JavaScript: Create an object composed of the properties the given function returns falsey for
JavaScript: Exercise-154 with Solution
Write a JavaScript program to create an object composed of the properties the given function returns false for. The function is invoked with two arguments: (value and key).
- Use Object.keys() and Array.prototype.filter() to remove the keys for which fn returns a truthy value.
- Use Array.prototype.reduce() to convert the filtered keys back to an object with the corresponding key-value pairs.
- The callback function is invoked with two arguments: (value, key).
Sample Solution:
JavaScript Code:
//#Source https://bit.ly/2neWfJ2
const omitBy = (obj, fn) =>
Object.keys(obj)
.filter(k => !fn(obj[k], k))
.reduce((acc, key) => ((acc[key] = obj[key]), acc), {});
console.log(omitBy({ a: 1, b: '2', c: 3 }, x => typeof x === 'number'));
Sample Output:
{"b":"2"}
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-154-1 by w3resource (@w3resource) on CodePen.
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Next: Write a JavaScript program that takes a predicate and array, like Array.filter(), but only keeps x if pred(x) returns false.
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