JavaScript : Filter an array of objects based on a condition while also filtering out unspecified keys
JavaScript fundamental (ES6 Syntax): Exercise-98 with Solution
Write a JavaScript program to filter an array of objects based on a condition while also filtering out unspecified keys.
- Use Array.prototype.filter() to filter the array based on the predicate fn so that it returns the objects for which the condition returned a truthy value.
- On the filtered array, use Array.prototype.map() to return the new object.
- Use Array.prototype.reduce() to filter out the keys which were not supplied as the keys argument.
Sample Solution:
JavaScript Code:
//#Source https://bit.ly/2neWfJ2
const reducedFilter = (data, keys, fn) =>
data.filter(fn).map(el =>
keys.reduce((acc, key) => {
acc[key] = el[key];
return acc;
}, {})
);
const data = [
{
id: 1,
name: 'john',
age: 24
},
{
id: 2,
name: 'mike',
age: 50
}
];
console.log(reducedFilter(data, ['id', 'name'], item => item.age > 24));
Sample Output:
[{"id":2,"name":"mike"}]
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-98-1 by w3resource (@w3resource) on CodePen.
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Previous: Write a JavaScript program to create an object composed of the properties the given function returns truthy for. The function is invoked with two arguments: (value, key).
Next: Write a JavaScript program to hash an given input string into a whole number.
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JavaScript: Tips of the Day
Chunks an array into n smaller arrays
Example:
const tips_chunkIntoN = (arr, n) => { const size = Math.ceil(arr.length / n); return Array.from({ length: n }, (v, i) => arr.slice(i * size, i * size + size) ); } console.log(tips_chunkIntoN([1, 2, 3, 4, 5, 6, 7,8], 4));
Output:
[[1,2],[3,4],[5,6],[7,8]]
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