Feb 7, 2013 · var checkProp = function(obj, prop, val){ obj[prop] = obj[prop] || val; // If obj[prop] exists, set it to itself (does nothing), otherwise, set it's content to `val`. console.log(obj.prop); }; Share

Apr 4, 2016 · If you are looking for a property defined in an object, you can use hasOwnProperty method of the object. like this: myObject = new MyObject(); // some code if ( myObject.hasOwnProperty('prop') ) { // prop exists }

Nov 18, 2023 · In this article, we will dive deep into various methods used for object validation in JavaScript. We’ll explain each method, its importance, practical use cases, and provide comprehensive...

May 13, 2011 · What is the best way to test the integrity of a complex object in JavaScript? My object has a bunch of different variables, some optional, some required. The correct structure is vital to the code's functionality, but if I make a mistake during the definition, finding the exact value that caused the problem could get very tedious.

Aug 24, 2019 · In this blog post, we’re going to implement a JavaScript object validator using TDD. TDD flips a lot of “conventional” software development processes upside-down by writing tests first and then writing code that will satisfy those tests.

Feb 14, 2025 · Learn how to write a null check function in JavaScript and explore the differences between the null and undefined attributes.

Aug 28, 2024 · By this operator, we will learn how to check for null values in JavaScript by the (===) operator. This operator only passes for null values, not for undefined, false, 0, NaN. Syntax: x === y; Example: The following code snippets show some comparison of objects. JavaScript

Nov 10, 2023 · There are several strategies to check if a value is an object. The primary reason is that in JavaScript, any non-primitive type (primitives: string, number, bigint, boolean, undefined, symbol, and null) is treated as an object, but depending on the checking method, there are considerations to take into account.

JavaScript Object.groupBy() ES2024 added the Object.groupBy() method to JavaScript. The Object.groupBy() method groups elements of an object according to string values returned from a callback function. The Object.groupBy() method does not change the original object.

Jul 15, 2009 · JavaScript has instanceof and typeof that can help you check what kind of objects are being passed to your functions: You can use these to set some default "bad" values for your instance variables: foo = foo instanceof Array ? foo : []; // If 'foo' is not an array, make it an empty one. bar = bar instanceof Number ? bar : 0;