dangerousStyleValue.js

/**
 * Copyright 2013-2014, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule dangerousStyleValue
 * @typechecks static-only
 */

"use strict";

var CSSProperty = require('CSSProperty');

var isUnitlessNumber = CSSProperty.isUnitlessNumber;

/**
 * Convert a value into the proper css writable value. The style name `name`
 * should be logical (no hyphens), as specified
 * in `CSSProperty.isUnitlessNumber`.
 *
 * @param {string} name CSS property name such as `topMargin`.
 * @param {*} value CSS property value such as `10px`.
 * @return {string} Normalized style value with dimensions applied.
 */
function dangerousStyleValue(name, value) {
  // Note that we've removed escapeTextForBrowser() calls here since the
  // whole string will be escaped when the attribute is injected into
  // the markup. If you provide unsafe user data here they can inject
  // arbitrary CSS which may be problematic (I couldn't repro this):
  // https://www.owasp.org/index.php/XSS_Filter_Evasion_Cheat_Sheet
  // http://www.thespanner.co.uk/2007/11/26/ultimate-xss-css-injection/
  // This is not an XSS hole but instead a potential CSS injection issue
  // which has lead to a greater discussion about how we're going to
  // trust URLs moving forward. See #2115901

  var isEmpty = value == null || typeof value === 'boolean' || value === '';
  if (isEmpty) {
    return '';
  }

  var isNonNumeric = isNaN(value);
  if (isNonNumeric || value === 0 ||
      isUnitlessNumber.hasOwnProperty(name) && isUnitlessNumber[name]) {
    return '' + value; // cast to string
  }

  if (typeof value === 'string') {
    value = value.trim();
  }
  return value + 'px';
}

module.exports = dangerousStyleValue;