I wrote a customozer function to omit the undefined values of the object with cloneDeepWith
. However on the immutable return, it is not digging in recursively. Here is my code:
import { cloneDeepWith, pickBy, omit } from 'lodash';
const obj = {
a0: true,
b0: true,
c0: undefined,
obj1: {
a1: true,
b1: true,
c1: undefined
}
};
cloneDeepWith(obj, value => {
const objWithUndefinedValue = pickBy(obj, (value) => value === undefined);
const keysWithUndefinedValue = Object.keys(objWithUndefinedValue);
return omit(obj, keysWithUndefinedValue);
});
However it doesn't recurse after the first return. Is it possible to accomplish this with lodash stock functionality?
Lodash helps in working with arrays, strings, objects, numbers, etc. The _. isNil() method is used to check if the value is null or undefined. If the value is nullish then returns true otherwise it returns false.
The _. cloneDeep() method is used to create a deep copy of the value i.e. it recursively clones the value.
isUndefined() method is used to find whether the given value is undefined or not. It returns True if the given value is undefined. Otherwise, it returns false.
get() method in Lodash retrieves the object's value at a specific path. If the value is not present at the object's specific path, it will be resolved as undefined . This method will return the default value if specified in such a case.
As far as I know _.cloneDeepWith()
customizer is a bit misleading. The customizer should handle only non object values. If it handles object values, it should also continue the recursion by itself. For example, you can see that as the customizer is called, the cloning is handled by value.cloneNode(true)
. As you can see only body
appears in the console.
const { cloneDeepWith, isObject } = _;
function customizer(value) {
console.log(value);
if (_.isElement(value)) {
return value.cloneNode(true);
}
}
var el = _.cloneDeepWith(document.body, customizer);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
However, if you just customize non object values, and return undefined
for object values, which prompts the method to handle them (documented in cloneDeep), it iterates everything:
const { cloneDeepWith, isObject, isUndefined } = _;
const obj = {
a0: true,
b0: true,
c0: undefined,
obj1: {
a1: true,
b1: true,
c1: undefined
}
};
const result = cloneDeepWith(obj, v => {
console.log(v);
return isObject(v) ? undefined : 'custom value';
});
console.log(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
To solve your problem, you can use _.transform()
recursively to take all values that are not undefined
:
const { transform, isObject, isUndefined } = _;
const obj = {
a0: true,
b0: true,
c0: undefined,
obj1: {
a1: true,
b1: true,
c1: undefined
}
};
const cloneDeepWithoutUndefined = (obj) =>
transform(obj, (r, v, k) => {
if(isUndefined(v)) return;
r[k] = isObject(v) ? cloneDeepWithoutUndefined(v) : v;
});
const result = cloneDeepWithoutUndefined(obj);
console.log(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
This can be solved by using recursively lodash transform method via:
const obj = { a0: true, b0: true, c0: undefined, obj1: { a1: true, b1: true, c1: undefined } };
const cloneMe = (obj) => _.transform(obj, (r, v, k) =>
_.isUndefined(v) ? null : _.isObject(v) ? r[k] = cloneMe(v) : r[k] = v, {})
console.log(cloneMe(obj))
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>
You could also do this in ES6 only via Object.entries & reduce:
const obj = { a0: true, b0: true, c0: undefined, obj1: { a1: true, b1: true, c1: undefined } };
const cloneMe = (obj) => {
return Object.entries(obj).filter(([k,v]) =>
v != undefined).reduce((r,[k,v]) => {
r[k] = (v instanceof Object) ? cloneMe(v) : v
return r
},{})
}
console.log(cloneMe(obj))
You can additionally extend the check for object if instance of Object
is not sufficient etc.
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