----- Why we use meta tags? ------

In HTML, meta tags are used to provide metadata about a document. Commonly used meta tags include those that define the character set (), set the viewport for responsive design (), and provide information for search engines ().

----- Difference between pseudo class and pseudo elements in css -----

Pseudo-classes enable you to target an element when it's in a particular state, as if you had added a class for that state to the DOM. Pseudo-elements act as if you had added a whole new element to the DOM, and enable you to style that.

(Pseudo-classes are used to style elements based on their state or position in the document) (Pseudo-elements allow you to style specific parts of an element, such as the first line or first letter.)

----- Difference beetwen Mixin and Extend in css -----

1 - A mixin is a way to group and reuse a set of CSS declarations.

@mixin border-radius($radius) { border-radius: $radius; }

// Using the mixin .box { @include border-radius(5px); }

.button { @include border-radius(10px); }

2 - Extend is a feature that allows one selector to inherit the styles of another.

.base-style { color: blue; font-size: 16px; }

.header { @extend .base-style; font-weight: bold; }

----- JS Data Types -----

1 -- Primitive ( string, number, boolean, undefined, null, symbol, BigInt) -(Single value) 2 -- Reference (Object(object, array, function...etc)) -(multiple value)

----- JS Variables difference -----

let myNumber = 42; Ozgaradigan o'zgaruvchi var smth = true; Global o'zgaruvchi const str = 81; O'zgarmaydigan o'zgaruvchi

----- Number methods in JS -----

Number() parseInt() parseFloat()

----- Math object in JS -----

The Math object in JavaScript provides a set of properties and methods for mathematical operations. Here are some commonly used features of the Math object:

Math Constants:

Math.PI: Represents the mathematical constant Pi (π). Math.E: Represents the mathematical constant Euler's number (e).

Math Methods:

Math.abs(x): Returns the absolute value of a number. Math.sqrt(x): Returns the square root of a number. Math.pow(x, y): Returns the value of x to the power of y. Math.floor(x): Returns the largest integer less than or equal to a given number. Math.ceil(x): Returns the smallest integer greater than or equal to a given number. Math.round(x): Returns the value of a number rounded to the nearest integer. Math.random(): Returns a pseudo-random number between 0 (inclusive) and 1 (exclusive).

----- String methods -----

length: Returns the length of a string.

let str = "Hello, World!"; console.log(str.length); // Output: 13

toUpperCase and toLowerCase:

toUpperCase(): Converts the string to uppercase. toLowerCase(): Converts the string to lowercase.

let str = "JavaScript"; console.log(str.toUpperCase()); // Output: "JAVASCRIPT" console.log(str.toLowerCase()); // Output: "javascript"

trim(): Removes whitespace from both ends of a string.

----- Difference between undifined and null -----

undefined means a variable has been declared but has not yet been assigned a value, whereas null is an assignment value, meaning that a variable has been declared and given the value of null .

----- Truthy, Falthy ------

In JavaScript, values are categorized as either "truthy" or "falsy" when evaluated in a boolean context (such as an if statement or as a condition in a loop). Understanding truthy and falsy values is important for writing conditional logic.

Falsy values: Values that are considered falsy when coerced to a boolean are:

false: The boolean value false. 0: The number zero. -0: Negative zero. 0n: BigInt zero. "": An empty string. null: The absence of a value. undefined: A variable that has not been assigned a value. NaN: Not a Number.

Truthy values: Values that are considered truthy when coerced to a boolean are:

true: The boolean value true. Any non-zero number (including negative numbers and decimals). Any non-empty string. An object (including arrays and functions). The special value Infinity. The special value -Infinity. The special value NaN (though it's generally better to avoid relying on NaN truthiness).