?? - TypeScript? ??????

• TypeScript? Javascript? ?? ?????
• ?? ??? ???? ??? ?? ?? ??? ???? ??? ??? ? ????.
• ?????, ???, ??? ?? ?? ??? ?????.
• ? ?? ?? ??, ??? ?? ? ??? ?? ???? ?????.

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?? - ??? ? ??? ?? ???? ??????

• ????? ??? ???? ?? ?????. ??? ?? -

let firstName: string = "Rutvik";

• ??? ??? TypeScript? ?? ???? ??? ????? ?????. ?? ??? ??? ?????.

let age = 23;

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?? - TypeScript?? ?? ?, ? ? ?? ?, ?? ?? ?? ???? ??????

• any ??? ?? ??? ??? ???? ? ?????.
• ?? ??? ?? ???? ??? ???? ????.

let x: any = 10;
x = 'hello'; // No TypeScript error
console.log(x.toUpperCase()); // No TypeScript error

• ?? ?? ??? ???? ?? ??? ???? ?? ??? ? ? ?? ??? any ???? ????.

let y: unknown = 10;
// Type assertion needed before using y as number
if (typeof y === 'number') {
    console.log(y.toFixed(2));
}

• ?? ?? ???? ?? ?? ???? ????.
• ????? ??? ???? ?? ??? ???? ?????.

function throwError(message: string): never {
    throw new Error(message);
}

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?? - ?? ??? ??? ??????

• ??? ????? ??? ?? ??? ???? ???. ?? ??? ??? ??? ??? ??? ? ????.

const names: string[] = ["Rutvik", "Rohit", "Virat"];
names.push("Bumrah"); // no error

• ?? ??? ???? ?? ?? ???? ??? ?? ????.

const names: readonly string[] = ["Rutvik", "Rohit", "Virat"];
names.push("Bumrah"); // Error: Property 'push' does not exist on type 'readonly string[]'.

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?? - ??? ?? ???? ??????

• ??? ??? ???? ??? ???? ??? ?????.

const numbers = [1, 2, 3]; // inferred to type number[]
numbers.push(4); // no error

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?? - ??? ??????

• ??? ??? ?? ??? ?? ?????.
• ?? ??? ?? ?? ??? ???? ? ?? ?????.

let ourTuple: [number, boolean, string];

// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];

---

?? - ?? ?? ??? ??????

• ??? ?? ???? ??? ??? ??? ??? ? ?? ??? ??? ? ??? TypeScript? ??? ????? ????.

let ourTuple: [number, boolean, string];

// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];
//No safety in indexes from 3
ourTuple.push('This is wrong');

• ?? ? ??? ???? ?? ?? ?? readonly ???? ?????.

let ourTuple: readonly [number, boolean, string];
// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];
// throws error as it is readonly
ourTuple.push('Coding Hero took a day off');

---

?? - ?? ??? ??? ??????

• ???? ?? ?? ??? ???? ??? ?? ? ??? ???? ?? ??? ??? ? ????.

interface CarTypes {
    brand: string,
    model: string,
    year: number
}


const car: CarTypes = {
  brand: "Tata",
  model: "Punch",
  year: 2020
};

---

?? - ??? ??? ??? ?? ??? ??????

• ??? ???? ?? ????? ? ? ? ??.

let firstName: string = "Rutvik";

---

?? - TypeScript? ???? ?????????

• ???? ??? ?? ?????. ? ?? ?? ?? ???? ???.
• ?? ????? ???? 0?? ???? 1? ?????.
• ?? ?? ??? ??? ? ????.

let age = 23;

let x: any = 10;
x = 'hello'; // No TypeScript error
console.log(x.toUpperCase()); // No TypeScript error

---

?? - ?? ???? ??????

• ??? ?? ???? ??? ??? ? ??? ??? ? ??? ?? ?? ?? ??? ?? ?? ? ??? ?? ?? ???? ??? ? ????.

let y: unknown = 10;
// Type assertion needed before using y as number
if (typeof y === 'number') {
    console.log(y.toFixed(2));
}

---

?? - ?????? ??????

• ?????? ??? ????? ???? ??? ? ????.

function throwError(message: string): never {
    throw new Error(message);
}

---

?? - ?????? ???? ??? ??????

• extend ???? ???? ?????? ??? ? ????.

const names: string[] = ["Rutvik", "Rohit", "Virat"];
names.push("Bumrah"); // no error

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?? - Union ? Intersection ??? ??????

?? :-

• Union ??? ??? ????? ??? ?? ? ??? ?? ? ?? ??? ?????.
• ??? ??? OR???? ?? | ??.

const names: readonly string[] = ["Rutvik", "Rohit", "Virat"];
names.push("Bumrah"); // Error: Property 'push' does not exist on type 'readonly string[]'.

??? :-

• ???? ?? ??? ??? ??? ? ?????.
• ?? ??? AND??? ?? & ??? ???? ?????.

const numbers = [1, 2, 3]; // inferred to type number[]
numbers.push(4); // no error

---

?? - Typescript? ??? ??????

???? ?? ??? ???? ??? ??????

• ?? ?? ?? : ??? ???? ??? ?? ??? ??? ? ????.

let ourTuple: [number, boolean, string];

// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];

??? ???? ??? ???? ??? ??????

• ? ???? ?? : ??? ???? ???? ??? ???? ?????? ??? ??? ? ????.

let ourTuple: [number, boolean, string];

// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];
//No safety in indexes from 3
ourTuple.push('This is wrong');

??? ???, ?? ? ??? ????? ???? ??? ??????

• ?? ????? ???? ????? ?????? ??? ? ????. ??? c? ?????? ?? ?????.

let ourTuple: readonly [number, boolean, string];
// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];
// throws error as it is readonly
ourTuple.push('Coding Hero took a day off');

• ???(ES6 ??)? ?? ?? ???.

interface CarTypes {
    brand: string,
    model: string,
    year: number
}


const car: CarTypes = {
  brand: "Tata",
  model: "Punch",
  year: 2020
};

• ??? ????(ES6 ??)? ??? ??? ??? ????? ?? ??? ?????.

interface CarTypes {
    brand: string,
    model: string,
    year?: number
}

const car: CarTypes = {
  brand: "Tata",
  model: "Punch"
};

---

?? - TypeScript?? ????? ??????

• ???? ?? ??? ????? ???????.
• ?? ???? ??? ? ? ??? as ???? ?? ???? ???? ???.

enum Direction {
  Up = 1,
  Down,
  Left,
  Right,
}
console.log(Direction.Up); // 1
console.log(Direction.Down); // 2

• <> as ???. ? ? ?? ?????.

let firstName: string = "Rutvik";

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?? - TypeScript? ????? ??????

• Typeascript? ???? ???? ?? ??? ??? ??? ? ?? ??? ??? ?? ??? ??? ?? ? ????.

let age = 23;

---

?? - Typescript? ???? ???

• TypeScript? ???? ?? ??? ????? ?? ???? ??? ?????.
• ??? ??? ???? ?? ? ????? ??? ? ?? ???? ?? ??? ? ????.
• ??? ????? ???? ???? ??? ?? ?????.

1. ???

• T ??? ?? ??? ????? ????.
• ?? ??: ?? ??? ??? ??? ????? ??.

let x: any = 10;
x = 'hello'; // No TypeScript error
console.log(x.toUpperCase()); // No TypeScript error

2. ??

• T ??? ?? ??? ??? ????.
• ?? ??: ?? ??? ???? ?? ????? ??.

let y: unknown = 10;
// Type assertion needed before using y as number
if (typeof y === 'number') {
    console.log(y.toFixed(2));
}

3. ?? ??

• T ??? ?? ??? ?? ???? ????.
• ?? ??: ??? ??? ??? ? ??? ???.

function throwError(message: string): never {
    throw new Error(message);
}

4. ??

• ?? T?? ?? K ??? ???? ??? ?????.
• ?? ??: ??? ?? ??? ??? ??.

const names: string[] = ["Rutvik", "Rohit", "Virat"];
names.push("Bumrah"); // no error

5. ??

• ?? T?? ?? K ??? ???? ??? ?????.
• ?? ??: ?? ??? ??? ?? ??? ?? ?.

const names: readonly string[] = ["Rutvik", "Rohit", "Virat"];
names.push("Bumrah"); // Error: Property 'push' does not exist on type 'readonly string[]'.

6. ??

• ? K? T ??? ?? ???? ??? ?????.
• ?? ??: ?? ?? ??? ? ??? ???? ?? ??? ?????.

const numbers = [1, 2, 3]; // inferred to type number[]
numbers.push(4); // no error

7. ??

• U? ??? ? ?? ?? ??? T ???? ?????.
• ?? ??: ?? ??? ??????.

let ourTuple: [number, boolean, string];

// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];

8. ??

• U? ??? ? ?? T ????? ?????.
• ?? ??: ??? ?? ?? ???? ???? ??.

let ourTuple: [number, boolean, string];

// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];
//No safety in indexes from 3
ourTuple.push('This is wrong');

9. Null? ???? ??

• T ???? null ? ???? ??? ?????.
• ?? ??: ?? null? ??? ????? ??? ?????.

let ourTuple: readonly [number, boolean, string];
// initialize correctly
ourTuple = [5, false, 'Coding Hero was here'];
// throws error as it is readonly
ourTuple.push('Coding Hero took a day off');

10. ?? ??

• ?? ??? ?? ??? ?????.
• ?? ??: ??? ?? ??? ???? ?????.

interface CarTypes {
    brand: string,
    model: string,
    year: number
}


const car: CarTypes = {
  brand: "Tata",
  model: "Punch",
  year: 2020
};

11. ???? ??

• ??? ?? ?? T? ???? ???? ??? ??? ?????.
• ?? ??: ??? ????? ??? ?????.

interface CarTypes {
    brand: string,
    model: string,
    year?: number
}

const car: CarTypes = {
  brand: "Tata",
  model: "Punch"
};

12. ????

• ?? ??? ???? ??? ?????.
• ?? ??: ??? ???? ??? ??????.

enum Direction {
  Up = 1,
  Down,
  Left,
  Right,
}
console.log(Direction.Up); // 1
console.log(Direction.Down); // 2

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? ??? TypeScript ??? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!