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"
    if(num<0)
        num += Math.pow(2,32)
    ans = ""
    arr = ["0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"]
    while(num){
        ans = arr[num%16] + ans
        num = parseInt(num/16)
    }
    return ans
};