Feb 17 · 3 min read · undefined == null → true, but null == 0 → false (WHY?) JavaScript equality is one of the most confusing topics for beginners. Consider these three statements: undefined == null // true undefined === null // false null == 0 // false At...
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Aug 20, 2025 · 2 min read · Si alguna vez te has encontrado con null y undefined en JavaScript y te has preguntado cuáles son las diferencias reales entre ambos, no estás solo. Estos conceptos pueden ser confusos al principio, pero una vez que conoces sus particularidades, se v...
Join discussionJul 12, 2025 · 4 min read · Purpose I wrote this article to clear up confusion about null and undefined, so we can be better prepared for interview questions. These are very basic concepts in JavaScript, but they often cause confusion, especially for beginners. Introduction As...
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May 23, 2025 · 5 min read · If you're new to JavaScript (or even experienced), undefined, null, and NaN can feel like three very confusing cousins.They all seem to mean "nothing" — but they're very different kinds of nothing. Let’s clear it all up, once and for all. 1️⃣ undefi...
Join discussionApr 15, 2025 · 4 min read · 🔍 null vs undefined – Deep Dive ✅ Quick Overview Table Featurenullundefined Typeobject (bug!)undefined IntentIntentional absenceValue not yet assigned Default by JS?NoYes (automatically by JS engine) Common UseEmpty, cleared, or missing va...
Join discussionFeb 12, 2025 · 9 min read · When learning JavaScript, one of the fundamental concepts to understand is data types. Data types define the kind of values a variable can hold. JavaScript is a dynamically typed language, meaning you don't need to specify a variable's type when decl...
Join discussionDec 29, 2024 · 3 min read · Understanding null and undefined in JavaScript In JavaScript, handling missing or unknown values is common. To manage such scenarios, JavaScript provides two special values: null and undefined. Although they may seem similar at first glance, they ser...
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Nov 25, 2024 · 1 min read · 定义zod schema的时候，有时候定义为nullable时要注意：如果你是从一个可能为空的对象里取出一个字段来parse的时候，可能会出现问题： const schema = z.object({ a: z.string().nullable() }); const rawData = { nested: null }; const data = schema.parse({ a: rawData.nested?.a }); 会导致throw，程序无法继续下去。 解决办法：...
Join discussionAug 23, 2024 · 3 min read · TL;DR The bang operator tells the compiler to temporarily relax the "not null" constraint that it might otherwise demand. It says to the compiler: "As the developer, I know better than you that this variable cannot be null right now". I think this qu...
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May 26, 2024 · 3 min read · JavaScript is a versatile and powerful language, but it comes with some concepts that can be tricky to understand. In this blog, we’ll explore three important concepts: hoisting, the this keyword, and the difference between undefined and not defined....
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