Pull values from array based on function
JavaScript, Array · Oct 22, 2020
Mutates the original array to filter out the values specified, based on a given iterator function.
- Check if the last argument provided is a function.
- Use
Array.prototype.map()to apply the iterator functionfnto all array elements. - Use
Array.prototype.filter()andArray.prototype.includes()to pull out the values that are not needed. - Set
Array.prototype.lengthto mutate the passed in an array by resetting its length to0. - Use
Array.prototype.push()to re-populate it with only the pulled values.
const pullBy = (arr, ...args) => {
const length = args.length;
let fn = length > 1 ? args[length - 1] : undefined;
fn = typeof fn == 'function' ? (args.pop(), fn) : undefined;
let argState = (Array.isArray(args[0]) ? args[0] : args).map(val => fn(val));
let pulled = arr.filter((v, i) => !argState.includes(fn(v)));
arr.length = 0;
pulled.forEach(v => arr.push(v));
};var myArray = [{ x: 1 }, { x: 2 }, { x: 3 }, { x: 1 }];
pullBy(myArray, [{ x: 1 }, { x: 3 }], o => o.x); // myArray = [{ x: 2 }]
