javascript - 根据最接近的数字返回值

Question

在代码片段中，您将找到一个函数，该函数根据您在 var found = getDistanceNumber('Saturn'); 中键入的行星返回和输出属于数组内行星的距离

我想使用这段代码，而不是像现在编程那样返回行星的距离，而是离它最近的行星的名称。所以如果我有 Saturn 作为参数，我希望它检查它的距离是多少，找到数组中最近的距离，并输出属于那个的行星。在这种情况下，它就是木星。

我该怎么做？

var data = [
 {
   "Planet": "Mercury",
   "Distance": "-92 million"
 },
 {
   "Planet": "Venus",
   "Distance": "-42 million"
 },
 {
   "Planet": "Earth",
   "Distance": "0"
 },
 {
   "Planet": "Mars",
   "Distance": "78 million"
 },
 {
   "Planet": "Jupiter",
   "Distance": "628 million"
 },
 {
   "Planet": "Saturn",
   "Distance": "1,3 billion"
 },
 {
   "Planet": "Uranus",
   "Distance": "2,7 billion"
 },
 {
   "Planet": "Neptune",
   "Distance": "4, 3 billion"
 }
]


function getDistanceNumber(Planet) {
  return data.filter(
      function(data){return data.Planet == Planet}
  );
}

var found = getDistanceNumber('Mars');

document.getElementById('output').innerHTML=found[0].Distance;

<div id="output"></div>

Answer 1

请注意，我对数据进行了一些相当微不足道的更新。我在用着 ”。”而不是“，”作为小数点分隔符。我还删除了海王星距离中的额外空间，因为它看起来像是数据输入中的错字。

---

我将其分解为更小的问题。 即……

• 将距离字符串转换成数值，
• 从名称字符串中获取行星的对象，
• 计算到输入的距离，
• 找到最小的距离，然后
• 使用最小距离的索引找到相应行星的名称。

console.clear()

// conver million/billion to numbers (in millions)
var conversionLUT = {'million': 1, 'billion': 1e3}

// convert distance string to number
function convertDistance(distStr){
  let dist = distStr.split(" ")
  return dist[0]*conversionLUT[dist[1]] || 0
}

// returns callback to calculate distance for a given planet
function distanceFrom(planetObj){
  return function(elem){
    return Math.abs(convertDistance(elem.Distance) - convertDistance(planetObj.Distance))
  }
}

// get object from array by planet name
function getPlanetObject(planetName, dat = data){
  return dat.find(d=>d.Planet === planetName)
}

// As one function
function findClosestPlanet(name, dat = data){
  // get distances given planet object
  let distances = dat.map(distanceFrom(getPlanetObject(name)))
  
  // smallest distance (filter out 0 to ignore self)
  let distToClosest = Math.min(...distances.filter(d => d>0))
  
  // find index of planet whose closest dist matches
  let indOfClosest = distances.findIndex(d=>d===distToClosest)
  
  // return planet name that is closest
  return data[indOfClosest].Planet
}

var data = [
 {
   "Planet": "Mercury",
   "Distance": "-92 million"
 },
 {
   "Planet": "Venus",
   "Distance": "-42 million"
 },
 {
   "Planet": "Earth",
   "Distance": "0"
 },
 {
   "Planet": "Mars",
   "Distance": "78 million"
 },
 {
   "Planet": "Jupiter",
   "Distance": "628 million"
 },
 {
   "Planet": "Saturn",
   "Distance": "1.3 billion"
 },
 {
   "Planet": "Uranus",
   "Distance": "2.7 billion"
 },
 {
   "Planet": "Neptune",
   "Distance": "4.3 billion"
 }
]

document.getElementById('output').innerHTML = findClosestPlanet('Saturn')

<div id="output"></div>