Typescript with react & nextjs
To run .ts file use this commands
This will run .ts file directly in terminal
node filename.tsThis will create .js file from .ts file then we need index.html to run this file
tsc filename.tsData types in typescript / Javascripts
var myName = "kundalik";Here.. var - variable myName - variable Name "kudalik" - data
Now in typescript this is
let myName: string = "kundalik";Javascript topics
- Variables
- Datatypes
- String and its methods
- Number & methods
- Boolean & methods
- Object
- Array
- Functions
- Closures
- Promises and async/await
- Callbacks
- Event loop
- DOM manipulation
- ES6+ features (e.g., arrow functions, destructuring, spread/rest operators)
- Modules and imports/exports
- Error handling (try/catch)
- Prototypes and inheritance
- Classes
- JSON and APIs
- Event handling
- Regular expressions
- LocalStorage and SessionStorage
- Web APIs (e.g., Fetch API, Geolocation API)
- Debugging and performance optimization
Very important topics that must to understand in javascript
- Scope (block, function, and global)
- Hoisting
- Closures
- The "this" keyword
- Event delegation
- Asynchronous JavaScript (callbacks, promises, async/await)
- Prototype chain
- The event loop and concurrency model
- ES6+ features (e.g., destructuring, template literals, default parameters)
- Modules and tree-shaking
- Error handling and debugging
- Memory management and garbage collection
- Functional programming concepts (e.g., map, filter, reduce)
- Immutable data structures
- Performance optimization techniques
String methods
#### Commonly Used String Methods
1. **`length`** - Returns the length of the string.
```js
let str = "hello";
console.log(str.length); // 5
```
2. **`toUpperCase()`** - Converts the string to uppercase.
```js
let str = "hello";
console.log(str.toUpperCase()); // "HELLO"
```
3. **`toLowerCase()`** - Converts the string to lowercase.
```js
let str = "HELLO";
console.log(str.toLowerCase()); // "hello"
```
4. **`trim()`** - Removes whitespace from both ends of the string.
```js
let str = " hello ";
console.log(str.trim()); // "hello"
```
5. **`includes()`** - Checks if the string contains a specified substring.
```js
let str = "hello world";
console.log(str.includes("world")); // true
```
6. **`startsWith()`** - Checks if the string starts with a specified substring.
```js
let str = "hello world";
console.log(str.startsWith("hello")); // true
```
7. **`endsWith()`** - Checks if the string ends with a specified substring.
```js
let str = "hello world";
console.log(str.endsWith("world")); // true
```
8. **`slice()`** - Extracts a section of the string and returns it as a new string.
```js
let str = "hello world";
console.log(str.slice(0, 5)); // "hello"
```
9. **`substring()`** - Similar to `slice()`, but does not accept negative indices.
```js
let str = "hello world";
console.log(str.substring(0, 5)); // "hello"
```
10. **`replace()`** - Replaces a specified value with another value in the string.
```js
let str = "hello world";
console.log(str.replace("world", "everyone")); // "hello everyone"
```
11. **`split()`** - Splits the string into an array of substrings.
```js
let str = "hello world";
console.log(str.split(" ")); // ["hello", "world"]
```
12. **`charAt()`** - Returns the character at a specified index.
```js
let str = "hello";
console.log(str.charAt(1)); // "e"
```
13. **`indexOf()`** - Returns the index of the first occurrence of a specified value.
```js
let str = "hello world";
console.log(str.indexOf("world")); // 6
```
14. **`lastIndexOf()`** - Returns the index of the last occurrence of a specified value.
```js
let str = "hello world world";
console.log(str.lastIndexOf("world")); // 12
```
15. **`concat()`** - Joins two or more strings.
```js
let str1 = "hello";
let str2 = "world";
console.log(str1.concat(" ", str2)); // "hello world"
```
16. **`repeat()`** - Returns a new string with a specified number of copies of the original string.
```js
let str = "hello";
console.log(str.repeat(3)); // "hellohellohello"
```
17. **`padStart()`** - Pads the string with another string from the start to reach a specified length.
```js
let str = "5";
console.log(str.padStart(3, "0")); // "005"
```
18. **`padEnd()`** - Pads the string with another string from the end to reach a specified length.
```js
let str = "5";
console.log(str.padEnd(3, "0")); // "500"
```
19. **`match()`** - Matches a string against a regular expression.
```js
let str = "hello world";
console.log(str.match(/world/)); // ["world"]
```
20. **`search()`** - Searches the string for a match against a regular expression and returns the index.
```js
let str = "hello world";
console.log(str.search(/world/)); // 6
```
21. **`localeCompare()`** - Compares two strings in the current locale.
```js
let str1 = "apple";
let str2 = "banana";
console.log(str1.localeCompare(str2)); // -1
```
22. **`codePointAt()`** - Returns the Unicode code point of the character at a specified index.
```js
let str = "hello";
console.log(str.codePointAt(0)); // 104
```
23. **`normalize()`** - Returns the Unicode normalization form of the string.
```js
let str = "e\u0301";
console.log(str.normalize("NFC")); // "é"
```
24. **`toString()`** - Returns the string representation of the value.
```js
let str = new String("hello");
console.log(str.toString()); // "hello"
```