How to filter keys of an object with lodash?
JavascriptFilterLodashJavascript Problem Overview
I have an object with some keys, and I want to only keep some of the keys with their value?
I tried with filter:
const data = {
aaa: 111,
abb: 222,
bbb: 333
};
const result = _.filter(data, (value, key) => key.startsWith("a"));
console.log(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>
But it prints an array:
> [111, 222]
Which is not what I want.
How to do it with lodash? Or something else if lodash is not working?
Javascript Solutions
Solution 1 - Javascript
Lodash has a _.pickBy function which does exactly what you're looking for.
var thing = {
"a": 123,
"b": 456,
"abc": 6789
};
var result = _.pickBy(thing, function(value, key) {
return _.startsWith(key, "a");
});
console.log(result.abc) // 6789
console.log(result.b) // undefined
<script src="https://cdn.jsdelivr.net/lodash/4.16.4/lodash.min.js"></script>
Solution 2 - Javascript
Just change filter to omitBy
const data = { aaa: 111, abb: 222, bbb: 333 };
const result = _.omitBy(data, (value, key) => !key.startsWith("a"));
console.log(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>
Solution 3 - Javascript
Here is an example using lodash 4.x:
const data = {
aaa: 111,
abb: 222,
bbb: 333
};
const result = _.pickBy(data, (value, key) => key.startsWith("a"));
console.log(result);
// Object { aaa: 111, abb: 222 }
Solution 4 - Javascript
A non-lodash way to solve this in a fairly readable and efficient manner:
function filterByKeys(obj, keys = []) {
const filtered = {}
keys.forEach(key => {
if (obj.hasOwnProperty(key)) {
filtered[key] = obj[key]
}
})
return filtered
}
const myObject = {
a: 1,
b: 'bananas',
d: null
}
const result = filterByKeys(myObject, ['a', 'd', 'e'])
console.log(result) // {a: 1, d: null}
Solution 5 - Javascript
Native ES2019 one-liner
const data = {
aaa: 111, abb: 222, bbb: 333 };
const filteredByKey = Object.fromEntries(Object.entries(data).filter(([key, value]) => key.startsWith("a")))
console.log(filteredByKey);
Solution 6 - Javascript
const data = {
aaa: 111,
abb: 222,
bbb: 333
};
const result = Object.keys(data).filter((val) => val.includes("a"));
console.log(result);
Solution 7 - Javascript
You can use the _.omit() function.
it accepts the keys to filter as an string array like below:
var object = { a: 1, b: 2, c: 3 }
_.omit(object, ['a', 'c'])
// => { b: 2 }
Solution 8 - Javascript
Pure JS solution:
const data = {
aaa: 111,
abb: 222,
bbb: 333
};
const result = Object.keys(data).filter( key => {
return key.indexOf('a') == 0
}).map( key => {
return { key: data[key] }
})
console.log(result)
- Filter through the data for keys that starts with the letter 'a'
- Map those keys with the proper value, and return as key:value object