Reverse a Number in JavaScript

1// Method 1: Using while loop
2function reverseNumber(num) {
3    let reversed = 0;
4    let original = num;
5    
6    while (num > 0) {
7        let digit = num % 10;
8        reversed = reversed * 10 + digit;
9        num = Math.floor(num / 10);
10    }
11    
12    return reversed;
13}
14
15console.log("Reverse of 1234:", reverseNumber(1234));
16console.log("Reverse of 5678:", reverseNumber(5678));
17
18// Method 2: Using string conversion
19function reverseNumberString(num) {
20    return parseInt(num.toString().split('').reverse().join(''));
21}
22
23console.log("\nUsing string method:");
24console.log("Reverse of 1234:", reverseNumberString(1234));
25console.log("Reverse of 9876:", reverseNumberString(9876));
26
27// Method 3: Using array methods
28function reverseNumberArray(num) {
29    return parseInt(
30        num.toString()
31           .split('')
32           .reverse()
33           .join('')
34    );
35}
36
37console.log("\nUsing array methods:");
38console.log("Reverse of 5432:", reverseNumberArray(5432));
39
40// Method 4: Handling negative numbers
41function reverseNumberComplete(num) {
42    let isNegative = num < 0;
43    num = Math.abs(num);
44    
45    let reversed = 0;
46    while (num > 0) {
47        reversed = reversed * 10 + (num % 10);
48        num = Math.floor(num / 10);
49    }
50    
51    return isNegative ? -reversed : reversed;
52}
53
54console.log("\nWith negative support:");
55console.log("Reverse of -1234:", reverseNumberComplete(-1234));
56console.log("Reverse of 5678:", reverseNumberComplete(5678));