Is it possible to include a JavaScript file in another JavaScript file synchronously?

Question

Is it possible to include a JavaScript file in another JavaScript file synchronously?

Is there a way to import external JavaScript files into my HTML file without causing any issues? Similar to how @import works in CSS.

I've seen suggestions like appending a script tag to the DOM on websites like StackOverflow, but this method loads the files asynchronously. This becomes problematic when the order of the files is crucial - for example, if the second file relies on the first one. Loading jQuery before its dependencies might result in errors because jQuery hasn't finished loading yet.

Considering this, asynchronous loading doesn't seem suitable. Is there a method to synchronously load JavaScript files from another JavaScript file?

javascript dom

Answer 1

Answer №1

It is not possible to load JS files synchronously from within JS.

However, you can create a loader queue to handle this. Here's an example:

function ScriptLoader(queue) {
   this.started = false;
   this.queue = queue || [];
   this.currentIndex = 0;
   var self = this;
   this.next = function() {
     if(self.currentIndex == self.queue.length) return;
     self.load(self.queue[self.currentIndex]);
     self.currentIndex++;
   };
   this.load = function(dest) {
      var s = document.createElement('script');
      s.src = dest;
      document.getElementsByTagName('head')[0].appendChild(s);
      s.onload = self.next;
      if('onreadystatechange' in s) {
        s.onreadystatechange = function () {
          if (this.readyState == 'complete') {
             self.next();
          }
        }
      }
   };
}

ScriptLoader.prototype.start = function() {
    if(!this.started) {
       this.next();
       this.started = true;
    }
};

var loader = new ScriptLoader(['https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js', 'https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.9/jquery-ui.min.js', 'http://widgets.twimg.com/j/2/widget.js']);
loader.start();

In this scenario, the jQuery library is loaded first, followed by jQuery UI, and then the Twitter JS widget. :)

Answer 2

It is not possible to load JS files synchronously from within JS.

However, you can create a loader queue to handle this. Here's an example:

function ScriptLoader(queue) {
   this.started = false;
   this.queue = queue || [];
   this.currentIndex = 0;
   var self = this;
   this.next = function() {
     if(self.currentIndex == self.queue.length) return;
     self.load(self.queue[self.currentIndex]);
     self.currentIndex++;
   };
   this.load = function(dest) {
      var s = document.createElement('script');
      s.src = dest;
      document.getElementsByTagName('head')[0].appendChild(s);
      s.onload = self.next;
      if('onreadystatechange' in s) {
        s.onreadystatechange = function () {
          if (this.readyState == 'complete') {
             self.next();
          }
        }
      }
   };
}

ScriptLoader.prototype.start = function() {
    if(!this.started) {
       this.next();
       this.started = true;
    }
};

var loader = new ScriptLoader(['https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js', 'https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.9/jquery-ui.min.js', 'http://widgets.twimg.com/j/2/widget.js']);
loader.start();

In this scenario, the jQuery library is loaded first, followed by jQuery UI, and then the Twitter JS widget. :)

Answer 3

Answer №2

Consider exploring Webpack or Parcel for efficient bundling and loading of scripts. Utilizing pre-existing libraries like these can streamline your development process.

Answer 4

Consider exploring Webpack or Parcel for efficient bundling and loading of scripts. Utilizing pre-existing libraries like these can streamline your development process.

Is it possible to include a JavaScript file in another JavaScript file synchronously?

Answer №1

Answer №2

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