Convert between binary and decimal numbers in JavaScript
I don't often work with binary numbers, but whenever I do, I find myself looking up certain pieces of information over and over again. This is especially true when I need to convert a binary string to a decimal number or vice versa. Let's take a look at how to do this in JavaScript.
Binary to decimal
Given a binary string, you can use Number.parseInt() with a base of 2 to indicate the string is in binary format and convert it to its decimal equivalent.
const binaryToDecimal = binary => Number.parseInt(binary, 2);
binaryToDecimal('10'); // 2
binaryToDecimal('110'); // 6You may also use the BigInt constructor to convert a binary string to a BigInt. This is useful when dealing with very large numbers that exceed the range of regular integers.
const binaryToBigInt = binary => BigInt(`0b${binary}`);
binaryToBigInt('10'); // 2n
binaryToBigInt('110'); // 6nNotice the 0b prefix in the string passed to BigInt? This prefix indicates that the string is a binary number. In fact, you can use this in your code when writing out a numeric value in binary, like this:
const binaryNumber = 0b10; // 2 (Number)
const bigIntBinaryNumber = 0b10n; // 2n (BigInt)Decimal to binary
To convert a decimal number to a binary string, use Number.prototype.toString() with a base of 2. This returns the binary representation of the number as a string.
const decimalToBinary = decimal => decimal.toString(2);
decimalToBinary(2); // '10'
decimalToBinary(6); // '110'Luckily, BigInt.prototype.toString() works the same way, so you can create a similar function, or even reuse the same one, for BigInt values.
const bigIntToBinary = bigInt => bigInt.toString(2);
bigIntToBinary(2n); // '10'
bigIntToBinary(6n); // '110'
