suggest.js

AJAX and PHP: Building Responsive Web Applications源代码

/* URL to the PHP page called for receiving suggestions for a keyword*/
var getFunctionsUrl = "suggest.php?keyword=";
/* URL for seeing the results for the selected suggestion */
var phpHelpUrl="http://www.php.net/manual/en/function.";
/* the keyword for which an HTTP request has been initiated */
var httpRequestKeyword = "";
/* the last keyword for which suggests have been requested */
var userKeyword = "";
/* number of suggestions received as results for the keyword */
var suggestions = 0;
/* the maximum number of characters to be displayed for a suggestion */
var suggestionMaxLength = 30;
/* flag that indicates if the up or down arrow keys were pressed
   the last time a keyup event occurred  */
var isKeyUpDownPressed = false;
/* the last suggestion that has been used for autocompleting the keyword */
var autocompletedKeyword = "";
/* flag that indicates if there are results for the current requested keyword*/
var hasResults = false;
/* the identifier used to cancel the evaluation with the clearTimeout method. */
var timeoutId = -1;
/* the currently selected suggestion (by arrow keys or mouse)*/
var position = -1;
/* cache object containing the retrieved suggestions for different keywords */
var oCache = new Object();
/* the minimum and maximum position of the visible suggestions */
var minVisiblePosition = 0;
var maxVisiblePosition = 9;
// when set to true, display detailed error messages
var debugMode = true;
/* the XMLHttp object for communicating with the server */
var xmlHttpGetSuggestions = createXmlHttpRequestObject();
/* the onload event is handled by our init function */
window.onload = init;

// creates an XMLHttpRequest instance
function createXmlHttpRequestObject() 
{
  // will store the reference to the XMLHttpRequest object
  var xmlHttp;
  // this should work for all browsers except IE6 and older
  try
  {
    // try to create XMLHttpRequest object
    xmlHttp = new XMLHttpRequest();
  }
  catch(e)
  {
    // assume IE6 or older
    var XmlHttpVersions = new Array("MSXML2.XMLHTTP.6.0",
                                    "MSXML2.XMLHTTP.5.0",
                                    "MSXML2.XMLHTTP.4.0",
                                    "MSXML2.XMLHTTP.3.0",
                                    "MSXML2.XMLHTTP",
                                    "Microsoft.XMLHTTP");
    // try every prog id until one works
    for (var i=0; i<XmlHttpVersions.length && !xmlHttp; i++) 
    {
      try 
 
      { 
        // try to create XMLHttpRequest object
        xmlHttp = new ActiveXObject(XmlHttpVersions[i]);
      } 
      catch (e) {}
    }
  }
  // return the created object or display an error message
  if (!xmlHttp)
    alert("Error creating the XMLHttpRequest object.");
  else 
    return xmlHttp;
}

/* function that initializes the page */
function init() 
{  
  // retrieve the input control for the keyword
  var oKeyword = document.getElementById("keyword");    
  // prevent browser from starting the autofill function
  oKeyword.setAttribute("autocomplete", "off");  
  // reset the content of the keyword and set the focus on it
  oKeyword.value = "";
  oKeyword.focus();
  // set the timeout for checking updates in the keyword's value
  setTimeout("checkForChanges()", 500);
} 

/* function that adds to a keyword an array of values */
function addToCache(keyword, values)
{
  // create a new array entry in the cache
  oCache[keyword] = new Array();
  // add all the values to the keyword's entry in the cache
  for(i=0; i<values.length; i++)
    oCache[keyword][i] = values[i];
}

/* 
   function that checks to see if the keyword specified as parameter is in 
   the cache or tries to find the longest matching prefixes in the cache 
   and adds them in the cache for the current keyword parameter
*/
function checkCache(keyword)
{
  // check to see if the keyword is already in the cache
  if(oCache[keyword])
    return true;
  // try to find the biggest prefixes
  for(i=keyword.length-2; i>=0; i--)
  {
    // compute the current prefix keyword 
    var currentKeyword = keyword.substring(0, i+1);
    // check to see if we have the current prefix keyword in the cache
    if(oCache[currentKeyword])
    {            
      // the current keyword's results already in the cache
      var cacheResults = oCache[currentKeyword];
      // the results matching the keyword in the current cache results
      var keywordResults = new Array();
      var keywordResultsSize = 0;            
      // try to find all matching results starting with the current prefix
      for(j=0;j<cacheResults.length;j++)
      {
 
        if(cacheResults[j].indexOf(keyword) == 0)               
          keywordResults[keywordResultsSize++] = cacheResults[j];
      }      
      // add all the keyword's prefix results to the cache
      addToCache(keyword, keywordResults);      
      return true;  
    }
  }
  // no match found
  return false;
}

/* initiate HTTP request to retrieve suggestions for the current keyword */
function getSuggestions(keyword) 
{  
  /* continue if keyword isn't null and the last pressed key wasn't up or 
     down */
  if(keyword != "" && !isKeyUpDownPressed)
  {
    // check to see if the keyword is in the cache
    isInCache = checkCache(keyword);
    // if keyword is in cache...
    if(isInCache == true)          
    {   
      // retrieve the results from the cache          
      httpRequestKeyword=keyword;
      userKeyword=keyword;     
      // display the results in the cache
      displayResults(keyword, oCache[keyword]);                          
    }
    // if the keyword isn't in cache, make an HTTP request
    else    
    {    
      if(xmlHttpGetSuggestions)
      { 
        try
        {
          /* if the XMLHttpRequest object isn't busy with a previous
             request... */
          if (xmlHttpGetSuggestions.readyState == 4 || 
              xmlHttpGetSuggestions.readyState == 0) 
          {    
            httpRequestKeyword = keyword;
            userKeyword = keyword;
            xmlHttpGetSuggestions.open("GET", 
                                getFunctionsUrl + encode(keyword), true);
            xmlHttpGetSuggestions.onreadystatechange = 
                                                handleGettingSuggestions; 
            xmlHttpGetSuggestions.send(null);
          }
          // if the XMLHttpRequest object is busy...
          else
          {
            // retain the keyword the user wanted             
            userKeyword = keyword;
            // clear any previous timeouts already set
            if(timeoutId != -1)
              clearTimeout(timeoutId);          
            // try again in 0.5 seconds     
            timeoutId = setTimeout("getSuggestions(userKeyword);", 500);
          }
        }
        catch(e)
 
        {
          displayError("Can't connect to server:\n" + e.toString());
        }
      }
    }    
  }
}

/* transforms all the children of an xml node into an array */
function xmlToArray(resultsXml)
{
  // initiate the resultsArray
  var resultsArray= new Array();  
  // loop through all the xml nodes retrieving the content  
  for(i=0;i<resultsXml.length;i++)
    resultsArray[i]=resultsXml.item(i).firstChild.data;
  // return the node's content as an array
  return resultsArray;
}

/* handles the server's response containing the suggestions 
   for the requested keyword  */
function handleGettingSuggestions() 
{
  //if the process is completed, decide what to do with the returned data
  if (xmlHttpGetSuggestions.readyState == 4) 
  {
    // only if HTTP status is "OK"
    if (xmlHttpGetSuggestions.status == 200) 
    { 
      try
      {
        // process the server's response
        updateSuggestions();
      }
      catch(e)
      {
        // display the error message
        displayError(e.toString()); 
      }  
    } 
    else
    {
      displayError("There was a problem retrieving the data:\n" + 
                   xmlHttpGetSuggestions.statusText);
    }       
  }
}

/* function that processes the server's response */
function updateSuggestions()
{
  // retrieve the server's response 
  var response = xmlHttpGetSuggestions.responseText;
  // server error?
  if (response.indexOf("ERRNO") >= 0 
      || response.indexOf("error:") >= 0
      || response.length == 0)
    throw(response.length == 0 ? "Void server response." : response);
  // retrieve the document element
  response = xmlHttpGetSuggestions.responseXML.documentElement;
  // initialize the new array of functions' names
  nameArray = new Array();
  // check to see if we have any results for the searched keyword
 
  if(response.childNodes.length)
  {
    /* we retrieve the new functions' names from the document element as 
       an array */
    nameArray= xmlToArray(response.getElementsByTagName("name"));       
  }
  // check to see if other keywords are already being searched for
  if(httpRequestKeyword == userKeyword)    
  {
    // display the results array
    displayResults(httpRequestKeyword, nameArray);
  }
  else
  {
    // add the results to the cache
    // we don't need to display the results since they are no longer useful
    addToCache(httpRequestKeyword, nameArray);              
  }
}

/* populates the list with the current suggestions */
function displayResults(keyword, results_array) 
{  
  // start building the HTML table containing the results  
  var div = "<table>"; 
  // if the searched for keyword is not in the cache then add it to the cache
  if(!oCache[keyword] && keyword)
    addToCache(keyword, results_array);
  // if the array of results is empty display a message
  if(results_array.length == 0)
  {
    div += "<tr><td>No results found for <strong>" + keyword + 
           "</strong></td></tr>";
    // set the flag indicating that no results have been found 
    // and reset the counter for results
    hasResults = false;
    suggestions = 0;
  }
  // display the results
  else
  {
    // resets the index of the currently selected suggestion
    position = -1;
    // resets the flag indicating whether the up or down key has been pressed
    isKeyUpDownPressed = false;
    /* sets the flag indicating that there are results for the searched 
       for keyword */
    hasResults = true;
    // get the number of results from the cache
    suggestions = oCache[keyword].length;
    // loop through all the results and generate the HTML list of results
    for (var i=0; i<oCache[keyword].length; i++) 
    {  
      // retrieve the current function