Category: JavaScript

Sometimes, we want to check if a setInterval timer is running and stop it with JavaScript.

In this article, we’ll look at how to check if a setInterval timer is running and stop it with JavaScript.

How to check if a setInterval timer is running and stop it with JavaScript?

To check if a setInterval timer is running and stop it with JavaScript, we can call clearIntveral with the timer variable.

For instance, we write:

<button>
  stop
</button>

to add a button.

Then we write:

const interval = setInterval(() => {
  console.log('hello')
}, 2000);

const button = document.querySelector('button')
button.onclick = () => {
  clearInterval(interval)
}

to call setInterval with a callback that runs every 2 seconds.

Then we select the button with querySelector.

And we set button.onclick to a function that calls clearInterval to clear the timer.

Conclusion

To check if a setInterval timer is running and stop it with JavaScript, we can call clearIntveral with the timer variable.

Sometimes, we want to use Array.prototype.map with Promise.all in JavaScript.

In this article, we’ll look at how to use Array.prototype.map with Promise.all in JavaScript.

How to use Array.prototype.map with Promise.all in JavaScript?

To use Array.prototype.map with Promise.all in JavaScript, we should call map with a callback that returns a promise.

For instance, we write:

(async () => {
  const items = [1, 2, 3]
  const vals = await Promise.all(items.map(async (it) => it * 2))
  console.log(vals)
})()

to calls items.map with an async function as the callback.

It returns a promise that resolves to the items entry times 2.

Then we call Promise.all with the array of promises we created with map.

Therefore, vals is [2, 4, 6].

Conclusion

To use Array.prototype.map with Promise.all in JavaScript, we should call map with a callback that returns a promise.

Sometimes, we want to clone a div and change the ID’s of it and all it’s children to be unique with JavaScript.

In this article, we’ll look at how to clone a div and change the ID’s of it and all it’s children to be unique with JavaScript.

How to clone a div and change the ID’s of it and all it’s children to be unique with JavaScript?

To clone a div and change the ID’s of it and all it’s children to be unique with JavaScript, we can use the cloneNode method.

For instance, we write:

const div = document.createElement('div')
const div2 = div.cloneNode(true)
div2.id = '2'

We call cloneNode with true to do a deep clone of the div.

Then we assign a new id value to by assigning a value to the id property.

Conclusion

To clone a div and change the ID’s of it and all it’s children to be unique with JavaScript, we can use the cloneNode method.

Sometimes, we want to find event listeners on a DOM node using JavaScript.

in this article, we’ll look at how to find event listeners on a DOM node using JavaScript.

How to find event listeners on a DOM node using JavaScript?

To find event listeners on a DOM node using JavaScript, we can use the getEventListeners function in the Google Chrome dev console.

For instance, we run:

getEventListeners(document.body)

to return all the event listeners added for the body element.

Then we get something like:

{
    "click": [
        {
            "useCapture": false,
            "passive": false,
            "once": false,
            "type": "click"
        }
    ]
}

from the console log.

Conclusion

To find event listeners on a DOM node using JavaScript, we can use the getEventListeners function in the Google Chrome dev console.

Sometimes, we want to change HTML element type with JavaScript.

In this article, we’ll look at how to change HTML element type with JavaScript.

How to change HTML element type with JavaScript?

To change HTML element type with JavaScript, we can use the replaceWith method.

For instance, we write:

const parent = document.createElement("div");
const child = document.createElement("p");
parent.appendChild(child);
const span = document.createElement("span");
child.replaceWith(span);

to create a div and p element with createElement.

Then we append child as the child of the parent with appendChild.

Next, we create a span with createElement.

And finally, we call child.replaceWith with span to replace the p element with the span element as the child of the div.

Conclusion

To change HTML element type with JavaScript, we can use the replaceWith method.