Adding select menu default value via JS?
i'm developing a meta search engine website, Soogle and i've used JS to populate select menu..
Now, after the page is loaded none of engines is loaded by default, user needs to select it on his own or [TAB] to it..
Is there a possibility to preselect one value from the menu via JS after the page loads?
This is the code:
Javascript:
// SEARCH FORM INIT
function addOptions(){
var sel=document.searchForm.whichEngine;
for(var i=0,l=arr.length;i<l;i++){
sel.options[i]=new Option(arr[i][0], i);
}
}
function startSearch(){
var searchString=document.searchForm.searchText.value;
if(searchString.replace(/\s+/g,"").length > 0){
var searchEngine=document.searchForm.whichEngine.selectedIndex,
finalSearchString=arr[searchEngine][1]+searchString;
window.location=finalSearchString;
}
return false;
}
function checkKey(e){
var key = e.which ? e.which : event.keyCode;
if(key === 13){
return startSearch();
}
}
// SEARCH ENGINES INIT
var arr = [
["Web", "http://www.google.com/search?q="],
["Images", "http://images.google.com/images?q="],
["Knowledge","http://en.wikipedi开发者_StackOverflowa.org/wiki/Special:Search?search="],
["Videos","http://www.youtube.com/results?search_query="],
["Movies", "http://www.imdb.com/find?q="],
["Torrents", "http://thepiratebay.org/search/"]
];
HTML:
<body onload="addOptions();document.forms.searchForm.searchText.focus()">
<div id="wrapper">
<div id="logo"></div>
<form name="searchForm" method="POST" action="javascript:void(0)">
<input name="searchText" type="text" onkeypress="checkKey(event);"/>
<span id="color"></span>
<select tabindex="1" name="whichEngine" selected="Web"></select>
<br />
<input tabindex="2" type="button" onClick="return startSearch()" value="Search"/>
</form>
</div>
</body>
I appreciate that your question asks for a solution that utilises JavaScript, but having looked at the webpage in question I feel confident in making this point:
Your problem is that you are trying to use JavaScript for something that HTML itself was designed to solve:
<select name="whichEngine">
<option value="http://www.google.com/search?q=" selected="selected">Web</option>
<option value="http://images.google.com/images?q=">Images</option>
<option value="http://en.wikipedia.org/wiki/Special:Search?search=">Knowledge</option>
<option value="http://www.youtube.com/results?search_query=">Videos</option>
<option value="http://www.imdb.com/find?q=">Movies</option>
<option value="http://thepiratebay.org/search/">Torrents</option>
</select>
Fear not, though! You can still access all of the options from JavaScript in the same way that you did before.
function alertSelectedEngine() {
var e = document.getElementsByName("whichEngine")[0];
alert("The user has selected: "+e.options[e.selectedIndex].text+" ("+e.options[e.selectedIndex].value+")");
}
Please, forgive and listen to me.
I have modified the code to use jQuery. It is working fine in IE8, IE8 (Compatibility mode) and in FireFox.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Index</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript">
// SEARCH ENGINES INIT
var arr = new Array();
arr[arr.length] = new Array("Web", "http://www.google.com/search?q=");
arr[arr.length] = new Array("Images", "http://images.google.com/images?q=");
arr[arr.length] = new Array("Knoweledge", "http://en.wikipedia.org/wiki/Special:Search?search=");
arr[arr.length] = new Array("Videos", "http://www.youtube.com/results?search_query=");
arr[arr.length] = new Array("Movies", "http://www.imdb.com/find?q=");
arr[arr.length] = new Array("Torrents", "http://thepiratebay.org/search/");
// SEARCH FORM INIT
function addOptions() {
// Add the options to the select dropdown.
var nOptions = arr.length;
var optionText = '';
for (var i = 0; i < nOptions; i++) {
optionText += '<option value="' + i + '">' + arr[i][0] + '</option>'
}
//alert('optionText = ' + optionText);
// Add the options to the select drop down.
$('select#whichEngine').html(optionText);
// set the second option as default. This can be changed, if required.
$('select#whichEngine option:eq(1)').attr('selected', true);
}
function startSearch() {
var searchEngineIndex = $('select#whichEngine option:selected').attr('value');
searchEngineIndex = parseInt(searchEngineIndex, 10);
var searchString = $('input#searchText').val();
if (searchEngineIndex >= 0 && searchString) {
var searchURL = arr[searchEngineIndex][1] + searchString;
//alert('location = ' + searchURL);
window.location.href = searchURL;
}
return false;
}
function checkKey(e) {
var character = (e.which) ? e.which : event.keyCode;
if (character == '13') {
return startSearch();
}
}
$(function() {
// Add the options to the select drop down.
addOptions();
// Add focus to the search text box.
$('input#searchText').focus();
// Hook the click event handler to the search button.
$('input[type=button]').click(startSearch);
$('input#searchText').keyup(checkKey);
});
</script>
</head>
<body>
<div id="wrapper">
<div id="logo"></div>
<form name="searchForm" method="POST" action="javascript:void(0)">
<input id="searchText" name="searchText" type="text"/>
<span id="color"></span>
<select tabindex="1" id="whichEngine" name="whichEngine"></select>
<br />
<input tabindex="2" type="button"value="Search"/>
</form>
</div>
</body>
</html>
You had some errors in how you handle the <select> values and options. I would reorganize your JavaScript like this:
// SEARCH ENGINES
var arr = [["Web", "http://www.google.com/search?q="],
["Images", "http://images.google.com/images?q="],
["Knowledge", "http://en.wikipedia.org/wiki/Special:Search?search="],
["Videos", "http://www.youtube.com/results?search_query="],
["Movies", "http://www.imdb.com/find?q="],
["Torrents", "http://thepiratebay.org/search/"]];
// SEARCH FORM INIT
function addOptions(){
var sel=document.searchForm.whichEngine;
for(var i=0;i<arr.length;i++) {
sel.options[i]=new Option(arr[i][0],arr[i][1]);
}
}
function startSearch(){
var searchString = document.searchForm.searchText.value;
if(searchString!==''){
var mySel = document.searchForm.whichEngine;
var finalLocation = mySel.options[mySel.selectedIndex].value;
finalLocation += encodeURIComponent(searchString);
location.href = finalLocation;
}
return false;
}
function checkKey(e){
var character=(e.which) ? e.which : event.keyCode;
return (character=='13') ? startSearch() : null;
}
I would also move your onload handler into the main body of your JavaScript:
window.onload = function() {
addOptions();
document.searchForm.searchText.focus();
};
I also made some changes to your HTML:
<body>
<div id="wrapper">
<div id="logo"></div>
<form name="searchForm" method="POST" action="." onsubmit="return false;">
<input name="searchText" type="text" onkeypress="checkKey(event);" />
<span id="color"></span>
<select tabindex="1" name="whichEngine" selected="Web"></select><br />
<input tabindex="2" type="button" value="Search"
onclick="startSearch();" />
</form>
</div>
</body>
You could specify which egine you would like preselected in the engines array like this:
// SEARCH ENGINES INIT
// I've used array literals for brevity
var arr = [
["Web", "http://www.google.com/search?q="],
["Images", "http://images.google.com/images?q="],
["Knoweledge", "http://en.wikipedia.org/wiki/Special:Search?search="],
/*
* notice that this next line has an extra element which is set to true
* this is my default
*/
["Videos", "http://www.youtube.com/results?search_query=", true],
["Movies", "http://www.imdb.com/find?q="],
["Torrents", "http://thepiratebay.org/search/"]
];
Then in your setup function:
// SEARCH FORM INIT
function addOptions() {
var sel = document.searchForm.whichEngine;
for (var i = 0; i < arr.length; i++) {
// notice the extra third argument to the Option constructor
sel.options[i] = new Option( arr[i][0], i, arr[i][2] );
}
}
if your only concern is preselecting an engine onload, don't "over-engineer" it.
var Web = "http://www.google.com/search?q=";
var Images = "http://images.google.com/images?q=";
var Knowledge = "http://en.wikipedia.org/wiki/Special:Search?search=";
var Videos = "http://www.youtube.com/results?search_query=";
var Movies = "http://www.imdb.com/find?q=";
var Torrents = "http://thepiratebay.org/search/";
function addOptions(source){
var sel=document.searchForm.whichEngine;
for(var i=0,l=arr.length;i<l;i++){
sel.options[i]=new Option(arr[i][0], i);
}
}
then insert your argument made onto your body tag to a pre-defined variable. If you want something random, create a new function with your equation for selecting a random variable then load your addOptions(function) within your new function. Then remove addOptions from your body tag.
<body onload="addOptions(Web);document.forms.searchForm.searchText.focus()">
加载中,请稍侯......
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