keys? keys could be anything. lets say values are integers.
应该记住性能。
答
您可以将属性提取到数组中，然后对数组进行排序：
You can extract the properties into an array, then sort the array:
var foo = {a:1, b:2, c:3, d:4, e:5, f:6, g:7}
var props = Object.keys(foo).map(function(key) {
return { key: key, value: this[key] };
}, foo);
props.sort(function(p1, p2) { return p2.value - p1.value; });
var topThree = props.slice(0, 3);
如果您希望将结果作为对象，只需将其缩减为一个
If you want the result as an object, just reduce it back to one
var topThreeObj = props.slice(0, 3).reduce(function(obj, prop) {
obj[prop.key] = prop.value;
return obj;
}, {});