@skhemata/skhemata-form/src/validator/lib/isDataURI.js

Skhemata Form Web Component. This web component can be used as base web component when working with forms and inputs.

import assertString from './util/assertString';

const validMediaType = /^[a-z]+\/[a-z0-9\-\+]+$/i;

const validAttribute = /^[a-z\-]+=[a-z0-9\-]+$/i;

const validData = /^[a-z0-9!\$&'\(\)\*\+,;=\-\._~:@\/\?%\s]*$/i;

export default function isDataURI(str) {
  assertString(str);
  let data = str.split(',');
  if (data.length < 2) {
    return false;
  }
  const attributes = data.shift().trim().split(';');
  const schemeAndMediaType = attributes.shift();
  if (schemeAndMediaType.substr(0, 5) !== 'data:') {
    return false;
  }
  const mediaType = schemeAndMediaType.substr(5);
  if (mediaType !== '' && !validMediaType.test(mediaType)) {
    return false;
  }
  for (let i = 0; i < attributes.length; i++) {
    if (i === attributes.length - 1 && attributes[i].toLowerCase() === 'base64') {
      // ok
    } else if (!validAttribute.test(attributes[i])) {
      return false;
    }
  }
  for (let i = 0; i < data.length; i++) {
    if (!validData.test(data[i])) {
      return false;
    }
  }
  return true;
}