ECMAScript 5有数组类型的filter()原型,但没有对象类型,如果我理解正确的话。

我如何在JavaScript中实现对象的过滤器()?

假设我有这个对象:

var foo = {
    bar: "Yes"
};

我想写一个过滤器(),工作在对象:

Object.prototype.filter = function(predicate) {
    var result = {};

    for (key in this) {
        if (this.hasOwnProperty(key) && !predicate(this[key])) {
            result[key] = this[key];
        }
    }

    return result;
};

当我在下面的演示中使用它时,这是有效的,但是当我将它添加到使用jQuery 1.5和jQuery UI 1.8.9的站点时,我在FireBug中得到JavaScript错误。

Object.prototype.filter = function(predicate) { var result = {}; for (key in this) { if (this.hasOwnProperty(key) && !predicate(this[key])) { console.log("copying"); result[key] = this[key]; } } return result; }; var foo = { bar: "Yes", moo: undefined }; foo = foo.filter(function(property) { return typeof property === "undefined"; }); document.getElementById('disp').innerHTML = JSON.stringify(foo, undefined, ' '); console.log(foo); #disp { white-space: pre; font-family: monospace } <div id="disp"></div>


当前回答

我只是想添加我这样做的方式,因为它节省了我创建额外的函数,我认为更干净,我没有看到这个答案:

let object = {a: 1, b: 2, c: 3};
[object].map(({a,c}) => ({a,c}))[0]; // {a:1, c:2}

最酷的是,它也适用于对象数组:

let object2 = {a: 4, b: 5, c: 6, d: 7};
[object, object2].map(({a,b,c,d}) => ({a,c})); //[{"a":1,"c":3},{"a":4,"c":6}]
[object, object2].map(({a,d}) => ({a,d})); //[{"a":1,"d":undefined},{"a":4,"d":7}]

其他回答

如果你的对象中有Symbol属性,那也应该被过滤,你不能使用:object。键对象。Object.fromEntries,…因为:

符号键是不可枚举的!

你可以使用Reflect。reduce中的ownKeys和filter key

Reflect.ownKeys(o).reduce((a, k) => allow.includes(k) && {...a, [k]: o[k]} || a, {});

(打开DevTools输出日志- Stackoverflow界面上不记录符号)

const bKey =符号('b_k'); Const o = { 一个 : 1, [bKey ]: ' b”, C: [1,3], [Symbol.for (' d ')]: ' d ' }; const allow = ['a', bKey, Symbol.for('d')]; const z1 = Reflect.ownKeys(o)。Reduce ((a, k) => allow.includes(k) &&{…A, [k]: o[k]} || A, {}); console.log (z1);// {a: 1,符号(b_k): "b",符号(d): "d"} console.log(bKey in z1) // true console.log(Symbol.for('d') in z1) // true

这个等于这个

const z2 = Reflect.ownKeys(o).reduce((a, k) => allow.includes(k) && Object.assign(a, {[k]: o[k]}) || a, {});
const z3 = Reflect.ownKeys(o).reduce((a, k) => allow.includes(k) && Object.defineProperty(a, k, {value: o[k]}) || a, {});

console.log(z2); // {a: 1, Symbol(b_k): "b", Symbol(d): "d"}
console.log(z3); // {a: 1, Symbol(b_k): "b", Symbol(d): "d"}

在filter()函数中,可以传递一个可选的目标对象

const filter = (o, allow, t = {}) => Reflect.ownKeys(o).reduce(
    (a, k) => allow.includes(k) && {...a, [k]: o[k]} || a, 
    t
);

console.log(filter(o, allow));           // {a: 1, Symbol(b_k): "b", Symbol(d): "d"}
console.log(filter(o, allow, {e: 'e'})); // {a: 1, e: "e", Symbol(b_k): "b", Symbol(d): "d"}

ES6进近...

假设你有下面这个对象:

const developers = {
  1: {
   id: 1,
   name: "Brendan", 
   family: "Eich"
  },
  2: {
   id: 2,
   name: "John", 
   family: "Resig"
  },  
  3: {
   id: 3,
   name: "Alireza", 
   family: "Dezfoolian"
 }
};

创建一个函数:

const filterObject = (obj, filter, filterValue) => 
   Object.keys(obj).reduce((acc, val) => 
   (obj[val][filter] === filterValue ? acc : {
       ...acc,
       [val]: obj[val]
   }                                        
), {});

叫它:

filterObject(developers, "name", "Alireza");

并将返回:

{
  1: {
  id: 1,
  name: "Brendan", 
  family: "Eich"
  },
  2: {
   id: 2,
   name: "John", 
   family: "Resig"
  }
}
    var foo = {
    bar: "Yes",
    pipe: "No"
};

const ret =  Object.entries(foo).filter(([key, value])=> value === 'Yes');

https://masteringjs.io/tutorials/fundamentals/filter-object

如果您希望改变相同的对象,而不是创建一个新的对象。

下面的例子将删除所有0或空值:

const sev = { a: 1, b: 0, c: 3 };
const deleteKeysBy = (obj, predicate) =>
  Object.keys(obj)
    .forEach( (key) => {
      if (predicate(obj[key])) {
        delete(obj[key]);
      }
    });

deleteKeysBy(sev, val => !val);

就像所有人说的,不要在原型上做文章。相反,只需编写一个函数来执行此操作。以下是我使用lodash的版本:

import each from 'lodash/each';
import get from 'lodash/get';

const myFilteredResults = results => {
  const filteredResults = [];

  each(results, obj => {
    // filter by whatever logic you want.

    // sample example
    const someBoolean = get(obj, 'some_boolean', '');

    if (someBoolean) {
      filteredResults.push(obj);
    }
  });

  return filteredResults;
};