[Javascript ] 자바스크립트 랜덤 숫자, Math Random() 함수

JavaScript 

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• JavaScript는 웨페이지에서 복잡한 기능을 구현할 수 있도록 하는 객제현 스크린팅 프로그램밍 언어입니다.
• 자바스크립트는 동적이며, 타입을 명시할 필요가 없는 인터프리터 언어입니다.
• 자바스크립트는 객체 지향형 프로그래밍과 함수형 프로그래밍을 모두 표현할 수 있습니다.
• Interpreted Language as JavaScript, Python Ruby
• Compiled Languages: Java, C/C++, Swift

 

 

Math Random() 함수

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• Static method returns a floating-point, random number between 0 and 1.
• Getting a random number between two numbers

 function getRandomNumbers(startPoint, endPoint) {
        return Math.random() * (endPoint - startPoint) + startPoint; 
     }

getRandomNumbers(5,200);

 

• Getting a random integer between two values

function getRandomInteger(startPoint, endPoint) {
       
    startPoint = Math.ceil(startPoint); 
    endPoint = Math.ceil(endPoint);
    return Math.random() * (endPoint - startPoint) + startPoint; 
}

 getRandomInteger(5,200)

 

• Math.Random() + Math.floor() => only integer random numbers

function getRandomInteger(startPoint, endPoint) {
       
    startPoint = Math.ceil(startPoint); 
    endPoint = Math.ceil(endPoint);
    
    return Math.floor(Math.random() * (endPoint - startPoint) + startPoint); 
}

 getRandomInteger(5,200)

 

 

 

Comparators and Equality,  Strict equality 

재미있는 조건문 연산자 맛보기

• Equality " == " : operator checks whether its two operands are equal, returning a Boolean value.
• Object: return " true " only if its two operands are same abject
• String: return " true " only if two operands have same characters with same order
• Boolean : return " true " only if two operands both true or false
• BigInt: return true only if both operands have the same value
• Symbol: return true only if both operands reference the same symbol
• If one of operands is null or undefined, other must be null or undefined for returned true
• Super Interesting Samples  : 

1 == 1,  true
'hello' == 'hello',  true
'1' == 1, true
0 == false,  true
+0 == -0 , true
Nan == Nan, is false
null == null, true
null == undefined, true
undefined == undefined, true

 

• Strict Equality " === " : operator checks whether the two operands are equal, returning a Boolean value.
• Difference of equality between Strict Equality.  Most notable difference of equality vs strict equality is that if the operands are different types the == operator attempts to convert them to the same type before comparing.
       
• Unlike the equality "==", the strict equality operator always consider operands of different types to be different.
• Equality vs Strict Equality Samples:

+0 === -0, returns true

1 == 1 vs 1 === 1 
//also returns true

'hello' == 'hello' 'hello' === 'hello'
// both true

'1' == 1 is true, but '1' === 1 returns false

0 == false is true,  but '0' === 'false' is exactly false

 

• if both operations are null or undefined, returns true

null == undefined is true,  but null === undefined is false

 

• If either operands is NaN, returns false.

NaN == NaN, NaN === Nan, returns false

 

 

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