Question

How to reverse an integer number in JavaScript

Answer 1

function reverseNumber(num) {
	let is_positive = 1;
           
    if (num < 0) {
        is_positive = -1;
        num = num * -1;
    }
           
    let reverse = 0;
    while (num > 0) {
        let remainder = num % 10;
        reverse = reverse * 10 + remainder;
        num = Math.floor(num / 10);
    }
           
    if (is_positive == -1) {
        reverse = reverse * -1;
    }
    
    return reverse;
}

console.log(reverseNumber(12345))

console.log(reverseNumber(-904))



/*
run:
  
54321
-409
           
*/

 

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Answer 2

function reverseNumber(num) {
	return (
        parseFloat(num
                    .toString()
                    .split('')
                    .reverse()
                    .join('')
        ) * Math.sign(num)
    )
}

console.log(reverseNumber(12345))

console.log(reverseNumber(3.14))

console.log(reverseNumber(-983))

console.log(reverseNumber(-8.203))

console.log(reverseNumber(1900000))
 



/*
run:
  
54321
41.3
-389
-302.8
91
           
*/

 

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Answer 3

function reverseNumber(num) {
	let str = num.toString();
	
	let arr = str.split('');
	arr.reverse();
	str = arr.join('');
	
	num = parseFloat(str);

    return num;
}

console.log(reverseNumber(12345))



/*
run:
  
54321
           
*/

 

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