githubmirror/markdown-here

src/common/utils.js
528 строк16 KB
Adam Pritchard
Merge branch 'development' of github.com:adam-p/markdown-here into development
26 окт 2013, 06:33
26 окт 2013, 06:33bd53417
/*
 * Copyright Adam Pritchard 2013
 * MIT License : http://adampritchard.mit-license.org/
 */

/*
 * Utilities and helpers that are needed in multiple places.
 * If this module is being instantiated without a global `window` object being
 * available (providing XMLHttpRequest, for example), then `Utils.global` must
 * be set to an equivalent object by the caller.
 */

;(function() {

"use strict";
/*global module:false, chrome:false, safari:false*/


function consoleLog(logString) {
  if (typeof(console) !== 'undefined') {
    console.log(logString);
  }
  else {
    var consoleService = Components.classes['@mozilla.org/consoleservice;1']
                                   .getService(Components.interfaces.nsIConsoleService);
    consoleService.logStringMessage(logString);
  }
}

// TODO: Try to use `insertAdjacentHTML` for the inner and outer HTML functions.
// https://developer.mozilla.org/en-US/docs/Web/API/Element.insertAdjacentHTML

// Assigning a string directly to `element.innerHTML` is potentially dangerous:
// e.g., the string can contain harmful script elements. (Additionally, Mozilla
// won't let us pass validation with `innerHTML` assignments in place.)
// This function provides a safer way to append a HTML string into an element.
function saferSetInnerHTML(parentElem, htmlString) {
  // Jump through some hoops to avoid using innerHTML...

  var range = parentElem.ownerDocument.createRange();
  range.selectNodeContents(parentElem);

  var docFrag = range.createContextualFragment(htmlString);
  docFrag = sanitizeDocumentFragment(docFrag);

  range.deleteContents();
  range.insertNode(docFrag);
  range.detach();
}


// Approximating equivalent to assigning to `outerHTML` -- completely replaces
// the target element with `htmlString`.
// Note that some caveats apply that also apply to `outerHTML`:
// - The element must be in the DOM. Otherwise an exception will be thrown.
// - The original element has been removed from the DOM, but continues to exist.
//   Any references to it (such as the one passed into this function) will be
//   references to the original.
function saferSetOuterHTML(elem, htmlString) {
  if (!isElementinDocument(elem)) {
    throw new Error('Element must be in document');
  }

  var range = elem.ownerDocument.createRange();
  range.selectNode(elem);

  var docFrag = range.createContextualFragment(htmlString);
  docFrag = sanitizeDocumentFragment(docFrag);

  range.deleteContents();
  range.insertNode(docFrag);
  range.detach();
}


// Removes potentially harmful elements and attributes from `docFrag`.
// Returns a santized copy.
function sanitizeDocumentFragment(docFrag) {
  var i;

  // Don't modify the original
  docFrag = docFrag.cloneNode(true);

  var scriptTagElems = docFrag.querySelectorAll('script');
  for (i = 0; i < scriptTagElems.length; i++) {
    scriptTagElems[i].parentNode.removeChild(scriptTagElems[i]);
  }

  function cleanAttributes(node) {
    var i;

    if (typeof(node.removeAttribute) === 'undefined') {
      // We can't operate on this node
      return;
    }

    // Remove event handler attributes
    for (i = node.attributes.length-1; i >= 0; i--) {
      if (node.attributes[i].name.match(/^on/)) {
        node.removeAttribute(node.attributes[i].name);
      }
    }
  }

  walkDOM(docFrag.firstChild, cleanAttributes);

  return docFrag;
}


// Walk the DOM, executing `func` on each element.
// From Crockford.
function walkDOM(node, func) {
  func(node);
  node = node.firstChild;
  while(node) {
    walkDOM(node, func);
    node = node.nextSibling;
  }
}


function isElementinDocument(element) {
  var doc = element.ownerDocument;
  while (!!(element = element.parentNode)) {
    if (element === doc) {
      return true;
    }
  }
  return false;
}


// From: http://stackoverflow.com/a/3819589/729729
// Postbox doesn't support `node.outerHTML`.
function outerHTML(node, doc) {
  // if IE, Chrome take the internal method otherwise build one
  return node.outerHTML || (
    function(n){
        var div = doc.createElement('div'), h;
        div.appendChild(n.cloneNode(true));
        h = div.innerHTML;
        div = null;
        return h;
    })(node);
}


// From: http://stackoverflow.com/a/5499821/729729
var charsToReplace = {
  '&': '&amp;',
  '<': '&lt;',
  '>': '&gt;'
};

function replaceChar(char) {
  return charsToReplace[char] || char;
}

// An approximate equivalent to outerHTML for document fragments.
function getDocumentFragmentHTML(docFrag) {
  var html = '', i;
  for (i = 0; i < docFrag.childNodes.length; i++) {
    var node = docFrag.childNodes[i];
    if (node.nodeType === node.TEXT_NODE) {
      html += node.nodeValue.replace(/[&<>]/g, replaceChar);
    }
    else { // going to assume ELEMENT_NODE
      html += outerHTML(node, docFrag.ownerDocument);
    }
  }

  return html;
}


function isElementDescendant(parent, descendant) {
  var ancestor = descendant;
  while (!!(ancestor = ancestor.parentNode)) {
    if (ancestor === parent) {
      return true;
    }
  }

  return false;
}


// Take a URL that refers to a file in this extension and makes it absolute.
// Note that the URL *must not* be relative to the current path position (i.e.,
// no "./blah" or "../blah"). So `url` must start with `/`.
function getLocalURL(url) {
  if (url[0] !== '/') {
    throw 'relative url not allowed: ' + url;
  }

  if (url.indexOf('://') >= 0) {
    // already absolute
    return url;
  }

  if (typeof(chrome) !== 'undefined') {
    return chrome.extension.getURL(url);
  }
  else if (typeof(safari) !== 'undefined') {
    return safari.extension.baseURI + 'markdown-here/src' + url;
  }
  else {
    // Mozilla platform.
    // HACK The proper URL depends on values in `chrome.manifest`. But we "know"
    // that there are only a couple of locations we request from, so we're going
    // to branch depending on the presence of "common".

    var COMMON = '/common/';
    var CONTENT = '/firefox/chrome/';

    if (url.indexOf(COMMON) === 0) {
      return 'resource://markdown_here_common/' + url.slice(COMMON.length);
    }
    else if (url.indexOf(CONTENT) === 0) {
      return 'chrome://markdown_here/' + url.slice(CONTENT.length);
    }
  }

  throw 'unknown url type: ' + url;
}


// Makes an asynchrous XHR request for a local file (basically a thin wrapper).
// `mimetype` is optional. `callback` will be called with the responseText as
// argument.
// Throws exception on error. This should never happen.
function getLocalFile(url, mimetype, callback) {
  if (!callback) {
    // optional mimetype not provided
    callback = mimetype;
    mimetype = null;
  }

  var xhr = new Utils.global.XMLHttpRequest();
  if (mimetype) {
    xhr.overrideMimeType(mimetype);
  }
  xhr.open('GET', url);
  xhr.onreadystatechange = function() {
    if (this.readyState === this.DONE) {
      // Assume 200 OK -- it's just a local call
      callback(this.responseText);
    }
  };

  xhr.onerror = function(e) {
    // We're only requesting local files, so this should not happen.
    throw e;
  };

  xhr.send();
}


// Does async XHR request to get data at `url`, then passes it to `callback`
// Base64-encoded.
// Intended to be used get the logo image file in a form that can be put in a
// data-url image element.
// Throws exception on error. This should never happen.
function getLocalFileAsBase64(url, callback) {
  var xhr = new Utils.global.XMLHttpRequest();
  xhr.open('GET', url);
  xhr.responseType = 'arraybuffer';

  xhr.onload = function() {
    if (this.readyState === this.DONE) {
      // Assume 200 OK -- we only use this for local requests
      var uInt8Array = new Uint8Array(this.response);
      var i = uInt8Array.length;
      var binaryString = new Array(i);
      while (i--)
      {
        binaryString[i] = String.fromCharCode(uInt8Array[i]);
      }
      var data = binaryString.join('');

      var base64Data = Utils.global.btoa(data);

      callback(base64Data);
    }
  };

  xhr.onerror = function(e) {
    // We're only requesting local files, so this should not happen.
    throw e;
  };

  xhr.send();
}


// Events fired by Markdown Here will have this property set to true.
var MARKDOWN_HERE_EVENT = 'markdown-here-event';

// Fire a mouse event on the given element. (Note: not super robust.)
function fireMouseClick(elem) {
  var clickEvent = elem.ownerDocument.createEvent('MouseEvent');
  clickEvent.initMouseEvent(
    'click',
    false,                          // bubbles: We want to target this element and do not want the event to bubble.
    true,                           // cancelable
    elem.ownerDocument.defaultView, // view,
    1,                              // detail,
    0,                              // screenX
    0,                              // screenY
    0,                              // clientX
    0,                              // clientY
    false,                          // ctrlKey
    false,                          // altKey
    false,                          // shiftKey
    false,                          // metaKey
    0,                              // button
    null);                          // relatedTarget

  clickEvent[MARKDOWN_HERE_EVENT] = true;

  elem.dispatchEvent(clickEvent);
}


var PRIVILEGED_REQUEST_EVENT_NAME = 'markdown-here-request-event';

function makeRequestToPrivilegedScript(doc, requestObj, callback) {
  if (typeof(chrome) !== 'undefined') {
    // If `callback` is undefined and we pass it anyway, Chrome complains with this:
    // Uncaught Error: Invocation of form runtime.sendMessage(object, undefined, null) doesn't match definition runtime.sendMessage(optional string extensionId, any message, optional function responseCallback)
    if (callback) {
      chrome.runtime.sendMessage(requestObj, callback);
    }
    else {
      chrome.runtime.sendMessage(requestObj);
    }
  }
  else if (typeof(safari) !== 'undefined') {
    /*
    Unlike Chrome, Safari doesn't provide a way to pass a callback to a background-
    script request. Instead the background script sends a separate message to
    the content script. We'll keep a set of outstanding callbacks to process as
    the responses come in.
    */

    // If this is the first call, do some initialization.
    if (typeof(makeRequestToPrivilegedScript.requestCallbacks) === 'undefined') {
      makeRequestToPrivilegedScript.requestCallbacks = {};

      // Handle messages received from the background script.
      var backgroundMessageHandler = function(event) {
        // Note that this message handler will get triggered by any request sent
        // from the background script to the content script for a page, and
        // it'll get triggered once for each frame in the page. So we need to
        // make very sure that we should be acting on the message.
        if (event.name === 'request-response') {
          var responseObj = Utils.global.JSON.parse(event.message);

          if (responseObj.requestID &&
              makeRequestToPrivilegedScript.requestCallbacks[responseObj.requestID]) {
            // Call the stored callback.
            makeRequestToPrivilegedScript.requestCallbacks[responseObj.requestID](responseObj.response);
            // And remove the stored callback.
            delete makeRequestToPrivilegedScript.requestCallbacks[responseObj.requestID];
          }
        }
      };
      safari.self.addEventListener('message', backgroundMessageHandler, false);
    }

    // Store the callback for later use in the response handler.
    if (callback) {
      var reqID = Math.random();
      makeRequestToPrivilegedScript.requestCallbacks[reqID] = callback;
      requestObj.requestID = reqID;
    }

    safari.self.tab.dispatchMessage('request', Utils.global.JSON.stringify(requestObj));
  }
  else {
    // See: https://developer.mozilla.org/en-US/docs/Code_snippets/Interaction_between_privileged_and_non-privileged_pages#Chromium-like_messaging.3A_json_request_with_json_callback

    // Make a unique event name to use. (Bad style to modify the input like this...)
    requestObj.responseEventName = 'markdown-here-response-event-' + Math.floor(Math.random()*1000000);

    var request = doc.createTextNode(JSON.stringify(requestObj));

    var responseHandler = function(event) {
      var response = null;

      // There may be no response data.
      if (request.nodeValue) {
        response = JSON.parse(request.nodeValue);
      }

      request.parentNode.removeChild(request);

      if (callback) {
        callback(response);
      }
    };

    request.addEventListener(requestObj.responseEventName, responseHandler, false);

    (doc.head || doc.body).appendChild(request);

    var event = doc.createEvent('HTMLEvents');
    event.initEvent(PRIVILEGED_REQUEST_EVENT_NAME, true, false);
    request.dispatchEvent(event);
  }
}


// Gives focus to the element.
// Setting focus into elements inside iframes is not simple.
function setFocus(elem) {
  // We need to do some tail-recursion focus setting up through the iframes.
  if (elem.document) {
    // This is a window
    if (elem.frameElement) {
      // This is the window of an iframe. Set focus to the parent window.
      setFocus(elem.frameElement.ownerDocument.defaultView);
    }
  }
  else if (elem.ownerDocument.defaultView.frameElement) {
    // This element is in an iframe. Set focus to its owner window.
    setFocus(elem.ownerDocument.defaultView);
  }

  elem.focus();
}


// Gets the URL of the top window that elem belongs to.
// May recurse up through iframes.
function getTopURL(win, justHostname) {
  if (win.frameElement) {
    // This is the window of an iframe
    return getTopURL(win.frameElement.ownerDocument.defaultView);
  }

  var url;
  // We still want a useful value if we're in Thunderbird, etc.
  if (!win.location.href || win.location.href === 'about:blank') {
    url = win.navigator.userAgent.match(/Thunderbird|Postbox'/);
    if (url) {
      url = url[0];
    }
  }
  else if (justHostname) {
    url = win.location.hostname;
  }
  else {
    url = win.location.href;
  }

  return url;
}


// Sets a short timeout and then calls callback
function nextTick(callback, context) {
  var runner = function() {
    callback.call(context);
  };

  Utils.global.setTimeout(runner, 0);
}

// `context` is optional. Will be `this` when `callback` is called.
function nextTickFn(callback, context) {
  return function() {
    var args = arguments;
    var runner = function() {
      callback.apply(context, args);
    };

    Utils.global.setTimeout(runner, 0);
  };
}


// Expose these functions
var Utils = {};

// For some reason the other two ways of creating properties don't work.
Utils.__defineSetter__('global', function(val) { Utils._global = val; });
Utils.__defineGetter__('global', function() {
  if (typeof(Utils._global) === 'function') {
    return Utils._global.call();
  }
  return Utils._global;
});
Utils.global = this;

Utils.saferSetInnerHTML = saferSetInnerHTML;
Utils.saferSetOuterHTML = saferSetOuterHTML;
Utils.sanitizeDocumentFragment = sanitizeDocumentFragment;
Utils.getDocumentFragmentHTML = getDocumentFragmentHTML;
Utils.isElementDescendant = isElementDescendant;
Utils.getLocalURL = getLocalURL;
Utils.getLocalFile = getLocalFile;
Utils.getLocalFileAsBase64 = getLocalFileAsBase64;
Utils.fireMouseClick = fireMouseClick;
Utils.MARKDOWN_HERE_EVENT = MARKDOWN_HERE_EVENT;
Utils.makeRequestToPrivilegedScript = makeRequestToPrivilegedScript;
Utils.PRIVILEGED_REQUEST_EVENT_NAME = PRIVILEGED_REQUEST_EVENT_NAME;
Utils.consoleLog = consoleLog;
Utils.setFocus = setFocus;
Utils.getTopURL = getTopURL;
Utils.nextTick = nextTick;
Utils.nextTickFn = nextTickFn;


var EXPORTED_SYMBOLS = ['Utils'];

if (typeof module !== 'undefined') {
  module.exports = Utils;
} else {
  this.Utils = Utils;
  this.EXPORTED_SYMBOLS = EXPORTED_SYMBOLS;
}

}).call(function() {
  return this || (typeof window !== 'undefined' ? window : global);
}());