Can we ensure that the function is called when a node is located?

Question

Can we ensure that the function is called when a node is located?

Presently, I am executing the following code but it is causing the call stack to slow down; how can I optimize this using either an async await or more advanced promise functions? I have a dynamic node that is added to the DOM at different times depending on various load times - instead of continuously checking like in the example below, is there a way to handle this more efficiently with async await somehow?

function checkForNode() { 
    let coolNode= document.getElementById("CoolDomNode");
    if (coolNode) {
        doManyThings(coolNode);
    } else { 
        checkForNode()
    }
}

javascript asynchronous ecmascript-6 async-await

Answer 1

Answer №1

Since this is not an asynchronous task, using async/await will not solve the issue. Instead, consider utilizing setTimeout to prevent recursion from occurring on the same stack. By incorporating setTimeout, you can introduce a delay between each iteration to reduce CPU usage. Here's an example:

checkForNode() { 
  let coolNode = document.getElementById("CoolDomNode");

  if (coolNode) {
    doManyThings(coolNode);
  } else { 
    setTimeout(checkForNode, 500);  // To run as frequently as possible, set the delay to 0
  }
}

By the way, your current approach aligns with what MutationObserver excels at handling. This method informs you when DOM tree modifications occur. You can define a root element, and whenever a new element is appended below the root, a callback function will be triggered:

var observer = new MutationObserver(function(mutations) {             
  mutations.forEach(function(mutation) {                              
    mutation.addedNodes.forEach(function(addedNode) {                 
      if(addedNode.id === "CoolDomNode") {                            
        doManyThings(addedNode);                                     
      }
    });
  });
});

observer.observe(document.body, { childList: true, subtree: true });

Answer 2

Since this is not an asynchronous task, using async/await will not solve the issue. Instead, consider utilizing setTimeout to prevent recursion from occurring on the same stack. By incorporating setTimeout, you can introduce a delay between each iteration to reduce CPU usage. Here's an example:

checkForNode() { 
  let coolNode = document.getElementById("CoolDomNode");

  if (coolNode) {
    doManyThings(coolNode);
  } else { 
    setTimeout(checkForNode, 500);  // To run as frequently as possible, set the delay to 0
  }
}

By the way, your current approach aligns with what MutationObserver excels at handling. This method informs you when DOM tree modifications occur. You can define a root element, and whenever a new element is appended below the root, a callback function will be triggered:

var observer = new MutationObserver(function(mutations) {             
  mutations.forEach(function(mutation) {                              
    mutation.addedNodes.forEach(function(addedNode) {                 
      if(addedNode.id === "CoolDomNode") {                            
        doManyThings(addedNode);                                     
      }
    });
  });
});

observer.observe(document.body, { childList: true, subtree: true });

Answer 3

Answer №2

Although using a MutationObserver is typically the recommended approach for handling these types of situations, there is an alternative method that may still be relevant in some cases.

This method leverages the fact that preceding nodes are accessible to a script before subsequent nodes, allowing you to place a script after the node (or within it) to access the node and its contents:

<div id="CoolDomNode">Hello</div>
<script>
    document.getElementById("CoolDomNode");
    /// or
    document.currentScript.previousElementSibling;
</script>

You can consider which solution aligns better with your needs and rationale. Monitoring the document for changes incurs a linear cost increase based on the number of nodes present, which may outweigh the benefit of waiting specifically for one node. On the other hand, inserting a script after the desired node could be perceived as cluttering the HTML structure, and this approach assumes the node is already part of the document.

Answer 4

Although using a MutationObserver is typically the recommended approach for handling these types of situations, there is an alternative method that may still be relevant in some cases.

This method leverages the fact that preceding nodes are accessible to a script before subsequent nodes, allowing you to place a script after the node (or within it) to access the node and its contents:

<div id="CoolDomNode">Hello</div>
<script>
    document.getElementById("CoolDomNode");
    /// or
    document.currentScript.previousElementSibling;
</script>

You can consider which solution aligns better with your needs and rationale. Monitoring the document for changes incurs a linear cost increase based on the number of nodes present, which may outweigh the benefit of waiting specifically for one node. On the other hand, inserting a script after the desired node could be perceived as cluttering the HTML structure, and this approach assumes the node is already part of the document.

Can we ensure that the function is called when a node is located?

Answer №1

Answer №2

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