metamask-extension/shared/modules/utils.js

import { MAX_SAFE_CHAIN_ID } from '../constants/network'

/**
 * Checks whether the given number primitive chain ID is safe.
 * Because some cryptographic libraries we use expect the chain ID to be a
 * number primitive, it must not exceed a certain size.
 *
 * @param {number} chainId - The chain ID to check for safety.
 * @returns {boolean} Whether the given chain ID is safe.
 */
export function isSafeChainId(chainId) {
  return (
    Number.isSafeInteger(chainId) && chainId > 0 && chainId <= MAX_SAFE_CHAIN_ID
  )
}

/**
 * Checks whether the given value is a 0x-prefixed, non-zero, non-zero-padded,
 * hexadecimal string.
 *
 * @param {any} value - The value to check.
 * @returns {boolean} True if the value is a correctly formatted hex string,
 * false otherwise.
 */
export function isPrefixedFormattedHexString(value) {
  if (typeof value !== 'string') {
    return false
  }
  return /^0x[1-9a-f]+[0-9a-f]*$/iu.test(value)
}