Javascript - 从对象中删除未定义的字段 [英] Javascript - removing undefined fields from an object
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问题描述
是否有一种干净的方法可以从对象中删除未定义的字段?
Is there a clean way to remove undefined fields from an object?
即
> var obj = { a: 1, b: undefined, c: 3 }
> removeUndefined(obj)
{ a: 1, c: 3 }
我遇到了两个解决方案:
I came across two solutions:
_.each(query, function removeUndefined(value, key) {
if (_.isUndefined(value)) {
delete query[key];
}
});
或:
_.omit(obj, _.filter(_.keys(obj), function(key) { return _.isUndefined(obj[key]) }))
推荐答案
使用 ES6 箭头功能和三元运算符的单线:
A one-liner using ES6 arrow function and ternary operator:
Object.keys(obj).forEach(key => obj[key] === undefined ? delete obj[key] : '');
或使用短路评估而不是三元评估:( @Matt Langlois ,感谢您的信息!)
Or use short-circuit evaluation instead of ternary: (@Matt Langlois, thanks for the info!)
Object.keys(obj).forEach(key => obj[key] === undefined && delete obj[key])
使用if表达式的相同示例:
Same example using if expression:
Object.keys(obj).forEach(key => {
if (obj[key] === undefined) {
delete obj[key];
}
});
如果你想删除 null
,''
和 undefined
,请使用!obj [key]
代替 obj [key] === undefined
。
If you want to remove null
, ''
and undefined
, use !obj[key]
instead of obj[key] === undefined
.
如果你想从嵌套对象中删除项目,可以使用递归函数:
If you want to remove the items from nested objects as well, you can use a recursive function:
const removeEmpty = (obj) => {
Object.keys(obj).forEach(key => {
if (obj[key] && typeof obj[key] === 'object') removeEmpty(obj[key]);
else if (obj[key] === undefined) delete obj[key];
});
return obj;
};
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