이상한 자바스크립트의 단점과 특징 😵

안녕! 모든 사람!! 이 기사에서는 이상한 JavaScript의 이상하고 환상적인 특징과 특성에 대해 설명합니다. JavaScript는 매우 특이한 프로그래밍 언어입니다. 다른 프로그래밍 언어와 다르지만 강력한 언어입니다. 프런트 엔드, 백엔드, 모바일 및 데스크톱 앱을 구축하는 데 사용할 수 있습니다. JavaScript의 기초에 대해 자세히 알아보려면 이전 기사를 방문하십시오. =>

그래서 더 이상 고민하지 않고 바로 그 기묘함으로 뛰어 들어 갑시다.

!10 + !10

!10 + !10 ---> 0 

The positive numbers in javascript are always true.

This Logical Not (!) represents the opposite. So, the opposite of true is false.

Hence, the false gets converted to 0.

So the answer is 0.

[] + []

[] + [] ---> ""

When using the addition operator, both the left and right operands are converted to primitives.

Converting an array to a primitive return its default value, which for objects with a valid toString() method is the result of calling object.toString()

For arrays this is the same as calling array.join()

Joining empty array results in an empty string.

Hence, the addition operator returns the concatenation of two empty strings, which is the empty string.

더 자세한 설명은 => Dr. Axel Rauschmayer의 이 문서를 참조하세요.

[2,4,6,8,10] + [12,14,16,18] = "2,4,6,8,1012,14,16,18"

[2,4,6,8,10] + [12,14,16,18] ---> "2,4,6,8,1012,14,16,18"

Arrays are converted into strings and then they are concatenated.

It follows the same rule as above.

난 === 난

NaN === NaN ---> false

Because it was the decision made by the IEEE-754 committee.

function isNaN didint exsist at that time.

자세한 설명은 => Stephen Canon의 StackOverflow 답변을 참조하세요.

NaN++

NaN++ ---> NaN

NaN literally means Not A Number.

Hence, NaN cannot be incremented.

정의되지 않은 + 참 | 정의되지 않음 + 거짓

undefined + true ---> NaN

undefined + false ---> NaN

True and False can be converted to numbers.

undefined cannot be converted to a number.

However , !!undefined + false => 0 , because (!!undefined means false).

!!undefined === false is true

Hence, If undefined is added with any boolean the result will always be NaN.

+0 === -0

+0 === -0 ---> true

Positive Zero and Negative Zeros are always equal in JavsScript.

[,,,].길이

[,,,].length ---> 3

This [,,,] simply means the array containing three empty slots.

The last comma is a trailing comma.

참 + 거짓

true + false ---> 1

Both the booleans are converted into their respective numerical representation and their values are added.

Number(true) ---> 1

Number(false) ---> 0

1 + 0 ---> 1

0.2 + 0.1 === 0.3

0.2 + 0.1 === 0.3 ---> false

Just think about representing 1/3 as a decimal value. It's impossible to do exactly! In the same way, 1/10 (decimal 0.1) cannot be represented exactly in binary as a "decimal" value; a repeating pattern after the decimal goes on forever and ever. The value is not exact, and therefore you can't do exact math with it using normal floating-point methods.

2,4 | 1,2,3,4,5 | "특이점", "특징"

2,4 ---> 4
1,2,3,4,5 ---> 5
"quirks","features" ---> "features"

The comma operator (,) evaluates each of its operands (from left to right) and returns the value of the last operand.

!!""

!!"" ---> false

Boolean representation of empty string("") is false.

Boolean("") ---> false

So, !!false ---> false

Inside Logical Not Operator(!) anything with a value is true and anything without a value is false.

+!![]

+!![] ---> 1

Boolean representation of empty array [] is true.

!!true is always true.

Plus operator converts into a numerical representation of that particular Boolean value.

Hence, +true is 1 .

참 == "참" ---> 거짓

true == "true" ---> false

Both of these values are converted to numbers .

Number(true) ---> 1

Number("true") ---> NaN

Hence, 1 == NaN is false

020 - 05

020 - 05 ---> 11

020 is treated as an octal number in JavaScript.

Its value in decimal is 16.

Hence, 16 - 5 is 11

"" - - ""

"" - - "" ---> 0

Empty string is converted into 0

It literally means (+0) - (-0)

Hence, (+0) - (-0) is zero.

널 + 420

null + 420 ---> 420

Numerical representation of null is always 0.

Number(null) ---> 0

Hence, 0 + 420 is 420

(널 - 0) + "0"

(null - 0) + "0" ---> "00"

Number(null) is 0

so, 0 - 0 is 0.

0 + "0" concatenates it and gives "00" as an answer.

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