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inserting jquery into js file

I have a js file that in which i want to include jquery. in order to include the jquery script i am using this clode:
var script = document.createElement('script');
script.src = 'https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js';
script.type = 'text/javascript';
document.getElementsByTagName('head')[0].appendChild(script);
this works, I can see that incuded the script correctly. My inspector shows that it loaded the script but jquery wont work.
any ideas?

You need to make sure the script you are dynamically loading is actually loaded before attempting to use it.
To do so, use script.onload to fire a callback once the load is completed.
var script = document.createElement('script');
script.src = 'https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js';
script.type = 'text/javascript';
document.getElementsByTagName('head') [0].appendChild(script);
script.onload = function () {
/* jquery dependent code here */
console.log($);
};
MDN has an example that's more adaptable to a callback you specify -
// from https://developer.mozilla.org/en-US/docs/Web/API/HTMLScriptElement#Dynamically_importing_scripts
function loadError (oError) {
throw new URIError("The script " + oError.target.src + " is not accessible.");
}
function importScript (sSrc, fOnload) {
var oScript = document.createElement("script");
oScript.type = "text\/javascript";
oScript.onerror = loadError;
if (fOnload) { oScript.onload = fOnload; }
document.currentScript.parentNode.insertBefore(oScript, document.currentScript);
oScript.src = sSrc;
}

Your jQuery code is not working may be caused by jQuery is not loaded yet while browser executing your jQuery code. Use function below to dynamically load jQuery with callback. Put your jQuery code inside a callback function.
function loadScript(url, callback) {
var s = document.createElement('script');
s.type = 'text/javascript';
s.src = url;
if (typeof(callback) === 'function') {
s.onload = s.onreadystatechange = function(event) {
event = event || window.event;
if (event.type === "load" || (/loaded|complete/.test(s.readyState))) {
s.onload = s.onreadystatechange = null;
callback();
}
};
}
document.body.appendChild(s);
}
/* Load up jQuery */
loadScript('https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js', function() {
// Put your jQuery code here.
});

You need to include jQuery inside the HTML code. jQuery won't work for you because your script is loaded before jQuery is loaded.

How to detect jquery is loaded when loading it dynamicly

I'm trying to load jquery to page if it's not loaded. I'll run some code right after loading it. With below code, i am trying to catch it when jquery is loaded.
My code loads jquery correctly but not raising onreadystatechange event.
if(typeof jQuery=='undefined') {
var headTag = document.getElementsByTagName("head")[0];
var jqTag = document.createElement('script');
jqTag.type = 'text/javascript';
jqTag.src = 'http://localhost:8001/jquery-min.js';
headTag.appendChild(jqTag);
jqTag.onreadystatechange= function () {
if (this.readyState == 'complete') {
this.loadWidget(containerId);
}
};
}
else {
this.loadWidget(containerId);
}
How can i catch it when jquery is loaded?

script tags have an onload event for when the script has loaded
if (typeof jQuery === 'undefined') {
var headTag = document.getElementsByTagName("head")[0];
var jqTag = document.createElement('script');
jqTag.type = 'text/javascript';
jqTag.onload = function() {
this.loadWidget(containerId);
}
jqTag.src = 'http://localhost:8001/jquery-min.js';
headTag.appendChild(jqTag);
} else {
this.loadWidget(containerId);
}

In my opinion your code is way too complicated.
Why not do what HTML5 boilerplate has done:
<script>window.jQuery || document.write('<script src="js/vendor/jquery-1.10.2.min.js"><\/script>')</script>
If the window.jQuery object isn't detected it elegantly fails over to write out the script tag to include it in native Javascript. You can, of course change the path to whatever you want.
Hope this helps.

why requirejs is not loading Dependencies?

after reading this hack
which cleared the concept of making jquery load before the dependencies.
I tweaked it for requrejs . console gives no error.
but both js files are getting loaded (fyjsfies) .
but not the requrejs dependencies .
i made my code something like this ..
(function (window, document, callback) {
var j, d;
var loaded = false;
if(!(j = window.require) || callback(j, loaded)) {
var script = document.createElement("script");
script.type = "text/javascript";
script.src = "full_https_path_myjsfile.js";
script.onload = script.onreadystatechange = function () {
if(!loaded && (!(d = this.readyState) || d == "loaded" || d == "complete")) {
callback((j = window.require).noConflict(1), loaded = true);
j(script).remove();
}
};
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = "myjsfile.js";
$("#someElement").append(script);
}
})(window, document, function ($, require_loaded) {
// Widget code here
alert('i m here');
require(["jquery", "model2", "model3", "model4"], function ($, model1, model2, model3) {});
});
alert is not being called why ???

You don't need this hack to load jQuery or anything else for that matter. You can configure RequireJS to alias dependencies to a path, especially those dependencies that are not formatted for RequireJS.
require.config({
paths : {
'jQuery' : 'path/to/jQuery.min.js'
}
});
require(['jQuery'],function($){
//jQuery is loaded
//$ is either the global jQuery or jQuery if it was AMD formatted
});

The problem is that the require script is added to the DOM but not loaded. Hence the onReadyStateChanged is not fired. to fix this, use document.documentElement.childNodes[0].appendChild(script) instead

Loading simple JS code after page loads?

Is there a way to load the JavaScript code (without placing it in the very bottom line of HTML document) after the page has been loaded? Here's the script example:
<script type="text/javascript" src="http://www.flickr.com/badge_code_v2.gne?count=10&display=latest&size=t&layout=x&source=user&user=XXX"></script>
PS. the reason is that the above Flickr code loads slowly and hangs the site meanwhile.

you can try it
<script type="text/javascript">
// Use any event to append the code
$(document).ready(function()
{
var s = document.createElement("script");
s.type = "text/javascript";
s.src = "test.js";
// Use any selector
$("head").append(s);
});
</script>
off course this will require jquery library or else you can paste this code on body's onload method
well this is something useful
It's not possible to synchronously execute a script at a URL. Note further that synchronous anything, when networks (or even file systems!) are involved is a Bad Idea. Someone, sometime, somewhere will be on a slow system, or a slow network, or both, and suddenly you've just hung their UI in the process.
http://bugs.jquery.com/ticket/6557
alternatively you can try
http://yepnopejs.com/

Apply it to the body's onload method.

If you want to load a script after the entire page has finished loading (including all the elements) try this. (jQuery)
$(window).load(function() {
var js,
id = 'SCRIPT-ID',
ref = document.getElementsByTagName('script')[0];
if (document.getElementById(id)) {
return;
}
js = document.createElement('script');
js.id = id;
js.async = true;
js.src = "http://www.website.com/script.js";
ref.parentNode.insertBefore(js, ref);
});
If you want it to load once the DOM is rendered, just change $(window) to $(document)

var asyncLoad = function (url) {
if (typeof url !== 'string') {
return false;
}
var script = document.createElement('script'),
firstScript = document.getElementsByTagName('script')[0];
script.setAttribute('src', url);
firstScript.parentNode.insertBefore(script, firstScript);
return script;
};
// or, for scriptless pages, just add to the head;
var asyncLoad = function (url) {
if (typeof url !== 'string') {
return false;
}
var script = document.createElement('script'),
head = document.getElementsByTagName('head')[0];
script.setAttribute('src', url);
head.appendChild(script);
return script;
};
// apply:
document.addEventListener('DOMContentLoaded', function () {
asyncLoad('script_url');
});

If you require modular execution of your scripts you can use following library
http://headjs.com/

How can I load jQuery if it is not already loaded?

I have a initializor.js that contains the following:
if(typeof jQuery=='undefined')
{
var headTag = document.getElementsByTagName("head")[0];
var jqTag = document.createElement('script');
jqTag.type = 'text/javascript';
jqTag.src = 'jquery.js';
headTag.appendChild(jqTag);
}
I am then including that file somewhere on another page. The code checks if jQuery is loaded, and if it isn't, adds it to the Head tag.
However, jQuery is not initializing, because in my main document, I have a few events declared just to test this. I also tried writing some jQuery code below the check, and Firebug said:
"jQuery is undefined".
Is there a way to do this? Firebug shows the jquery inclusion tag within the head tag!
Also, can I dynamically add code into the $(document).ready() event? Or wouldn't it be necessary just to add some Click events to a few elements?

jQuery is not available immediately as you are loading it asynchronously (by appending it to the <head>). You would have to add an onload listener to the script (jqTag) to detect when it loads and then run your code.
e.g.
function myJQueryCode() {
//Do stuff with jQuery
}
if(typeof jQuery=='undefined') {
var headTag = document.getElementsByTagName("head")[0];
var jqTag = document.createElement('script');
jqTag.type = 'text/javascript';
jqTag.src = 'jquery.js';
jqTag.onload = myJQueryCode;
headTag.appendChild(jqTag);
} else {
myJQueryCode();
}

To include jQuery you should use this:
<script src="//ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="jquery.js">\x3C/script>')</script>
it uses the Google CDN but provides a fallback an has a protocol relative URL.
Note: Be sure to change the version number to the latest version
if window.jQuery is defined, it will not continue to read the line since it is an or that already contains a true value, if not it wil (document.)write the value
see: theHTML5Boilerplate
also: you forgot the quotes, if jQuery is not defined:
typeof window.jQuery === "undefined" //true
typeof window.jQuery == undefined //false ,this is wrong
you could also:
window.jQuery === undefined //true

If you're in an async function, you could use await like this:
if(!window.jQuery){
let script = document.createElement('script');
document.head.appendChild(script);
script.type = 'text/javascript';
script.src = "//ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js";
await script.onload
}
/* Your jQuery code here */
If you're not, you can use (async function(){/*all the code*/})() to wrap and run all the code inside one
.
Alternatively, refactoring Adam Heath's answer (this is more readable IMO). Bottom line, you need to run the jQuery code AFTER jQuery finished loading.
jQueryCode = function(){
// your jQuery code
}
if(window.jQuery) jQueryCode();
else{
var script = document.createElement('script');
document.head.appendChild(script);
script.type = 'text/javascript';
script.src = "//ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js";
script.onload = jQueryCode;
}
Or you could also wrap it in a function to change the order of the code
function runWithJQuery(jQueryCode){
if(window.jQuery) jQueryCode();
else{
var script = document.createElement('script');
document.head.appendChild(script);
script.type = 'text/javascript';
script.src = "//ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js";
script.onload = jQueryCode;
}
}
runWithJQuery(function jQueryCode(){
// your jQuery code
})

The YepNope loader can be used to conditionally load scripts, has quite a nice, easy to read syntax, they have an example of just this on their website.
You can get it from their website.
Example taken from their website:
yepnope([{
load: 'http:/­/ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js',
complete: function () {
if (!window.jQuery) {
yepnope('local/jquery.min.js');
}
}
}

This site code is solved my problem.
function loadjQuery(url, success){
var script = document.createElement('script');
script.src = url;
var head = document.getElementsByTagName('head')[0],
done = false;
head.appendChild(script);
// Attach handlers for all browsers
script.onload = script.onreadystatechange = function() {
if (!done && (!this.readyState || this.readyState == 'loaded' || this.readyState == 'complete')) {
done = true;
success();
script.onload = script.onreadystatechange = null;
head.removeChild(script);
}
};
}
if (typeof jQuery == 'undefined'){
loadjQuery('http://code.jquery.com/jquery-1.10.2.min.js', function() {
// Write your jQuery Code
});
} else {
// jQuery was already loaded
// Write your jQuery Code
}
http://99webtools.com/blog/load-jquery-if-not-already-loaded/

This is old post but I create one workable solution tested on various places.
Here is the code.
<script type="text/javascript">
(function(url, position, callback){
// default values
url = url || 'https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js';
position = position || 0;
// Check is jQuery exists
if (!window.jQuery) {
// Initialize <head>
var head = document.getElementsByTagName('head')[0];
// Create <script> element
var script = document.createElement("script");
// Append URL
script.src = url;
// Append type
script.type = 'text/javascript';
// Append script to <head>
head.appendChild(script);
// Move script on proper position
head.insertBefore(script,head.childNodes[position]);
script.onload = function(){
if(typeof callback == 'function') {
callback(jQuery);
}
};
} else {
if(typeof callback == 'function') {
callback(jQuery);
}
}
}('https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js', 5, function($){
console.log($);
}));
</script>
Explanation you can find HERE.