Question

I have an array

var hex_to_dec = {
    '0' : 0,
    '1' : 1,
    '2' : 2,
    '3' : 3,
    '4' : 4,
    '5' : 5,
    '6' : 6,
    '7' : 7,
    '8' : 8,
    '9' : 9,
    'A' : 10,
    'B' : 11,
    'c' : 12,
    'D' : 13,
    'E' : 14,
    'F' : 15
};

and a function

function get_dec_from_hex(key){//if key=A
    console.log(hex_to_dec["A"]);//works
    return hex_to_dec[key];//doesnt work
}

i am trying to get the value when the key is a letter and it doesnt work… but when the key is a number i can get the value without getting “undefined” output

Answer 1

You don’t have to maintain that list of conversion’s yourself, parseInt will get you there easier.

try this in your console:

parseInt('1', 16) // 1
parseInt('2', 16) // 2
...
parseInt('A', 16) // 10
parseInt('B', 16) // 11
...
parseInt('F', 16) // 15

---

From https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/parseInt

Parses a string argument and returns an integer of the specified radix
or base.

var intValue = parseInt(string[, radix]);

string

The value to parse. If string is not a string, then it is converted to
one. Leading whitespace in the string is ignored.

radix

An integer that represents the radix of the above mentioned string. While this
parameter is optional, always specify it to eliminate reader confusion
and to guarantee predictable behavior. Different implementations
produce different results when a radix is not specified.