JavaScript Tracy Topic
JavaScript some tricky topics those you must be known. this article I want to share with you this
The first one truthy and flashy value truthy that means true and flashy which means false every developer calls this truthy and flashy. we are more knowledgeable about this some example
Truthy value
- while the number is truthy without 0 for example
var num = 12;
output= truthy; and
var num = 0;
output = flashy;
2. while the string is truthy without an empty string for example
const name = ‘kawcher ahbib’; output = truthy
const name = ‘’ output = flashy
//truthy value
- 12 -12 or ‘0’ ‘hello’ or ‘ ’
//flashy value
- 0, ‘’, undefined, null, NaN
Null vs Undefined Which One Is The Best For Find Your Girlfriend
In this article, I discuss null and undefined
Undefine
most of the case you get undefine from you mistakes example
you use var key without value
var name ; output = undefine
function num( num1, num2) {
console.log( num1 + num2)
}
num(20, 10) output = undefine
why????
because you don’t use the return key
but if you use the return key without value then it gives you undefine
Null
If you use this key then you get null for example
const num = null; you get output = null;
Check Your Orginal Girlfriend Using equal
as a web developer, you know that double equal triple equal
== double equal use for check just value
example var num1 = 12;
var num2 = ‘12’
if( num1 == num2){
console.log(“12”)
} else{
console.log(‘this is not 12’)
}
output = 12
but if you use === triple equal it’s checking your value and type
example
let num1 = 12;
let num2 = ‘12’;
if(num1 === num2){
console.log(‘it is right’)
}else{
console.log(‘it is not right)
}
output = it is not right
because of this var key value, we use two type number and string
JavaScript Scope
Scope that means your area which area you go and don’t go
for example
function yourNumber( num1, num2){
const result = num1 + num2
console.log(result)
}
yourNumber(12,20) this way you get input right value but
if you want to access outside of function then you don’t get output
example: function yourNumber( num1, num2){
const result = num1 + num2
}
console.log(result) output = undefine
yourNumber (12,20)
bind call and apply why use and how use?
bind we use this key object and another object to bind
example
var object1 = {
name = ‘kawcher’;
number = 00234049495
}
var object2 = {
name = ‘habib’
number = 8945849584
}
console.log(object1.baind(object2))
call using
console.log(object1.call(object2, joshime, 344545))
apply
console.log(object1.apply(object2, [korim, 2005458]))
window, global secop
window is a browser enverment
globle secop it’s use or access globale
