Typescript
typescript is a typed superset of javascript
developed by microsoft
object oriented
suport ecma script
we can use data types,classes,interface etc
ide support..code hinting availabale
function overriding problem solve..
node js npm
....promise async await....
npm install -g typescript..to install in window....
error:----
duplicate identifier A
cannot redeclaare block-scoped variable ob..
export{}
what is watch:----
watch for the file changes and recompile them..
datatypes:---
Array:---down check....
object
union:--1 se jyada type
...class inside function no need of let and func
interface:--
data type define function/object/class property ...
template create...
if there will be change auto convert..
tsc app.ts--watch
run file without browser
let conversion:----
bz of diff browser let doesnt support that's why we use...
type declaration:----
let a:string
Array:---
export { }
//let A = Array(1, 2, 3, 4);
let A: number[] = [1, 2, 3, 4, "gaurav"];
//auto type define string and int bz both value are present
console.log(typeof (A));
//A.push();
A[2] = true;
console.log(A[2])//now only number..
object:---------
....default type object...
update property
add new property
define a custom type for object
use any with object...any data willbe accepted
union type:----
let data:string|number....multiple type allow
let data=.........any data value
export { }
interface usertype {
name: string,
age: number,
address: number,
getdata: () => string,
}
let user: usertype = {
name: 'peter',
age: 30,
address: 20,
getdata: function () {
return "hi";
}
}
//function cals():number...only no will return
function A(a: number, b?: number): number {
return b ? a + b : a;
}
console.log(A(20, 30));
//class:---
no need to define variable by using let/var
constructor()...syntax...
:void doesnt return anything...
//parent:...extends inheritance...
module:------
teacher/student..
export default st{
}
import slogin from './student'
object...
access property..
1....export { }
let A: number[] = [1, 2, 3, 4];
A.push()
html+js+ts:---error....
first.js:2 Uncaught ReferenceError: exports is not defined
at first.js:2
<script> var exports = {};</script>
function:----
export { }
function f1(a: number, b?: number) {
return b ? a + b : a;
}
console.log(f1(4, 5));
class:-----
export { }
class A {
name: string;
constructor(name) {
this.name = name;
}
getdata() {
return this.name;
}
}
let ob = new A('gaurav');
console.log(ob.getdata())
inheritance:--
export { }
class A {
name: string;
constructor(name) {
this.name = name;
}
getdata(): string {
return this.name;
}
}
class B extends A {
constructor(name) {
super('raj');
console.log(name);
}
}
let ob = new B('gaurav');
console.log(ob.getdata())
Modules:---
block of code related function class we use to save
if same class in one file so the error will occur
bz function cant be redclare in same file...
export default func1()//samename
{
}
export default funct2()//same name
{
}
import A from './func1'
import A from './func2'
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