按属性排序数组

Question

我现在只需获取数组的前3个对象并映射它们:

<ul className="ItemSearchList"> 
  { 
    champions.slice(0,3).map(function(champ){
      return (
        <li key={champ.id} >
          <div className="media">
            <div className="media-left">
              <a href="#">
                <img className="media-object" src={"http://ddragon.leagueoflegends.com/cdn/5.2.1/img/champion/" + champ.key  + ".png"} />
              </a>
            </div>
            <div className="media-body" >
              <h4 className="media-heading">{champ.name}</h4>
              <div>
                something
              </div>
            </div>
          </div>
        </li>
      )
    }) 
  }
</ul>

每个champ都有一个level属性(champ.level).

如何将输出排序到champ.level descending切片前3？

Answer 1

使用Array.prototype.sort()自定义比较函数首先执行降序排序:

champions.sort(function(a, b) { return b.level - a.level }).slice(...

ES6甚至更好:

champions.sort((a, b) => b.level - a.level).slice(...

Answer 2

编写自己的比较函数:

function compare(a,b) {
  if (a.level < b.level)
     return -1;
  if (a.level > b.level)
    return 1;
  return 0;
}

要使用它:

champions.sort(compare).slice(0,3).map(function(champ) {

Answer 3

The pure JS solutions are nice. But if your project is set up via npm, you can also use Lodash or Underscore. In many cases those are already sub-dependencies so no extra weight is incurred.

Combining ES6 and _.orderBy provided by lodash

_.orderBy(champions, [c => c.level], ['desc']).slice(0,3)

This is a powerful little utility. You can provide multiple tie-breaking sort keys to orderBy, and specify an order for each individually.