Implementing filter() for JavaScript Objects

p.pogosov · November 12, 2024, 7:53pm

While ECMAScript 5 features a filter() method for Array objects, it seems there’s no such method for Object types. I’m curious about how to create a filter() function specifically for Objects in JavaScript. For instance, given the following object:

var sampleObject = { propertyOne: ‘Yes’ };

I’d like to write a filter() function that can be applied to objects, similar to the one below:

Object.prototype.filterProperties = function(condition) { var result = {}; for (const key in this) { if (this.hasOwnProperty(key) && !condition(this[key])) { result[key] = this[key]; } } return result; };

This implementation works in a demonstration, yet when added to my jQuery 1.5 and jQuery UI 1.8.9 project, it results in JavaScript errors appearing in FireBug. Any suggestions?

RustyCanoe · November 17, 2024, 3:46am

You can filter JavaScript objects by using Object.entries() to convert the object to an array, filter that array, and then convert it back to an object:


function filterObject(obj, callback) {
    return Object.fromEntries(
        Object.entries(obj).filter(([key, value]) => callback(key, value))
    );
}

Example usage:


const myObj = { a: 1, b: 2, c: 3 };
const filteredObj = filterObject(myObj, (key, value) => value > 1);
// filteredObj will be { b: 2, c: 3 }