在javascript

Question

我有一个包含键和数据的对象。我想从钥匙中获得上一个物品。

我以前见过类似的话题，但是解决方案确实很复杂。

我还添加了一个不起作用的功能，但我希望它能如何工作

简化代码

let obj = {
  slug:        'my-page',
  title:       'My title',
  description: 'My description',
  content:     'My content'
};

let previous = obj.previousItem('description'); // Does not work

console.log(previous);

预期结果

  

{标题：“我的标题”   }

• ES5甚至ES6都很好
• 相对于复杂的解决方案，我更喜欢简单的解决方案，也许没有循环

Answer 1

对象以前是没有顺序的，但实际上它们是有顺序的，我不会依赖此顺序。

但是无论如何，您都可以按下一个键/值对进行过滤并获得一个对象。

let obj = { slug: 'my-page', title: 'My title', description: 'My description', content: 'My content' },
    previous = Object.fromEntries(Object
        .entries(obj)
        .filter((_, i, { [i + 1]: next = [] }) => next[0] === 'description')
    );

console.log(previous);

Answer 2

我认为是这样

Object.prototype.previousItem = function(propName) {
  const arr = Object.keys(this);
  let indx = arr.indexOf(propName)-1;
  if (indx<0) return null;
  const result = {};
  result[arr[indx]] = this[arr[indx]];
  return result;
}

Answer 3

    <?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Cooperado;

class CooperadoController extends Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        //
        //$cooperados = Cooperado::all();
        $cooperados = Cooperado::orderBy('dtCad', 'desc')->paginate(10);
        return view('cooperados.index', compact('cooperados'));
    }

    /**
     * Show the form for creating a new resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function create()
    {
        //
        return view('cooperados.create');
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function store(Request $request)
    {
        //
        $request->validate([
            'nameCoop'=>'required',
            'numCoop'=> 'required|integer',
            'cpfCoop'=> 'required',
            'dtCad'=>'required|date',
            'subscritas'=>'required'
          ]);
          $cooperado = new Cooperado([
            'nameCoop' => $request->get('nameCoop'),
            'numCoop'=> $request->get('numCoop'),
            'cpfCoop'=> $request->get('cpfCoop'),
            'dtCad'=> $request->get('dtCad'),
            'description'=> $request->get('description'),
            'subscritas'=> $request->get('subscritas'),
            'aintegralizar'=> $request->get('subscritas'),
            'status'=> $request->get('status')
          ]);
          $cooperado->save();
          return redirect('/cooperados')->with('success', 'Cooperado adicionado');
    }

    /**
     * Display the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function show($id)
    {
        //
        $cooperado = Cooperado::find($id);
        return view('cooperados.show', compact('cooperado'));
    }

    /**
     * Show the form for editing the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function edit($id)
    {
        //
        $cooperado = Cooperado::find($id);

        return view('cooperados.edit', compact('cooperado'));
    }

    /**
     * Update the specified resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, $id)
    {
        //
        $request->validate([
            'nameCoop'=>'required',
            'numCoop'=> 'required|integer',
            'cpfCoop'=> 'required',
            'dtCad'=>'required|date',
            'subscritas'=>'required'
          ]);

          $cooperado = Cooperado::find($id);
          $cooperado->nameCoop = $request->get('nameCoop');
          $cooperado->numCoop = $request->get('numCoop');
          $cooperado->cpfCoop = $request->get('cpfCoop');
          $cooperado->dtCad = $request->get('dtCad');
          $cooperado->dtDem = $request->get('dtDem');
          $cooperado->description = $request->get('description');
          $cooperado->subscritas = $request->get('subscritas');
          $cooperado->integralizadas = $request->get('integralizadas');
          $cooperado->aintegralizar = $request->get('aintegralizar');
          $cooperado->status = $request->get('status');
          $cooperado->save();

          return redirect('/cooperados')->with('success', 'Cooperado atualizado');
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function destroy($id)
    {
        //
    $cooperado = Cooperado::find($id);
    $cooperado->delete();

    return redirect('/cooperados')->with('success', 'Sucess');
    }
}

Answer 4

您可以尝试按照以下操作获得上一项

let object = {
    slug: 'my-page',
    title: 'My title',
    description: 'My description',
    content: 'My content'
}
let previous = previousItem(object, 'description');
console.log(previous);


function previousItem(object, str) {
    let lastKey = "";

    for (const key in object) {
        if (object.hasOwnProperty(key)) {
            if (key == str){
                lastKey = lastKey || key;
                let obj = { };
                obj[lastKey] = object[lastKey];
                return obj;
            } else {
                lastKey = key;
            }
        }
    }
}