我正在寻找一个非常快速,干净和有效的方法来获得以下JSON切片中的最大“y”值:

[
  {
    "x": "8/11/2009",
    "y": 0.026572007
  },
  {
    "x": "8/12/2009",
    "y": 0.025057454
  },
  {
    "x": "8/13/2009",
    "y": 0.024530916
  },
  {
    "x": "8/14/2009",
    "y": 0.031004457
  }
]

for循环是唯一的方法吗?我很喜欢用Math.max。


当前回答

又快又脏:

Object.defineProperty (Array.prototype“分钟”, { 价值:函数(f) { F = F || (v => v); 返回。Reduce ((a, b) => (f(a) < f(b)) ?A: b); } }); Object.defineProperty (Array.prototype‘麦克斯’, { 价值:函数(f) { F = F || (v => v); 返回。Reduce ((a, b) => (f(a) > f(b)) ?A: b); } }); console.log ([1, 2, 3] .max ()); console.log([1, 2, 3]。Max (x => x*(4-x))); console.log ([1, 2, 3] .min ()); console.log([1, 2, 3]。Min (x => x*(4-x)));

其他回答

在对象数组中找到属性“Y”值最大的对象

一种方法是使用Array reduce..

const max = data.reduce(function(prev, current) {
    return (prev.y > current.y) ? prev : current
}) //returns object

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce http://caniuse.com/#search=reduce (IE9及以上版本)

如果你不需要支持IE(只支持Edge),或者可以使用预编译器,比如Babel,你可以使用更简洁的语法。

const max = data.reduce((prev, current) => (prev.y > current.y) ? prev : current)

求数组中所有对象的y的最大值:

    Math.max.apply(Math, array.map(function(o) { return o.y; }))

或者在更现代的JavaScript中:

    Math.max(...array.map(o => o.y))
// Here is very simple way to go:

// Your DataSet.

let numberArray = [
  {
    "x": "8/11/2009",
    "y": 0.026572007
  },
  {
    "x": "8/12/2009",
    "y": 0.025057454
  },
  {
    "x": "8/13/2009",
    "y": 0.024530916
  },
  {
    "x": "8/14/2009",
    "y": 0.031004457
  }
]

// 1. First create Array, containing all the value of Y
let result = numberArray.map((y) => y)
console.log(result) // >> [0.026572007,0.025057454,0.024530916,0.031004457]

// 2.
let maxValue = Math.max.apply(null, result)
console.log(maxValue) // >> 0.031004457

如果你(或这里的某人)可以自由使用lodash实用程序库,它有一个maxBy函数,在你的情况下会非常方便。

因此你可以用as such:

_.maxBy(jsonSlice, 'y');

它返回对象简化的@andy polhill answare

var data = ( { y: 90 }, { y: 9 }, { y: 8 } ] Const Max = data。Reduce ((prev, current)=> ((prev, current))Y >电流。Y) ?当前),0)//返回对象 console.log (max)