Angular SSR build Ensure Production Build (--prod flag)

 When you run npm run build:ssr, make sure it is performing the production build. Check your angular.json to verify that production optimizations are enabled for both the client and SSR build.

If you're running npm run build:ssr and it's not using the --prod flag, update your build configuration to include production optimizations.

In the angular.json, ensure you have the --prod flag set in the SSR build configuration:

"configurations": {

  "production": {

    "fileReplacements": [

      {

        "replace": "src/environments/environment.ts",

        "with": "src/environments/environment.prod.ts"

      }

    ],

    "optimization": true,

    "outputHashing": "all",

    "sourceMap": false,

    "extractCss": true,

    "namedChunks": false,

    "aot": true

  }

}

Update your build script (package.json), if necessary, to ensure ng build --prod is used. The build script for SSR may look like this:

json

Copy code

"scripts": {

  "build:ssr": "ng build --prod && ng run your-app-name:server:production"

}

Angular guards with example

Angular, guards are used to control access to certain routes based on conditions. They allow you to decide whether a user can navigate to a particular route or not, and they can also be used to execute some logic before entering or leaving a route.

There are four types of guards in Angular:

1. CanActivate - Determines if a route can be activated.

2. CanActivateChild - Determines if a child route can be activated.

3. CanDeactivate - Determines if the current route can be deactivated.

4. Resolve - Resolves data before a route is activated.

5. CanLoad - Determines if a route can be loaded, often used with lazy-loaded routes.

 

Sets, Relations, and Functions JavaScript with examples

Let's break down the concepts of sets, relations, and functions with examples in JavaScript.

Sets, Relations, and Functions:

1. Sets:

A set is a collection of well-defined objects or elements. These objects can be anything like numbers, letters, or even other sets. Sets are usually denoted by curly braces {}.

Example of a Set:

let A = {1, 2, 3, 4};  // Set A containing four elements
let B = {a, b, c};      // Set B containing three elements

Operations on Sets:

1. Union (A ∪ B): Combines elements from both sets.

   let A = {1, 2, 3};
   let B = {3, 4, 5};
   let union = new Set([...A, ...B]);  // Union of A and B
   console.log(union);  // Output: {1, 2, 3, 4, 5}
   

2. Intersection (A ∩ B): Finds elements common to both sets.

   let intersection = new Set([...A].filter(x => B.has(x)));
   console.log(intersection);  // Output: {3}
   

3. Difference (A - B): Elements in A that are not in B.

   let difference = new Set([...A].filter(x => !B.has(x)));
   console.log(difference);  // Output: {1, 2}
   

2. Relations:

A relation between two sets is a collection of ordered pairs where the first element is from the first set, and the second element is from the second set. In JavaScript, a relation can be represented as a set of pairs.

Example of a Relation:

Consider two sets:

• Set A = {1, 2, 3}
• Set B = {a, b, c}

A relation R from A to B can be represented as a set of ordered pairs:

let R = new Set([[1, 'a'], [2, 'b'], [3, 'c']]);
console.log(R);  // Output: Set { [ 1, 'a' ], [ 2, 'b' ], [ 3, 'c' ] }

Types of Relations:

1. Reflexive Relation: A relation R is reflexive if every element of set A is related to itself. For example, if A = {1, 2, 3}, then R = {(1, 1), (2, 2), (3, 3)} is reflexive.

2. Symmetric Relation: A relation R is symmetric if for every pair (a, b) in R, the pair (b, a) is also in R. Example: If (1, 2) is in R, then (2, 1) must also be in R.

3. Transitive Relation: A relation R is transitive if for all a, b, c ∈ A, whenever (a, b) and (b, c) are in R, then (a, c) must also be in R.

3. Functions:

A function is a special type of relation where each element in the domain (the first set) is related to exactly one element in the codomain (the second set). A function can be denoted as f: A → B, where A is the domain, and B is the codomain.

Example of a Function:

Let’s say:

• Set A = {1, 2, 3}
• Set B = {a, b, c}

A function f: A → B could be:

let f = new Map([
  [1, 'a'],  // f(1) = 'a'
  [2, 'b'],  // f(2) = 'b'
  [3, 'c']   // f(3) = 'c'
]);

console.log(f);  // Output: Map { 1 => 'a', 2 => 'b', 3 => 'c' }

Types of Functions:

1. One-to-One (Injective): A function is one-to-one if different elements of the domain map to different elements of the codomain. In our example, f is one-to-one because no two elements in A map to the same element in B.

2. Onto (Surjective): A function is onto if every element of the codomain has at least one element from the domain mapping to it. For instance, if B = {a, b, c} and f = {1 → a, 2 → b, 3 → c}, the function is onto because every element in B has a corresponding element in A.

3. One-to-One Correspondence (Bijective): A function is bijective if it is both one-to-one and onto, meaning there is a perfect pairing between the elements of the domain and codomain.

Example of a Bijective Function:

Let’s say:

• Set A = {1, 2, 3}
• Set B = {a, b, c}

A bijective function f: A → B could be:

let f = new Map([
  [1, 'a'],
  [2, 'b'],
  [3, 'c']
]);

console.log(f);  // Output: Map { 1 => 'a', 2 => 'b', 3 => 'c' }

In this case, the function is both injective and surjective, making it bijective.

Summary of Examples:

1. Set Operations (Union, Intersection, Difference)
2. Relation (Set of ordered pairs)
3. Function (Mapping of domain to codomain)

Sets, Relations, and Functions 

JavaScript calculation base examples

 Here are some examples of basic calculations in JavaScript:

1. Addition

let a = 5;
let b = 3;
let sum = a + b;

console.log(sum);  // Output: 8

2. Subtraction

let a = 10;
let b = 4;
let difference = a - b;

console.log(difference);  // Output: 6

3. Multiplication

let a = 6;
let b = 7;
let product = a * b;

console.log(product);  // Output: 42

4. Division

let a = 20;
let b = 4;
let quotient = a / b;

console.log(quotient);  // Output: 5

5. Modulus (Remainder)

let a = 15;
let b = 4;
let remainder = a % b;

console.log(remainder);  // Output: 3

6. Exponentiation

let a = 2;
let b = 3;
let power = a ** b;

console.log(power);  // Output: 8

7. Square Root

let a = 25;
let squareRoot = Math.sqrt(a);

console.log(squareRoot);  // Output: 5

8. Using Parentheses for Order of Operations

let a = 2;
let b = 3;
let c = 4;
let result = (a + b) * c;

console.log(result);  // Output: 20

9. Increment and Decrement

let a = 5;
a++;  // Increment by 1

console.log(a);  // Output: 6

let b = 10;
b--;  // Decrement by 1

console.log(b);  // Output: 9

10. Handling Floating Point Numbers

let a = 0.1;
let b = 0.2;
let sum = a + b;

console.log(sum);  // Output: 0.30000000000000004 (floating-point precision issue)

let roundedSum = sum.toFixed(2);  // Round to 2 decimal places

console.log(roundedSum);  // Output: 0.30


JS

JavaScript, the concept of "left-to-right" often called left-to-right evaluation or left-to-right associativity

Javascript 
let result = 5 + 3 * 2;
console.log(result); // Output: 11

Example 1 Basic Arithmetic

Javascript 

let result = 5 + 3 * 2; console.log(result); // Output: 11

Here’s the breakdown:

• The * (multiplication) operator has higher precedence than + (addition), so JavaScript will evaluate 3 * 2 first, resulting in 6.
• Then, it evaluates 5 + 6, which results in 11.

Even though the expression goes left-to-right for addition and multiplication, operator precedence affects the order in which operations occur.

Example 2: Assignment with Multiple Operations

javascript 
let x = 2;
let y = 3;
let result = x + y * 4 - 1;
console.log(result); // Output: 13

1. First, y * 4 is evaluated (left-to-right) because multiplication has higher precedence than addition and subtraction, giving 12.
2. Then, x + 12 is calculated (left-to-right), which is 2 + 12 = 14.
3. Finally, 14 - 1 is calculated, resulting in 13.

Example 3: Logical Operators

JavaScript also evaluates logical operators left to right:

javascript 
let a = true;
let b = false;
let result = a && b || true;
console.log(result); // Output: true

• First, a && b is evaluated (left-to-right), which results in false because b is false.
• Then, false || true is evaluated, which results in true.

Example 4: Chaining Assignments

javascript
let x = 5;
let y = x = 10;
console.log(x); // Output: 10
console.log(y); // Output: 10

Here, the assignment is evaluated left-to-right:

1. x = 10 is executed first, so x becomes 10.
2. Then, y = 10 is executed, so y also gets the value 10.