Thread by @swapnakpanda

7️⃣ Unique Features of JavaScript 🔥

Are you new to JavaScript? Know about these 7 features that are rare in other programming languages.

🧵 👇

1️⃣ undefined
2️⃣ Functions as first-class citizens
3️⃣ Closure
4️⃣ Prototypal Inheritance
5️⃣ Divide by Zero doesn't result into error
6️⃣ Array-Like
7️⃣ Strings are primitives

1️⃣ undefined

✪ Almost all languages have a special empty value which is called null, Null, None etc

✪ In addition to null, JavaScript also has one more: undefined

✪ If something is not known to exist, use "undefined". If something exists but its value is unknown, use "null"

2️⃣ Functions as first-class citizens

In JavaScript,

✪ Functions can be treated as values, i.e. can be stored as a value in a variable

✪ Functions can be passed as arguments to another function

✪ Functions can be returned from another function

Hence, first-class citizen.

3️⃣ Closure

✪ Variables can have scopes to be accessed inside a function only.

✪ Because functions are first-class citizens, an inner function can be defined inside any function.

✪ The inner function can access variables scoped to parent function which is known as "Closure"

4️⃣ Prototypal Inheritance

✪ All JavaScript objects inherit properties and methods from a prototype

✪ Prototype itself is an object which may inherit from another prototype

✪ When we read a property from object, and it's missing; it automatically takes it from the prototype

5️⃣ Divide by Zero doesn't result into error

✪ Many languages throw error when a number is attempted to be divided by Zero.

✪ But, JavaScript handles it other way. It results into NaN, Infinity or, -Infinity.

✪ Example

0 / 0 ⇨ NaN
1 / 0 ⇨ Infinity
-1/0 ⇨ -Infinity

6️⃣ Array-Like

✪ If an object has a "length" property and can be iterated, that's known as "Array-Like".

✪ If an object is "Array-Like", it can be used like an Array in many use cases.

✪ Example: strings are "Array-Like".

7️⃣ Strings are primitives

✪ Unlike many other languages, JavaScript treats strings as primitives. Where needed strings are auto converted to objects.

✪ Though there are ways to create Strings as Objects, but it's unnecessary and not recommended.

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