JavaScript Spinlocks Explained

Question

JavaScript Spinlocks Explained

What is the best way to implement a spinlock in JavaScript?

I am attempting to load multiple images and I need to wait until all of them have finished loading before proceeding. My current approach involves using a spinlock like this:

for(...)
   image[i].onload = function() { ++imagesloaded; }

while(imagesloaded != totalimages)
{
}

However, this implementation crashes my browser. Is there a more efficient way to achieve this? Are there any alternative functions such as yield or sleep that I am overlooking?

javascript loops loader spinlock

Answer 1

Answer №1

Avoid using spinlocks at all costs.

Here is a method to handle image loading without resorting to spinlocks:

let imagesLoaded = 0;
const totalImages = 42;

function handleImageLoad()
{
    imagesLoaded++;
    if (imagesLoaded === totalImages)
    {
        doSomething();
    }
}

for (let i=0; i<totalImages; i++)
{
    image[i].onload = handleImageLoad;
}

When faced with the need to sleep or wait in JavaScript, consider utilizing callbacks and timers like setTimeout/setInterval.

Answer 2

Avoid using spinlocks at all costs.

Here is a method to handle image loading without resorting to spinlocks:

let imagesLoaded = 0;
const totalImages = 42;

function handleImageLoad()
{
    imagesLoaded++;
    if (imagesLoaded === totalImages)
    {
        doSomething();
    }
}

for (let i=0; i<totalImages; i++)
{
    image[i].onload = handleImageLoad;
}

When faced with the need to sleep or wait in JavaScript, consider utilizing callbacks and timers like setTimeout/setInterval.

Answer 3

Answer №2

The responses provided earlier may not be effective due to the necessity of spinlocks arising from browser limitations or bugs. An example is Safari, which currently (and hopefully not in future versions) mandates the use of the window.open method for file generation in JavaScript. This limitation means that generating a file with callbacks is impossible (due to popup blockers), thus requiring the implementation of a dialog window. This window first calls the file generation function (using callbacks) and then provides a button for downloading the file. As a result, the code must be modified as follows:

function process(callback) {
  processCallbackData = null; // global variable with unique name
  callback(function(data) {
     processCallbackData = data;
  });
}

function forwardButton() {
  if(processCallbackData != null) {
     goForwardUsingCallbackIncompatibleCode();
  } else {
     displayStillLoadingWarning();
  }
}

Answer 4

The responses provided earlier may not be effective due to the necessity of spinlocks arising from browser limitations or bugs. An example is Safari, which currently (and hopefully not in future versions) mandates the use of the window.open method for file generation in JavaScript. This limitation means that generating a file with callbacks is impossible (due to popup blockers), thus requiring the implementation of a dialog window. This window first calls the file generation function (using callbacks) and then provides a button for downloading the file. As a result, the code must be modified as follows:

function process(callback) {
  processCallbackData = null; // global variable with unique name
  callback(function(data) {
     processCallbackData = data;
  });
}

function forwardButton() {
  if(processCallbackData != null) {
     goForwardUsingCallbackIncompatibleCode();
  } else {
     displayStillLoadingWarning();
  }
}

Answer 5

Answer №3

Avoid using loops for checking. Instead, verify within the event handler function to ensure the check is done only when an image has finished loading, rather than repeatedly and rapidly.

Answer 6

Avoid using loops for checking. Instead, verify within the event handler function to ensure the check is done only when an image has finished loading, rather than repeatedly and rapidly.

JavaScript Spinlocks Explained

Answer №1

Answer №2

Answer №3

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