Encoding Helpers

encode-helpers.ts

/* If string supplied is prefixed with '0x' remove it and return the new string */
function stripHexPrefix(input: string): string {
  if (input.startsWith('0x')) {
    input = input.slice(2);
  }

  return input;
}

/* Convert a hexadecimal string to an array of hexadecimal byte values (in preparation of inserting into a byte array) */
function hexStringToByteArr(input: string): Uint8Array {
  input = stripHexPrefix(input);

  let arr: string[] = [];

  if (input.length % 2 === 0) {
    // if even number of hex digits -> input doesn't require prefixing for splitting into hex byte values
    arr = input.match(/.{1,2}/g)! as string[];
  } else {
    // if odd number of hex digits -> prefix with 0 digit before splitting into hex byte values
    arr = ('0' + input).match(/.{1,2}/g)! as string[];
  }

  // Convert hexadecimal value array to decimal value array
  const decimalArr = arr.map((h) => parseInt(h, 16));

  // Create byte array from decimal value array
  return Uint8Array.from(decimalArr);
}

/** Method to detect whether input is escaped hexadecimal sequence */
function isEscapedFormat(input: Input): boolean {
  if (typeof input === 'string') {
    return encodeURI(input[0]).startsWith('%');
  }

  return false;
}