convert-a-number-to-hexadecimal.js

// Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two’s complement method is used.
//
//
// Note:
//
// All letters in hexadecimal (a-f) must be in lowercase.
// The hexadecimal string must not contain extra leading 0s. If the number is zero, it is represented by a single zero character '0'; otherwise, the first character in the hexadecimal string will not be the zero character.
// The given number is guaranteed to fit within the range of a 32-bit signed integer.
// You must not use any method provided by the library which converts/formats the number to hex directly.
//
//
//
// Example 1:
//
// Input:
// 26
//
// Output:
// "1a"
//
//
//
// Example 2:
//
// Input:
// -1
//
// Output:
// "ffffffff"


/**
 * @param {number} num
 * @return {string}
 */
var toHex = function(num) {
        if (num === 0) return '0';
        var mp = '0123456789abcdef';
        var ans = '';
        for (var i = 0; i < 8; i++) {
            n = num & 15;
            c = mp[n];
            ans = c + ans;
            num = num >> 4;
        }
        return ans.replace(/^[0]*/g, '');
};