如何删除JavaScript对象中未定义或空的所有属性?

(这个问题与数组的问题类似)


当前回答

使用Nullish合并可用ES2020

const filterNullishPropertiesFromObject = (obj) => {
  const newEntries = Object.entries(obj).filter(([_, value]) => {
    const nullish = value ?? null;
    return nullish !== null;
  });

  return Object.fromEntries(newEntries);
};

其他回答

Oneliner:

let obj = { a: 0, b: "string", c: undefined, d: null };

Object.keys(obj).map(k => obj[k] == undefined ? delete obj[k] : obj[k] );

控制台.log(卷);

Obj将是{a: 0, b: "string"}

如果你想要4行纯ES7解决方案:

const clean = e => e instanceof Object ? Object.entries(e).reduce((o, [k, v]) => {
  if (typeof v === 'boolean' || v) o[k] = clean(v);
  return o;
}, e instanceof Array ? [] : {}) : e;

或者如果你喜欢更易读的版本:

function filterEmpty(obj, [key, val]) {
  if (typeof val === 'boolean' || val) {
    obj[key] = clean(val)
  };

  return obj;
}

function clean(entry) {
  if (entry instanceof Object) {
    const type = entry instanceof Array ? [] : {};
    const entries = Object.entries(entry);

    return entries.reduce(filterEmpty, type);
  }

  return entry;
}

这将保留布尔值,也将清理数组。它还通过返回一个清理过的副本来保存原始对象。

递归地删除null, undefined,空对象和空数组,返回一个副本(ES6版本)

export function skipEmpties(dirty) {
    let item;
    if (Array.isArray(dirty)) {
        item = dirty.map(x => skipEmpties(x)).filter(value => value !== undefined);
        return item.length ? item : undefined;
    } else if (dirty && typeof dirty === 'object') {
        item = {};
        Object.keys(dirty).forEach(key => {
            const value = skipEmpties(dirty[key]);
            if (value !== undefined) {
                item[key] = value;
            }
        });
        return Object.keys(item).length ? item : undefined;
    } else {
        return dirty === null ? undefined : dirty;
    }
}

你可以剪短一点!条件

var r = {a: null, b: undefined, c:1};
for(var k in r)
   if(!r[k]) delete r[k];

使用时请记住:as @分色announcement in comments:如果值为空字符串、false或0,这也会删除属性

你可以循环遍历对象:

Var检验= { test1:空, test2:“somestring”, test3: 3, } 函数clean(obj) { for (var propName in obj) { if (obj[propName] === null || obj[propName] === undefined) { 删除obj [propName]; } } 返回obj } console.log(测试); console.log(清洁(测试));

如果你担心这个属性删除不会运行到对象的proptype链,你还可以:

function clean(obj) {
  var propNames = Object.getOwnPropertyNames(obj);
  for (var i = 0; i < propNames.length; i++) {
    var propName = propNames[i];
    if (obj[propName] === null || obj[propName] === undefined) {
      delete obj[propName];
    }
  }
}

关于null和undefined的一些注意事项:

test.test1 === null; // true
test.test1 == null; // true

test.notaprop === null; // false
test.notaprop == null; // true

test.notaprop === undefined; // true
test.notaprop == undefined; // true