utils.js

// Copyright (c) 2013 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 Assertion support.
 */

/**
 * Simple common assertion API
 * @param {*} condition The condition to test.  Note that this may be used to
 *     test whether a value is defined or not, and we don't want to force a
 *     cast to Boolean.
 * @param {string=} opt_message A message to use in any error.
 */
function assert(condition, opt_message) {
  'use strict';
  if (!condition) {
    var msg = 'Assertion failed';
    if (opt_message)
      msg = msg + ': ' + opt_message;
    throw new Error(msg);
  }
}

/**
 * The global object.
 * @type {!Object}
 * @const
 */
var global = this;

/**
 * Alias for document.getElementById.
 * @param {string} id The ID of the element to find.
 * @return {HTMLElement} The found element or null if not found.
 */
function $(id) {
  return document.getElementById(id);
}

/**
 * Calls chrome.send with a callback and restores the original afterwards.
 * @param {string} name The name of the message to send.
 * @param {!Array} params The parameters to send.
 * @param {string} callbackName The name of the function that the backend calls.
 * @param {!Function} callback The function to call.
 */
function chromeSend(name, params, callbackName, callback) {
  var old = global[callbackName];
  global[callbackName] = function() {
    // restore
    global[callbackName] = old;

    var args = Array.prototype.slice.call(arguments);
    return callback.apply(global, args);
  };
  chrome.send(name, params);
}

/**
 * Generates a CSS url string.
 * @param {string} s The URL to generate the CSS url for.
 * @return {string} The CSS url string.
 */
function url(s) {
  // http://www.w3.org/TR/css3-values/#uris
  // Parentheses, commas, whitespace characters, single quotes (') and double
  // quotes (") appearing in a URI must be escaped with a backslash
  var s2 = s.replace(/(\(|\)|\,|\s|\'|\"|\\)/g, '\\$1');
  // WebKit has a bug when it comes to URLs that end with \
  // https://bugs.webkit.org/show_bug.cgi?id=28885
  if (/\\\\$/.test(s2)) {
    // Add a space to work around the WebKit bug.
    s2 += ' ';
  }
  return 'url("' + s2 + '")';
}

/**
 * Parses query parameters from Location.
 * @param {string} location The URL to generate the CSS url for.
 * @return {object} Dictionary containing name value pairs for URL
 */
function parseQueryParams(location) {
  var params = {};
  var query = unescape(location.search.substring(1));
  var vars = query.split('&');
  for (var i = 0; i < vars.length; i++) {
    var pair = vars[i].split('=');
    params[pair[0]] = pair[1];
  }
  return params;
}

/**
 * Call this to stop clicks on <a href="#"> links from scrolling to the top of
 * the page (and possibly showing a # in the link).
 */
function preventDefaultOnPoundLinkClicks() {
  document.addEventListener('click', function(e) {
    var anchor = findAncestor(e.target, function(el) {
      return el.tagName == 'A';
    });
    // Use getAttribute() to prevent URL normalization.
    if (anchor && anchor.getAttribute('href') == '#')
      e.preventDefault();
  });
}

// Handle click on a link. If the link points to a chrome: or file: url, then
// call into the browser to do the navigation.
/**
document.addEventListener('click', function(e) {
  if (e.defaultPrevented)
    return;

  var el = e.target;
  if (el.nodeType == Node.ELEMENT_NODE &&
      el.webkitMatchesSelector('A, A *')) {
    while (el.tagName != 'A') {
      el = el.parentElement;
    }

    if ((el.protocol == 'file:' || el.protocol == 'about:') &&
        (e.button == 0 || e.button == 1)) {
      chrome.send('navigateToUrl', [
        el.href,
        el.target,
        e.button,
        e.altKey,
        e.ctrlKey,
        e.metaKey,
        e.shiftKey
      ]);
      e.preventDefault();
    }
  }
});
**/