同时映射和过滤数组 [英] Map and filter an array at the same time

问题描述

我有一个对象数组，我想对其进行迭代以生成新的过滤数组.而且，我需要根据参数从新数组中过滤掉一些对象.我正在尝试:

function renderOptions(options) {返回 options.map(function (option) {如果(！option.assigned){返回(一些新对象)；}});}

这是一个好方法吗?有没有更好的方法?我愿意使用任何库，例如 lodash.

解决方案

你应该使用 Array.reduce 为此.

var options = [{名称:'一'，分配:真}，{名称:'二'，分配:假}，{名称:'三'，分配:真}，];var 减少 = options.reduce(function(filtered, option) {如果(选项.分配){var someNewValue = { name: option.name, newProperty: 'Foo' }过滤推(someNewValue)；}返回过滤；}, []);document.getElementById('output').innerHTML = JSON.stringify(reduced);

仅分配选项
<pre id="输出">

<小时>

或者，reducer 可以是一个纯函数，像这样

var reduction = options.reduce(function(result, option) {如果(选项.分配){返回结果.concat({名称:option.name，新属性:'Foo'});}返回结果；}, []);

I have an array of objects that I want to iterate over to produce a new filtered array. But also, I need to filter out some of the objects from the new array depending of a parameter. I'm trying this:

function renderOptions(options) {
    return options.map(function (option) {
        if (!option.assigned) {
            return (someNewObject);
        }
    });   
}

Is that a good approach? Is there a better method? I'm open to use any library such as lodash.

解决方案

You should use Array.reduce for this.

var options = [
  { name: 'One', assigned: true }, 
  { name: 'Two', assigned: false }, 
  { name: 'Three', assigned: true }, 
];

var reduced = options.reduce(function(filtered, option) {
  if (option.assigned) {
     var someNewValue = { name: option.name, newProperty: 'Foo' }
     filtered.push(someNewValue);
  }
  return filtered;
}, []);

document.getElementById('output').innerHTML = JSON.stringify(reduced);

<h1>Only assigned options</h1>
<pre id="output"> </pre>

---

Alternatively, the reducer can be a pure function, like this

var reduced = options.reduce(function(result, option) {
  if (option.assigned) {
    return result.concat({
      name: option.name,
      newProperty: 'Foo'
    });
  }
  return result;
}, []);

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