DEV Community: pouya alamdari

add new property to exist object

pouya alamdari — Sun, 02 Jan 2022 08:53:57 +0000

const person = {
    firstName: 'John',
    lastName: 'Doe',
    age: 21,
};

person.eyecolor = 'green';
console.log(person);

for ... in ... with object

pouya alamdari — Sat, 01 Jan 2022 12:44:57 +0000

const person = {
    firstName: 'John',
    lastName: 'Doe',
    age: 21,
};

let text = "";
for (let x in person) {
    text += person[x] + " ";
    console.log(text);
}

console.log(text);

object is mutable!

pouya alamdari — Sat, 01 Jan 2022 12:19:40 +0000

const person = {
    age: 30,
    firstName: 'John',
    lastName: 'Doe',
};

const x = person;

x.age = 65;
x.firstName = 'Adam';
x.lastName = 'Karpov';

console.log(x.age);
console.log(x.firstName);
console.log(x.lastName);

show java script result in Browser and Object primitive example

pouya alamdari — Sat, 01 Jan 2022 11:40:07 +0000

break continue

pouya alamdari — Wed, 29 Dec 2021 15:47:01 +0000

if use break

continue

for of

pouya alamdari — Wed, 29 Dec 2021 15:30:42 +0000

for (variable of iterable) {
  statement
}

Comparison

const colors = ['red', 'green', 'blue'];
// for in loop 
for (let x in colors) { //x or color or index or anything else!
    console.log(x);
}

const colors = ['red', 'green', 'blue'];
// for of loop
for (let x of colors){ 
    console.log(x);
}

so we use `for in` in the object

use `for of` in the array

for in

pouya alamdari — Wed, 29 Dec 2021 15:22:03 +0000

for (variable in object) {
  statement
}

while

pouya alamdari — Wed, 29 Dec 2021 13:05:22 +0000

for

pouya alamdari — Wed, 29 Dec 2021 12:36:17 +0000

for(initial expression, condition, increment expression)
(مقدار دهی اولیه ، شرط ، مقدار افزایشی)

switch case

pouya alamdari — Wed, 29 Dec 2021 12:20:54 +0000

if else

pouya alamdari — Wed, 29 Dec 2021 12:13:02 +0000


let hour = 10;

if (hour >=6 && hour <12){
    console.log("Good Morning!")
}

else if (hour >=12 && hour <18){
    console.log("Good Afternoon!")
}

else {
    console.log("Good Night! or Good evening!")
}

result:
Good Morning!

operators

pouya alamdari — Tue, 28 Dec 2021 12:17:13 +0000

ternary operators
example condition

logical operators :
AND && both of them should be _True_!

OR || if one of them be true the output be true!

NOT !

AND &&

const a = 10;
const b = -30;

console.log(a > 0 && b > 0); //true && false -> false

console.log(a > 0 && b < 0); //true && true -> true

OR ||

const a = 10;
const b = -30;

console.log(a > 0 || b > 0); //true && false -> true

console.log(a < 0 || b < 0); //false && true -> true

console.log(a < 0 || b > 0); //false && false -> false