How to Dynamically Load Internal Scripts In Order With Javascript

Question

I have several scripts I need to dynamically include in a specific order. I have looked at and tried several answers here: How to include multiple js files using jQuery $.getScript() method

My problem is that the answers here either don't work in my application due to loading the files asynchronously or greatly over complicating the matter due to loading external scripts. The scripts I need to dynamically load are internal. (ie: On my site's server)

In addition to many other attempts, Ive tried:

$.when(
            $.getScript('/1.js'),
            $.getScript('/2.js'),
            $.getScript('/3.js'),
            $.getScript('/4.js'),
            $.getScript('/5.js'),
            $.Deferred(function (deferred) {
                $(deferred.resolve);
            })
        ).done(function() {         
            //Do Something
        });

but this does not load the scripts in proper order and kicks out a slew of errors.

Furthermore, The scripts I need to load are internal and I dont see the need for all the AJAX

Ive also tried other variations to no avail and was hoping someone could illustrate how I could dynamically load internal scripts one after another, preferably without AJAX calls and over complicating?

Unless you can include the scripts in the HTML, which doesn't seem to be the case, you'll have to use Ajax or some network request to fetch them, right? — CertainPerformance
– CertainPerformance, Commented Nov 27, 2019 at 10:25
@CertainPerformance Im cloudy on the need for AJAX but if its necessary even for internal scripts that does shed light on the matter for me but Im still in the dark as to how to load these synchronously and would welcome & appreciate any guidance. I'm still reading elsewhere regardless. Thanks — Stuart
– Stuart, Commented Nov 27, 2019 at 10:27
If they have to be done in sequence then you would need to chain the $.getScript calls calls in the callback of each previous one. Are you using SPA architecture for the site? I ask as I'm trying to determine the reason for async loading of scripts; it's usually a lot more hassle than it's worth. — Rory McCrossan
– Rory McCrossan, Commented Nov 27, 2019 at 10:30
@RoryMcCrossan Im sorry, IDK what SPA Architecture is. Likely not. Just a handful of scripts that are dependent on each prior script. It works wonderfully by including them in HTML, The site just doesnt need them until a user clicks a button — Stuart
– Stuart, Commented Nov 27, 2019 at 10:36
Ah ok, so if this is being done for optimisation then it's not quite the correct approach. I'd suggest using bundling and minification of your JS (and CSS) instead. That way all scripts are loaded once and cached. Any subsequent page requests will then have no load time for the JS/CSS as they are cached. It also avoids the complexity of the AJAX requests you have to make, and also the loading stutters you'll get. — Rory McCrossan
– Rory McCrossan, Commented Nov 27, 2019 at 10:38

CertainPerformance · Accepted Answer · 2019-11-27 10:30:04Z

2

getScript returns a Promise-like object, so you can await each call of it in a loop for them to be processed in serial:

(async () => {
  for (const path of ['/1.js', '/2.js', '/3.js']) {
    await $.getScript(path);
  }
  // Do something
})()
  .catch((err) => {
    // Something went wrong
  });

answered Nov 27, 2019 at 10:30

CertainPerformance

373k55 gold badges354 silver badges359 bronze badges

Sign up to request clarification or add additional context in comments.

14 Comments

Stuart Over a year ago

I thank you immensely. Could I interest you in wrapping this in a similar manner to the $.when(... script I posted? Im not sure how to make sense of: "(async () => {" and be able to take a step

CertainPerformance Over a year ago

await can only be used inside an async function, thus the async and IIFE. Async functions return Promises, and the Promise will reject if any of the awaited items inside the function rejected, so .catch is needed on the outside to handle errors. You can also use try/catch inside the IIFE while awaiting, but .catch(ing the Promise looks a lot nicer IMO. You don't need to wrap this in $.when( or anything, that'll make things unnecessarily complicated; the code in the answer above should work as-is

Stuart Over a year ago

Awesome, Thanks. Im rolling up my sleeves now

Stuart Over a year ago

If you're "Performance" moniker is related to motorsports, You'll love my site. BTW, Since we are using AJAX and since Ive read that getScript does not cache, Is there a simple one liner we could add here so as to enable a users machine to cache these scripts for another day while they're at it?

CertainPerformance Over a year ago

Adding a caching mechanism would be a lot more complicated. You might store each script result in localStorage or something like that, and then check localStorage before calling getScript. Add a version number that gets bumped every time you change the script so that users download the most recent version instead of loading the old one from their local system.

|

Eugene · Accepted Answer · 2020-11-05 15:39:14Z

For anyone who is using jQuery I have improved @adeneo script so it will load all scripts in the specified order. It doesn't do chain loading, so it's very fast, but if you want even faster, change the 50 ms wait time.

$.getMultiScripts = function(arr, path) {

    function executeInOrder(scr, code, resolve) {
        // if its the first script that should be executed
        if (scr == arr[0]) {
            arr.shift();
            eval(code);
            resolve();
            console.log('executed', scr);
        } else {
            // waiting
            setTimeout(function(){
                executeInOrder(scr, code, resolve);
            }, 50);
        }
    }

    var _arr = $.map(arr, function(scr) {

        return new Promise((resolve) => {
            jQuery.ajax({
                type: "GET",
                url: (path || '') + scr,
                dataType: "text",
                success: function(code) {
                    console.log('loaded  ', scr);
                    executeInOrder(scr, code, resolve);
                },
                cache: true
            });
        });

    });
        
    _arr.push($.Deferred(function( deferred ){
        $( deferred.resolve );
    }));
        
    return $.when.apply($, _arr);
}

How to use:

var script_arr = [
    'myscript1.js', 
    'myscript2.js', 
    'myscript3.js'
];

$.getMultiScripts(script_arr, '/mypath/').done(function() {
    // all scripts loaded
});

Plush · Accepted Answer · 2019-11-27 10:59:16Z

-1

In pure js

['/1.js', '/2.js',  '/3.js', '/4.js', '/5.js'].forEach(function(script) {
    var scriptElement = document.createElement("script");
    scriptElement.src = script;

    // append script element where you want (head or body)
    document.head.appendChild(scriptElement);
});

answered Nov 27, 2019 at 10:59

Plush

1

Collectives™ on Stack Overflow

How to Dynamically Load Internal Scripts In Order With Javascript

3 Answers 3

14 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

14 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related