chrome/browser/resources/settings/prefs/pref_util.js

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/** @fileoverview Utility functions to help use prefs in Polymer controls. */

// TODO(michaelpg): converge with other WebUI on capitalization. This is
// consistent with Settings, but WebUI uses lower.underscore_case.
cr.define('Settings.PrefUtil', function() {
  /**
   * Converts a string value to a type corresponding to the given preference.
   * @param {string} value
   * @param {!chrome.settingsPrivate.PrefObject} pref
   * @return {boolean|number|string|undefined}
   */
  function stringToPrefValue(value, pref) {
    switch (pref.type) {
      case chrome.settingsPrivate.PrefType.BOOLEAN:
        return value == 'true';
      case chrome.settingsPrivate.PrefType.NUMBER:
        const n = parseInt(value, 10);
        if (isNaN(n)) {
          console.error(
              'Argument to stringToPrefValue for number pref ' +
              'was unparsable: ' + value);
          return undefined;
        }
        return n;
      case chrome.settingsPrivate.PrefType.STRING:
      case chrome.settingsPrivate.PrefType.URL:
        return value;
      default:
        assertNotReached('No conversion from string to ' + pref.type + ' pref');
    }
  }

  /**
   * Returns the value of the pref as a string.
   * @param {!chrome.settingsPrivate.PrefObject} pref
   * @return {string}
   */
  function prefToString(pref) {
    switch (pref.type) {
      case chrome.settingsPrivate.PrefType.BOOLEAN:
      case chrome.settingsPrivate.PrefType.NUMBER:
        return pref.value.toString();
      case chrome.settingsPrivate.PrefType.STRING:
      case chrome.settingsPrivate.PrefType.URL:
        return /** @type {string} */ (pref.value);
      default:
        assertNotReached('No conversion from ' + pref.type + ' pref to string');
    }
  }
  return {
    stringToPrefValue: stringToPrefValue,
    prefToString: prefToString,
  };
});