Convert Hex to Decimal in JavaScript

In this post, we'll learn how to convert hexadecimal numbers to decimal in JavaScript.

To do this, we will write a function that takes a hexadecimal string as an argument and returns its decimal representation.

For example, we want the following input to return the following output:

JAVASCRIPT
const hex1 = "2"; // Should return 2
const hex2 = "35"; // Should return 53
const hex3 = "1f4"; // Should return 500
const hex4 = "7b2"; // Should return 1970
const hex5 = "123abc"; // Should return 1194684

parseInt()

The best way to convert a hexadecimal number to decimal is to make use of the parseInt() function.

The parseInt() function takes a string as an argument and returns an integer.

JAVASCRIPT
parseInt(string, radix);

The first argument of it is the string to be converted, and the second argument is the radix (base) of the number.

Since we are converting to a hexadecimal number, the radix is 16, since there are 16 hexadecimal digits.

With this, we can create a function called hexToDecimal that takes a hexadecimal string and returns its decimal equivalent.

JAVASCRIPT
const hexToDecimal = hex => parseInt(hex, 16);

Let's test our function:

JAVASCRIPT
const hexToDecimal = hex => parseInt(hex, 16);

const dec1 = hexToDecimal("2");
const dec2 = hexToDecimal("35");
const dec3 = hexToDecimal("1f4");
const dec4 = hexToDecimal("7b2");
const dec5 = hexToDecimal("123abc");

console.log(dec1); // 2
console.log(dec2); // 53
console.log(dec3); // 500
console.log(dec4); // 1970
console.log(dec5); // 1194684

Our function is working as intended, converting our hexadecimal numbers to decimal!

Conclusion

We've seen how you can use parseInt() in JavaScript to convert a hexadecimal number to decimal.

Hopefully, this post has been useful to you and you can use it to convert hexadecimal numbers to decimal in your own projects.

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