Javascript reload all scripts

How to force a script reload and re-execute in Javascript?

Sometimes in a web development project, you may need to force a JavaScript script to reload and re-execute after a certain action has taken place. This can be necessary to update certain elements on the page, or to ensure that the script is running correctly after a modification has been made. There are several methods to achieve this, and each has its pros and cons. In this article, we will explore some of the most common ways to force a JavaScript script to reload and re-execute.

Method 1: Reload the Page

To force a script reload and re-execute using «Reload the Page» in Javascript, you can use the following steps:

window.addEventListener('beforeunload', function(event) < // Code to execute before the page is reloaded >);

window.addEventListener('beforeunload', function(event) < // Code to execute before the page is reloaded window.location.reload(true); >);

1. The window.location.reload() method is used to reload the page. The true parameter is used to force a reload from the server, rather than from the cache.

Here is a complete example:

window.addEventListener('beforeunload', function(event) < // Code to execute before the page is reloaded window.location.reload(true); >);

This example will reload the page whenever the user tries to navigate away from it. You can modify the event listener to trigger the reload in other ways, such as when a button is clicked or a certain condition is met.

Overall, this method is a simple and effective way to force a script reload and re-execute in Javascript.

Method 2: Use location.reload()

To reload and re-execute a script in JavaScript, you can use the location.reload() method. This method reloads the current document and all its resources, including scripts.

Here’s an example of how to use location.reload() to reload and re-execute a script:

// Define a function to be executed function myFunction()  console.log("Hello, world!"); > // Call the function myFunction(); // Reload and re-execute the script location.reload();

When you call location.reload() , the entire document will be reloaded, including the script that contains your function. The function will be redefined and can be called again.

If you want to reload the script without reloading the entire document, you can use the XMLHttpRequest object to fetch the script and then evaluate it using the eval() function. Here’s an example:

// Define a function to be executed function myFunction()  console.log("Hello, world!"); > // Call the function myFunction(); // Reload and re-execute the script using XMLHttpRequest and eval var xhr = new XMLHttpRequest(); xhr.open("GET", "myScript.js", true); xhr.onreadystatechange = function()  if (xhr.readyState === 4 && xhr.status === 200)  eval(xhr.responseText); > >; xhr.send();

In this example, we use XMLHttpRequest to fetch the script «myScript.js». When the script is loaded, we use eval() to evaluate it in the current context. This will redefine any functions or variables defined in the script, allowing you to execute them again.

Note that using eval() can be dangerous if you’re not careful, as it can execute arbitrary code. Make sure that you trust the source of the script that you’re evaluating.

In summary, location.reload() is a simple and effective way to reload and re-execute a script in JavaScript. If you need more control over the reloading process, you can use XMLHttpRequest and eval() to fetch and evaluate the script manually.

Method 3: Reload the Script Element

To force a script reload and re-execute in JavaScript, you can use the «Reload the Script Element» method. This method involves reloading the script element by removing it from the DOM and then re-adding it. Here’s how you can do it:

function reloadScript()  var script = document.querySelector('script[src="https://stacktuts.com/your-script.js"]'); var parent = script.parentNode; parent.removeChild(script); var newScript = document.createElement('script'); newScript.src = 'your-script.js'; parent.appendChild(newScript); >

In the above code, we first select the script element we want to reload using document.querySelector() . We then get its parent node using the parentNode property. We remove the script element from the DOM using removeChild() . We then create a new script element using document.createElement() , set its src attribute to the same script file, and add it back to the parent node using appendChild() .

You can call this function whenever you want to reload and re-execute the script. Here’s an example:

// Reload and re-execute the script every 5 seconds setInterval(reloadScript, 5000);

This will call the reloadScript() function every 5 seconds, effectively reloading and re-executing the script.

Note that this method may not work if the script has already been cached by the browser. In that case, you may need to add a cache-busting parameter to the script URL to force the browser to fetch a fresh copy of the script. For example:

newScript.src = 'your-script.js?' + Date.now();

This adds the current timestamp to the script URL, which will make it unique and prevent the browser from using a cached copy.

Method 4: Remove and Re-add the Script Element

To force a script reload and re-execute in Javascript, one way is to remove and re-add the script element. Here are the steps:

var script = document.querySelector('script[src="https://stacktuts.com/your-script.js"]'); var parent = script.parentNode;

var newScript = document.createElement('script'); newScript.src = 'your-script.js'; parent.appendChild(newScript);

Here’s the code in one block:

var script = document.querySelector('script[src="https://stacktuts.com/your-script.js"]'); var parent = script.parentNode; parent.removeChild(script); var newScript = document.createElement('script'); newScript.src = 'your-script.js'; parent.appendChild(newScript);

Note that this method may not work if the script relies on global variables or has side-effects that persist after execution. In those cases, you may need to manually reset the state of the script.

Method 5: Use window.location.href

To force a script reload and re-execute in JavaScript, you can use the window.location.href method. This method reloads the current page and re-executes all scripts on the page, including the one you want to reload. Here is how you can use it:

window.location.href = window.location.href;

This code sets the window.location.href property to the current URL, which triggers a reload of the page and re-executes all scripts on the page.

Another way to achieve the same result is to use the location.reload() method:

This code reloads the current page and re-executes all scripts on the page.

If you want to reload the page after a certain amount of time, you can use the setTimeout() function:

setTimeout(function()  window.location.href = window.location.href; >, 5000);

This code reloads the page after 5 seconds (5000 milliseconds).

You can also use the location.replace() method to reload the page and replace the current history entry:

location.replace(window.location.href);

This code replaces the current history entry with the new page, so the user cannot go back to the previous page using the browser’s back button.

In summary, to force a script reload and re-execute in JavaScript, you can use the window.location.href method or the location.reload() method. You can also use the setTimeout() function to reload the page after a certain amount of time, or the location.replace() method to replace the current history entry.

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How can I force clients to refresh JavaScript files?

This tutorial teaches us to force clients to refresh JavaScript files.

Now, the question is, why do we need to force clients to refresh the JavaScript files? Let’s understand it by example issue. Suppose we have deployed the application and lots of users are using our application. Now, to improve the performance and UI of the application, we will continuously work on our application and upgrade its version after every period. Obviously, after upgrading our application’s version, we will also push that into production. But sometimes, on the user’s screen, client-side JavaScript or CSS is not upgraded, and it shows the old version of our application even if we have pushed new code to the production environment.

Can you think about why this issue happens? Well, continue to read to know the answer. When users open our application in the browser for the first time, the browser stores the cache for that webpage in the local storage. So, when a user visits the webpage the next time from the same browser, it doesn’t take too much time to load due to the stored cache. So, in our case, the stored cache creates the issue. We have upgraded the application’s code to the production environment, but the browser takes the CSS and JavaScript files from the local storage, or we can say cache. Rather than reloading the new file from the server, the browser loads from the cache and shows the user the older version of the application.

We have explained some solutions below to reload the JavaScript files from the server after upgrading the application.

Hard Reload the Browser

The easiest solution is the hard reload your browser. Users can hard reload their browser by pressing ctrl + F5 or ctrl + shift + R after opening the application window. On the Mac, users can press the cmd + R. It will reload all files from the server again, and if you have updated JavaScript files, it will replace the upgraded file in the local cache of the client’s browser.

Another way to hard reload the browser is that press ctrl and click on the reload button in the top left of the browser. The Mac users must press the cmd key and click on the reload button.

Yay! This solution works as you do a hard reload; it reloads all files from the server. But is it good to tell the application users to reload their browser hard whenever upgrading the application? It is not a good practice. So, we came up the another best solution below.

Change the File Path in a Script Tag

In this approach, we will change the source URL in the JavaScript script tag to make the browser fool and reload the whole all changed files from the server again. We simply add some query parameters after the source URL of the file.

Users can follow the below syntax to edit the source URL in the source tag.

Syntax

Parameters

• version − Users can add any string as a version to keep track of the new version. The most general way is to add whatever version, but users can also add date and time to make it unique.

Example

The below example demonstrates how to append the date and time dynamically whenever version upgrades of our application.

 type="text/javascript"> //get the date and time var currentDate = (new Date()).getTime(); //create new script element var newScriptElement = document.createElement("script"); newScriptElement.type = "text/javascript"; // add current date to URL as a query parameter newScriptElement.src = "script.js?" + currentDate; // append new script element to body. document.body.appendChild(newScriptElement); 

Users can see that we have appended the date and time with the script file source URL in the above example. When a browser tries to find the script file with the updated URL, it will fail to get it from the local cache. After, the browser must need to reload it from the server.

In addition, the user can achieve this by editing the .htaccess file −

RewriteEngine On RewriteBase / RewriteCond %REQUEST_URI> \.(bmp|png|gif|css|js)$ [NC] RewriteCond %QUERY_STRING> !^(.+?&v50|)v=50[^&]*(?:&(.*)|)$ [NC] RewriteRule ^ %REQUEST_URI>?v=50 [R=301,L]

In such a way, we can make browsers auto-reload the JavaScript files whenever we push updates of our application to production.

It is not good practice to tell users to hard reload and clear cache to see a new version of client-side applications. So, developers can use the second approach to make it auto-reload all updated files by just adding the query parameter to the file path.

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How to force a script reload and re-execute with JavaScript?

Sometimes, we want to force a script reload and re-execute with JavaScript.

In this article, we’ll look at how to force a script reload and re-execute with JavaScript.

How to force a script reload and re-execute with JavaScript?

To force a script reload and re-execute with JavaScript, we can make a copy of the original script, remove it, and then append it again.

const scriptTag = document.createElement("script"); scriptTag.innerText = "document.body.innerHTML += 'Here again ---
';"; const head = document.getElementsByTagName("head")[0]; head.appendChild(scriptTag); setInterval(() => < head.removeChild(scriptTag); const newScriptTag = document.createElement("script"); newScriptTag.innerText = scriptTag.innerText; head.appendChild(newScriptTag); scriptTag = newScriptTag; >, 1000); 

We create the scriptTag with createElement .

And then we set its innerText property to add the script we want to run inside.

Next, we get the head element with getElementsByTagName .

Then we call head.appendChild with scriptTag to append it to the head.

In the setInterval callback, we remove the original scriptTag with head.removeChild .

Then we we recreate the script tag as newScriptTag and append it again to the head with head.appendChild .

Conclusion

To force a script reload and re-execute with JavaScript, we can make a copy of the original script, remove it, and then append it again.

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