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Adding page in a certain space of my homepage

This is my first question on stackoverflow.
I want to load a different page in a certain space of my homepage. I tried it with JavaScript many times but hitting a wall. I can do it with iframe. But I was thinking if there is any other way to do it. And I want to load the page when the user clicks the link.
The way I did it is like this:
document.getElementById('aboutUs').onclick = function() {
document.getElementById('newDiv').style.display = "none";
document.getElementById('iFrame').style.display = "block";
}
Thank You!!!

You need to make request to load the static content.
Hope this snippet will be useful
//A generic function to load the static page
function loadContent(target, staticPageLoc) {
var r = new XMLHttpRequest(); // making request to load the static page
r.open("GET", staticPageLoc, true);
r.onreadystatechange = function () {
if (r.readyState != 4 || r.status != 200) return;
target.innerHTML = ""; // removing any previous content
target.innerHTML = r.responseText; // response will be the static page
};
r.send();
}
document.getElementById('aboutUs').onclick = function() {
loadContent(document.getElementById('id of dom element where page will load'), 'page path')
}
Alternately you can explore jquery.load function & better to run it in a server or else you may come across CORS

How to recognize that one js file loaded?

I try to display progress bar when page loading. I want change width of progress bar after js files loaded .At the final after load all documents set with of progress bar to 100% .Now I need to recognize js files loading with javascript.
Is this possible ? Please advice.

For internal js files loading recognition:
As functions and variables can be accessed from another file you can set the value of global progress variable and display it's value by calling the function
//on page or head js file
var progress = 0;
function displayProgress()
{
//show progress based on 'progress' variable
}
//file1.js
progress += 10;
displayProgress();
...
//file2.js
progress += 20;
displayProgress();
...
For external js files there is good article. The main idea is to periodically check existense of external functions (typeof fixpng =='function') and if it exist - stop checking and display progress.
Here's the JavaScript code to load the external library with a
callback passed in:
function loadExtScript(src, callback) { var s = document.createElement('script'); s.src = src; document.body.appendChild(s); // if loaded...call the callback }
Firefox allows you to listen for the onload event on the script
element:
s.onload = callback;
With Internet Explorer you can wait for a state change on the script
element:
s.onreadystatechange = function() { if ( this.readyState != "loaded"
) return; callback.call(); }
The problem comes with Safari - there's no event change for Safari, so
we can't tell when the script has loaded. This is the solution I came
up with (and this solution should also work with Opera):
function loadExtScript(src, test, callback) { var s =
document.createElement('script'); s.src = src;
document.body.appendChild(s);
var callbackTimer = setInterval(function() {
var call = false;
try {
call = test.call();
} catch (e) {}
if (call) {
clearInterval(callbackTimer);
callback.call();
} }, 100); }
The function takes a test as a parameter. Since you are the designer
of the app, you'll know what successful test is. Once this test is
true, it will execute the callback. A simple test could be to check
whether a function exists, for example:
loadExtScript('/fixpng.js', function() { return (typeof fixpng ==
'function'); }, myCallbackFunction);

If you know at least one defined namespace (almost all libraries and plugins have it: e.g. jQuery, jQuery.ui, jQuery.mobile, toastr, DataTable, etc.) or one global variable name introduced by the script files which are being loaded, then you can do this:
(function(undefined) {
var scriptFilesLoaded = false,
files = [],
timer = setInterval(function(){
try {
files = [
jQuery,
jQuery.mobile,
jQuery.ui,
someGlobalVariableName
];
if(files.indexOf(undefined)<0){
scriptFilesLoaded = true;
clearInterval(timer);
}
}
catch(e) {
console.warn('Preloader in action: Script files not loaded yet.');
}
},200);
})();
It doesn't matter if the script file is remote or local.

Multiple calls to ajax script not working

I am very new (literally less than a few days) to all things ajax, but it is required for a form I am building for my employer.
Basically, no matter what I do it just will not work for more than one function. To elaborate, I am trying to update 4 different parts of a page based on one drop down using onchange. Now updating one part works fine, updating any more than that fails... but not only fails, it also fails if for example I do call to ajax part, then just a simple alert... but if I do it with the alert first it works, then falls over again if I put anything after the ajax call. I hope that makes sense. It also works if I do, for example onchange, and onblur on the same element, it will execute twice. I'll post the code then hopefully it will make more sense.
<select name="pType" id="ptype" onchange="dostuff()">
So that's the input element...
<script type="text/javascript">
function dostuff(){
ajaxpage('adminincludes/popoptions.php?pID=<?= $sql['pID']; ?>&pType=' + ptype.value,'options');
alert('test');
}
</script>
...and that's the dostuff code, or an example anyway, ignore the PHP part as it fails regardless of that, that part works fine.
Now the rest of the code is within an external file and I believe that somewhere in there is where the problem lies... however I am new to ajax, and am not the greatest with js as I have never really had a major need for it so just learned what I needed, when I needed.
var bustcachevar = 1 //bust potential caching of external pages after initial request? (1=yes, 0=no)
var loadedobjects = ""
var rootdomain = "http://" + window.location.hostname
var bustcacheparameter = ""
function ajaxpage(url, containerid) {
var page_request = false
if (window.XMLHttpRequest) // if Mozilla, Safari etc
page_request = new XMLHttpRequest()
else if (window.ActiveXObject) { // if IE
try {
page_request = new ActiveXObject("Msxml2.XMLHTTP")
} catch (e) {
try {
page_request = new ActiveXObject("Microsoft.XMLHTTP")
} catch (e) {}
}
} else
return false
page_request.onreadystatechange = function () {
loadpage(page_request, containerid)
}
if (bustcachevar) //if bust caching of external page
bustcacheparameter = (url.indexOf("?") != -1) ? "&" + new Date().getTime() : "?" + new Date().getTime()
page_request.open('GET', url + bustcacheparameter, true)
page_request.send(null)
page_request.send(null)
}
function loadpage(page_request, containerid) {
if (page_request.readyState == 4 && (page_request.status == 200 || window.location.href.indexOf("http") == -1)) document.getElementById(containerid).innerHTML = page_request.responseText
}
function loadobjs() {
if (!document.getElementById) return
for (i = 0; i < arguments.length; i++) {
var file = arguments[i]
var fileref = ""
if (loadedobjects.indexOf(file) == -1) { //Check to see if this object has not already been added to page before proceeding
if (file.indexOf(".js") != -1) { //If object is a js file
fileref = document.createElement('script')
fileref.setAttribute("type", "text/javascript");
fileref.setAttribute("src", file);
} else if (file.indexOf(".css") != -1) { //If object is a css file
fileref = document.createElement("link")
fileref.setAttribute("rel", "stylesheet");
fileref.setAttribute("type", "text/css");
fileref.setAttribute("href", file);
}
}
if (fileref != "") {
document.getElementsByTagName("head").item(0).appendChild(fileref)
loadedobjects += file + " " //Remember this object as being already added to page
}
}
}
Now like I said, the code works perfectly when only calling ajaxpage() once, or multiple times via different events, it just will not work multiple times from one event, even when putting the multiple instances into the dostuff() function.
Any help would be greatly appreciated as this is really starting to aggravate me.
UPDATE: This isn't as urgent now as i have done a "workaround" which uses multiple events such as mouseover, mouseout etc on an update link instead. which means it works as i need it to, however it is not elegant by any means and I am still intrigued why it won't work when called multiple times within 1 event?!

I notice on lines 26 and 27 of your sample you're repeating:
page_request.send(null)
Worth eliminating that before you continue. Could we see a live link to this anywhere so we can perhaps examine generated source?

conditionally loading external javascript libraries in my plugin

I have written a plugin that depends on external libraries that I want to include conditionally, that is, the user can choose to not have them be included automatically in case the user's web site already has those libraries. Here is some pseudocode to illustrate the issue
<script type="text/javascript" src="path/to/plugin.js"></script>
<script type="text/javascript">
PLUGIN.init({
"param1": "foo",
"parma2": 33,
"include": {"jquery": 0, "googlemaps": 0}
});
</script>
In my plugin script
var PLUGIN = {
"init": function(obj) {
if (obj.include.googlemaps !== 0) {
document.write('<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true&v=3.6">\x3C/script>');
}
if (obj.include.jquery !== 0) {
document.write('<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.js">\x3C/script>');
}
.. do more things ..
}
The problem is that when I am ready to "do more things," the libraries don't seem to be loaded yet. I get an error that jquery not found, or google maps not found. I can solve this by changing my code to
document.write('<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true&v=3.6">\x3C/script>');
document.write('<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.js">\x3C/script>');
var PLUGIN = {
"init": function(obj) {
.. do more things ..
}
but now the user can't control loading the libraries or not loading them. Suggestions? Workarounds?
Update: Thanks for the suggestions, you all, but no joy so far. Here is what I am doing, and what is happening. Since I am potentially loading 0 or more scripts (the user can optionally decide which scripts need not be loaded), I have made my code like so
"importLib": function(libPath, callback) {
var newLib = document.createElement("script");
if (callback !== null) {
newLib.onload = callback;
}
newLib.src = libPath;
document.head.appendChild(newLib);
},
"init": function(obj) {
var scripts = [];
if (obj.include.googlemaps !== 0) {
scripts.push("http://maps.google.com/maps/api/js?sensor=true&v=3.6");
}
if (obj.include.jquery !== 0) {
scripts.push("http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.js");
}
if (obj.include.anotherlib !== 0) {
scripts.push("http://path/to/another/lib.js");
}
var len_scripts = scripts.length,
callback = null;
if (len_scripts > 0) {
for (var i = 0; i < len_scripts; i++) {
// add callback only on the last lib to be loaded
if (i == len_scripts - 1) {
callback = function() { startApp(obj) };
}
importLib(scripts[i], callback);
}
}
// Start the app rightaway if no scripts need to be loaded
else {
startApp(obj);
}
},
"startApp": function(obj) {
}
What happens is that Firefox croaks with a attempt to run compile-and-go script on a cleared scope error, and Safari doesn't get that error, but doesn't load anything. Funnily, Safari error console shows no error at all. Seems like the Firefox error is caused by the line document.head.appendChild(newLib); which, if I comment, the error goes away, but of course, the web page doesn't load correctly.

You should add each script as a DOM node and use the onload attribute to take action when it has completed loading.
function importLib(libPath, callback) {
var newLib = document.createElement("script");
newLib.onload = callback;
newLib.src = libPath;
document.head.appendChild(newLib);
}
Above, the libPath argument is the URL of the library, and the callback argument is a function to call when loading is complete. You could use it as follows:
importLib("http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.js", function() {
alert("jquery loaded!");
nowDoSomething(aboutIt);
});
By the way: in general, document.write is not a good solution for most problems (but I won't say never the right solution -- there are exceptions to every rule).

the above solution would work in modern browsers but for IE 7/8 u might wanna added little extra code, something like this:
function importLib(libPath, callback) {
var newLib = document.createElement("script");
if (navigator.userAgent.indexOf('MSIE') !== -1) {
newLib.onreadystatechange = function () {// this piece is for IE 7 and 8
if (this.readyState == 'complete') {
callback();
}
};
} else {
newLib.onload = callback;
}
newLib.src = libPath;
document.head.appendChild(newLib);
}

I encountered the same issue. One workaround if you are writing your site in .NET is by conditionally writing the script reference before the page loads from the code behind. My issue is when remote users access my app over VPN, it blocks access to the internet, thus google maps cannot be referenced. This prevents the rest of the page from loading within a reasonable timeframe. I tried controlling the script reference of the google maps library via jQuery's getScript() command, but as you found out, the subsequent google maps configuration code runs before the external library is referenced.
My solution was to conditionally reference google maps from code behind instead:
VB (code behind):
'if VPN mode is not enable, add the external google maps script reference (this speeds up the interface when using VPN significantly)
If Session("VPNMode") = False Then
Dim sb As System.Text.StringBuilder = New System.Text.StringBuilder()
sb.AppendLine("")
sb.AppendLine("<script type='text/javascript'")
sb.Append(" src='http://maps.google.com/maps/api/js?v=3&sensor=false'>")
sb.Append("</script>")
Dim header As LiteralControl = New LiteralControl
header.Text = sb.ToString()
Me.Page.Header.Controls.Add(header)
End If
Client side script (javascript):
<script type='text/javascript'>
$(function () {
if ($("input[name*='VPN']").is(":checked"))
{ }
else {
loadGoogleMap()
}
});
function loadGoogleMap() {
hazsite = new google.maps.LatLng(hazLat, hazLong);
map = new google.maps.Map(document.getElementById('map_canvas'), { zoom: 18, center: hazsite, mapTypeId: google.maps.MapTypeId.SATELLITE });
var marker = new google.maps.Marker({
position: hazsite,
map: map,
title: "Site Location"
});
}
</script>

Verify External Script Is Loaded

I'm creating a jquery plugin and I want to verify an external script is loaded. This is for an internal web app and I can keep the script name/location consistent(mysscript.js). This is also an ajaxy plugin that can be called on many times on the page.
If I can verify the script is not loaded I'll load it using:
jQuery.getScript()
How can I verify the script is loaded because I don't want the same script loaded on the page more than once? Is this something that I shouldn't need to worry about due to caching of the script?
Update:
I may not have control over who uses this plugin in our organization and may not be able to enforce that the script is not already on the page with or without a specific ID, but the script name will always be in the same place with the same name. I'm hoping I can use the name of the script to verify it's actually loaded.

If the script creates any variables or functions in the global space you can check for their existance:
External JS (in global scope) --
var myCustomFlag = true;
And to check if this has run:
if (typeof window.myCustomFlag == 'undefined') {
//the flag was not found, so the code has not run
$.getScript('<external JS>');
}
Update
You can check for the existence of the <script> tag in question by selecting all of the <script> elements and checking their src attributes:
//get the number of `<script>` elements that have the correct `src` attribute
var len = $('script').filter(function () {
return ($(this).attr('src') == '<external JS>');
}).length;
//if there are no scripts that match, the load it
if (len === 0) {
$.getScript('<external JS>');
}
Or you can just bake this .filter() functionality right into the selector:
var len = $('script[src="<external JS>"]').length;

Few too many answers on this one, but I feel it's worth adding this solution. It combines a few different answers.
Key points for me were
add an #id tag, so it's easy to find, and not duplicate
Use .onload() to wait until the script has finished loading before using it
mounted() {
// First check if the script already exists on the dom
// by searching for an id
let id = 'googleMaps'
if(document.getElementById(id) === null) {
let script = document.createElement('script')
script.setAttribute('src', 'https://maps.googleapis.com/maps/api/js?key=' + apiKey)
script.setAttribute('id', id)
document.body.appendChild(script)
// now wait for it to load...
script.onload = () => {
// script has loaded, you can now use it safely
alert('thank me later')
// ... do something with the newly loaded script
}
}
}

#jasper's answer is totally correct but with modern browsers, a standard Javascript solution could be:
function isScriptLoaded(src)
{
return Boolean(document.querySelector('script[src="' + src + '"]'));
}
UPDATE July 2021:
The accepted solutions above have changed & improved much over time. The scope of my previous answer above was only to detect if the script was inserted in the document to load (and not whether the script has actually finished loading).
To detect if the script has already loaded, I use the following method (in general):
Create a common library function to dynamically load all scripts.
Before loading, it uses the isScriptLoaded(src) function above to check whether the script has already been added (say, by another module).
I use something like the following loadScript() function to load the script that uses callback functions to inform the calling modules if the script finished loading successfully.
I also use additional logic to retry when script loading fails (in case of temporary network issues).
Retry is done by removing the <script> tag from the body and adding it again.
If it still fails to load after configured number of retries, the <script> tag is removed from the body.
I have removed that logic from the following code for simplicity. It should be easy to add.
/**
* Mark/store the script as fully loaded in a global variable.
* #param src URL of the script
*/
function markScriptFullyLoaded(src) {
window.scriptLoadMap[src] = true;
}
/**
* Returns true if the script has been added to the page
* #param src URL of the script
*/
function isScriptAdded(src) {
return Boolean(document.querySelector('script[src="' + src + '"]'));
}
/**
* Returns true if the script has been fully loaded
* #param src URL of the script
*/
function isScriptFullyLoaded(src) {
return src in window.scriptLoadMap && window.scriptLoadMap[src];
}
/**
* Load a script.
* #param src URL of the script
* #param onLoadCallback Callback function when the script is fully loaded
* #param onLoadErrorCallback Callback function when the script fails to load
* #param retryCount How many times retry laoding the script? (Not implimented here. Logic goes into js.onerror function)
*/
function loadScript(src, onLoadCallback, onLoadErrorCallback, retryCount) {
if (!src) return;
// Check if the script is already loaded
if ( isScriptAdded(src) )
{
// If script already loaded successfully, trigger the callback function
if (isScriptFullyLoaded(src)) onLoadCallback();
console.warn("Script already loaded. Skipping: ", src);
return;
}
// Loading the script...
const js = document.createElement('script');
js.setAttribute("async", "");
js.src = src;
js.onload = () => {
markScriptFullyLoaded(src)
// Optional callback on script load
if (onLoadCallback) onLoadCallback();
};
js.onerror = () => {
// Remove the script node (to be able to try again later)
const js2 = document.querySelector('script[src="' + src +'"]');
js2.parentNode.removeChild(js2);
// Optional callback on script load failure
if (onLoadErrorCallback) onLoadErrorCallback();
};
document.head.appendChild(js);
}

This was very simple now that I realize how to do it, thanks to all the answers for leading me to the solution. I had to abandon $.getScript() in order to specify the source of the script...sometimes doing things manually is best.
Solution
//great suggestion #Jasper
var len = $('script[src*="Javascript/MyScript.js"]').length;
if (len === 0) {
alert('script not loaded');
loadScript('Javascript/MyScript.js');
if ($('script[src*="Javascript/MyScript.js"]').length === 0) {
alert('still not loaded');
}
else {
alert('loaded now');
}
}
else {
alert('script loaded');
}
function loadScript(scriptLocationAndName) {
var head = document.getElementsByTagName('head')[0];
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = scriptLocationAndName;
head.appendChild(script);
}

Create the script tag with a specific ID and then check if that ID exists?
Alternatively, loop through script tags checking for the script 'src' and make sure those are not already loaded with the same value as the one you want to avoid ?
Edit: following feedback that a code example would be useful:
(function(){
var desiredSource = 'https://sitename.com/js/script.js';
var scripts = document.getElementsByTagName('script');
var alreadyLoaded = false;
if(scripts.length){
for(var scriptIndex in scripts) {
if(!alreadyLoaded && desiredSource === scripts[scriptIndex].src) {
alreadyLoaded = true;
}
}
}
if(!alreadyLoaded){
// Run your code in this block?
}
})();
As mentioned in the comments (https://stackoverflow.com/users/1358777/alwin-kesler), this may be an alternative (not benchmarked):
(function(){
var desiredSource = 'https://sitename.com/js/script.js';
var scripts = document.getElementsByTagName('script');
var alreadyLoaded = false;
for(var scriptIndex in document.scripts) {
if(!alreadyLoaded && desiredSource === scripts[scriptIndex].src) {
alreadyLoaded = true;
}
}
if(!alreadyLoaded){
// Run your code in this block?
}
})();

Simply check if the global variable is available, if not check again. In order to prevent the maximum callstack being exceeded set a 100ms timeout on the check:
function check_script_loaded(glob_var) {
if(typeof(glob_var) !== 'undefined') {
// do your thing
} else {
setTimeout(function() {
check_script_loaded(glob_var)
}, 100)
}
}

Another way to check an external script is loaded or not, you can use data function of jquery and store a validation flag. Example as :
if(!$("body").data("google-map"))
{
console.log("no js");
$.getScript("https://maps.googleapis.com/maps/api/js?v=3.exp&sensor=false&callback=initilize",function(){
$("body").data("google-map",true);
},function(){
alert("error while loading script");
});
}
}
else
{
console.log("js already loaded");
}

I think it's better to use window.addEventListener('error') to capture the script load error and try to load it again.
It's useful when we load scripts from a CDN server. If we can't load script from the CDN, we can load it from our server.
window.addEventListener('error', function(e) {
if (e.target.nodeName === 'SCRIPT') {
var scriptTag = document.createElement('script');
scriptTag.src = e.target.src.replace('https://static.cdn.com/', '/our-server/static/');
document.head.appendChild(scriptTag);
}
}, true);

Merging several answers from above into an easy to use function
function GetScriptIfNotLoaded(scriptLocationAndName)
{
var len = $('script[src*="' + scriptLocationAndName +'"]').length;
//script already loaded!
if (len > 0)
return;
var head = document.getElementsByTagName('head')[0];
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = scriptLocationAndName;
head.appendChild(script);
}

My idead is to listen the error log if there is an error on script loading.
const checkSegmentBlocked = (e) => {
if (e.target.nodeName === 'SCRIPT' && e.target.src.includes('analytics.min.js')) {
window.isSegmentBlocked = true;
e.target.removeEventListener(e.type, checkSegmentBlocked);
}
};
window.addEventListener('error', checkSegmentBlocked, true);

Some answers on this page are wrong. They check for the existence of the <script> tag - but that is not enough. That tells you that the tag was inserted into the DOM, not that the script is finished loading.
I assume from the question that there are two parts: the code that inserts the script, and the code that checks whether the script has loaded.
The code that dynamically inserts the script:
let tag = document.createElement('script');
tag.type = 'text/javascript';
tag.id = 'foo';
tag.src = 'https://cdn.example.com/foo.min.js';
tag.onload = () => tag.setAttribute('data-loaded', true); // magic sauce
document.body.appendChild(tag);
Some other code, that checks whether the script has loaded:
let script = document.getElementById('foo');
let isLoaded = script && script.getAttribute('data-loaded') === 'true';
console.log(isLoaded); // true
If the both of those things (inserting and checking) are in the same code block, then you could simplify the above:
tag.onload = () => console.log('loaded');

I found a quick tip before you start diving into code that might save a bit of time. Check devtools on the webpage and click on the network tab. The js scripts are shown if they are loaded as a 200 response from the server.