找到子对象的最大值 [英] find max value of a child object

问题描述

在javascript中查找子对象的最大值的优雅方法是什么？

What would be an elegant way to find the max value of a child object in javascript?

示例：

找到此对象的最大数量值（此处显示为json）：

find the max quantity value of this object (here shown as json):

{"density":[
  {"price":1.22837, "quantity":48201},
  {"price":1.39837, "quantity":28201},
  {"price":1.40107, "quantity":127011},
  {"price":1.5174,  "quantity":75221},
  {"price":1.60600, "quantity":53271}
]}

感谢您的任何建议！

PS：只是为了澄清：当然我可以循环，但我认为会有一个更优雅的方式...

PS: just to clarify: of course i could loop through, but i thought there would be a more elegant way ...

推荐答案

这是 reduce Array原型的方法：

There's the reduce method of the Array prototype:

var arr = JSON.parse(objstring)["density"];
var max = arr.reduce(function(a, b) {
   return Math.max(a, b.quantity);
}, 0);

另一个解决方案是

var max = Math.max.apply(null, arr.map(function(item){
   return item["quantity"];
}));

对于更优雅的方式，有功能库提供getter工厂函数和更多Array方法。具有此类库的解决方案可能看起来像

For more "elegant" ways there are functional libraries which provide getter factory functions and more Array methods. A solution with such a library could look like

var max = arr.get("quantity").max();

这与上面的完全相同，但表达更好。

which would do exactly the same as the above one, but nicer expressed.

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