console-1628318003707.log

var a;// variable declare
undefined
typeof a;
"undefined"
a;
undefined
a=100;
100
typeof a;
"number"
a=1;
1
typeof a;
"number"
a=454545654654654;
454545654654654
typeof a;
"number"
a=90.20;
90.2
typeof a;
"number"
a=545.3232323232323
545.3232323232323
typeof a;
"number"
a=100/0;
Infinity
typeof a;
"number"
a=100;
100
var b = "Amit";
undefined
typeof a;
"number"
typeof b;
"string"
a + b
"100Amit"
var c = a - b;
undefined
c;
NaN
typeof c;
"number"
'Ur Balance is '+c;
"Ur Balance is NaN"
isNaN(c);
true
c;
NaN
isNaN(c)?0:c;
0
'Ur Balance is '+(isNaN(c)?0:c);
"Ur Balance is 0"
var c= 100/0;
undefined
c;
Infinity
isFinite(c)
false
isFinite(c)?c:0
0
var a = 100;
undefined
var b = "200";
undefined
a + b;
"100200"
a + parseInt(b);
300
b = "200.90";
"200.90"
a + parseFloat(b);
300.9
window;
Window {window: Window, self: Window, document: document, name: "", location: Location, …}
typeof window;
"object"
window instanceof Window;
true
typeof Window;
"function"
window.isNaN(c);
false
window.parseInt("9999");
9999
window.open('https://www.brain-mentors.com');
Window {window: Window, self: Window, document: document, name: "", location: Location, …}
var x = "Amit";
undefined
typeof x;
"string"
x = 'Amit';
"Amit"
typeof x;
"string"
x= 'A';
"A"
typeof x;
"string"
x= `gjdhgfdjkghfjkhgjkfdghkjdfhgkfhgkhfjdkj
ghfdkjgjkfdhgkjhfdghkdf
ghdfkjhgjkfdhgkjhfdjk
ghdfkjgh`;
"gjdhgfdjkghfjkhgjkfdghkjdfhgkfhgkhfjdkj\nghfdkjgjkfdhgkjhfdghkdf\nghdfkjhgjkfdhgkjhfdjk\nghdfkjgh"
typeof x;
"string"
x;
"gjdhgfdjkghfjkhgjkfdghkjdfhgkfhgkhfjdkj\nghfdkjgjkfdhgkjhfdghkdf\nghdfkjhgjkfdhgkjhfdjk\nghdfkjgh"
a = 100;
100
b = 200;
200
c = a + b;
300
"A is "+a+" B is "+b+" c is "+c;
"A is 100 B is 200 c is 300"
`A is ${a} B is ${b} c is ${c}`;
"A is 100 B is 200 c is 300"
var c = true;
undefined
typeof c;
"boolean"
c = false;
false
typeof c;
"boolean"
true + true;
2
true - false
1
100 + true;
101
100 + "100"
"100100"
100 - "100"
0
100 * "10"
1000
100 / "10"
10
var a = Number.MAX_SAFE_INTEGER;
undefined
a;
9007199254740991
++a;
9007199254740992
++a;
9007199254740992
++a;
9007199254740992
++a;
9007199254740992
++a;
9007199254740992
var r = 9007199254740992 + 534423432423423
undefined
typeof r;
"number"
r;
9541622687164416
a= Number.MAX_SAFE_INTEGER;
9007199254740991
++a;
9007199254740992
++a;
9007199254740992
a= 9007199254740992n;
9007199254740992n
typeof a;
"bigint"
a + 8654654435534534553n
8663661634789275545n
c = a + 8654654435534534553n
8663661634789275545n
typeof c;
"bigint"
c;
8663661634789275545n
var f = BigInt("53453453534534535432534534");
undefined
typeof f;
"bigint"
f;
53453453534534535432534534n
100n + 100;
VM2710:1 Uncaught TypeError: Cannot mix BigInt and other types, use explicit conversions
    at <anonymous>:1:6
(anonymous) @ VM2710:1
100n + 100n
200n
var arr = [10,20,30,40];
undefined
typeof arr;
"object"
arr instanceof Array;
true
typeof Array;
"function"
arr[0];
10
arr[1];
20
arr.length;
4
arr.push(99999);
5
arr;
(5) [10, 20, 30, 40, 99999]
arr.pop();
99999
arr;
(4) [10, 20, 30, 40]
arr = null;
null
typeof arr;
"object"
arr.length;
VM3165:1 Uncaught TypeError: Cannot read property 'length' of null
    at <anonymous>:1:5
(anonymous) @ VM3165:1
var t1 ;
undefined
typeof t1;
"undefined"
var t2 = null;
undefined
typeof t2;
"object"
1000 + t1;
NaN
1000 + undefined
NaN
1000 + null
1000
undefined == null
true
undefined === null;
false
var price = 10000;
undefined
price;
10000
var price = 10000.20;
undefined
price;
10000.2
price.toLocaleString('hi-IN');
"10,000.2"
price.toLocaleString('fr-FR');
"10 000,2"
price;
10000.2
var formattedPrice = price.toLocaleString('fr-FR');
undefined
formattedPrice
"10 000,2"
price;
10000.2
var name = "Amit";
undefined
name.toUpperCase();
"AMIT"
name;
"Amit"
var t = name.toUpperCase();
undefined
t;
"AMIT"
name;
"Amit"
var emp = {id:1001, name:'Amit'};
undefined
typeof emp;
"object"
emp instanceof Object;
true
typeof Object;
"function"
var arr = [10,20];
undefined
typeof arr;
"object"
arr instanceof Array;
true
arr instanceof Object;
true
emp;
{id: 1001, name: "Amit"}
emp.id;
1001
emp.name;
"Amit"
var f = emp;
undefined
f;
{id: 1001, name: "Amit"}
f === emp;
true
f.id = 100000;
100000
emp;
{id: 100000, name: "Amit"}
var arr= [10,90,20,30,40,50];
undefined
arr.sort();
(6) [10, 20, 30, 40, 50, 90]
arr;
(6) [10, 20, 30, 40, 50, 90]
var arr= [10,90,20,30,40,50];
undefined
var vv = [...arr];
undefined
vv;
(6) [10, 90, 20, 30, 40, 50]
arr;
(6) [10, 90, 20, 30, 40, 50]
vv === arr;
false
vv[0] =324343;
324343
vv;
(6) [324343, 90, 20, 30, 40, 50]
arr;
(6) [10, 90, 20, 30, 40, 50]
emp;
{id: 100000, name: "Amit"}
var y = {...emp};
undefined
y;
{id: 100000, name: "Amit"}
y === emp;
false
y.id = 7777;
7777
emp;
{id: 100000, name: "Amit"}
y;
{id: 7777, name: "Amit"}
var t = 1000;
undefined
typeof t;
"number"
t.toString();
"1000"
var n = "Amit";
undefined
typeof n;
"string"
n.toUpperCase();
"AMIT"
n.toLowerCase();
"amit"
n.charAt(0);
"A"
var e = 1000;
undefined
typeof e;
"number"
var e= new Number(1000);
undefined
typeof e;
"object"
typeof Number;
"function"
var g = 1000;
undefined
typeof g;
"number"
var f = new String("Hello");
undefined
typeof String;
"function"
typeof f;
"object"
var bb = "Hello";

undefined
typeof bb;
"string"
f;
String {"Hello"}0: "H"1: "e"2: "l"3: "l"4: "o"length: 5__proto__: Stringanchor: ƒ anchor()big: ƒ big()blink: ƒ blink()bold: ƒ bold()charAt: ƒ charAt()charCodeAt: ƒ charCodeAt()codePointAt: ƒ codePointAt()concat: ƒ concat()constructor: ƒ String()endsWith: ƒ endsWith()fixed: ƒ fixed()fontcolor: ƒ fontcolor()fontsize: ƒ fontsize()includes: ƒ includes()indexOf: ƒ indexOf()italics: ƒ italics()lastIndexOf: ƒ lastIndexOf()length: 0link: ƒ link()localeCompare: ƒ localeCompare()match: ƒ match()matchAll: ƒ matchAll()normalize: ƒ normalize()padEnd: ƒ padEnd()padStart: ƒ padStart()repeat: ƒ repeat()replace: ƒ replace()replaceAll: ƒ replaceAll()search: ƒ search()slice: ƒ slice()small: ƒ small()split: ƒ split()startsWith: ƒ startsWith()strike: ƒ strike()sub: ƒ sub()substr: ƒ substr()substring: ƒ substring()sup: ƒ sup()toLocaleLowerCase: ƒ toLocaleLowerCase()toLocaleUpperCase: ƒ toLocaleUpperCase()toLowerCase: ƒ toLowerCase()toString: ƒ toString()toUpperCase: ƒ toUpperCase()trim: ƒ trim()trimEnd: ƒ trimEnd()trimLeft: ƒ trimStart()trimRight: ƒ trimEnd()trimStart: ƒ trimStart()valueOf: ƒ valueOf()Symbol(Symbol.iterator): ƒ [Symbol.iterator]()__proto__: Object[[PrimitiveValue]]: ""[[PrimitiveValue]]: "Hello"
bb;
"Hello"