Category: JavaScript Answers

Sometimes, we want to reset all checkboxes using JavaScript.

In this article, we’ll look at how to reset all checkboxes using JavaScript.

How to reset all checkboxes using JavaScript?

To reset all checkboxes using JavaScript, we can set the checked property of each checkbox to false.

For instance, we write

const clist = document.getElementsByTagName("input");
for (const el of elist) {
  el.checked = false;
}

to select all inputs with getElementsByTagName.

Then we loop through them with a for-of loop and set each checkbox input’s checked property to false to uncheck all the checkboxes.

Conclusion

To reset all checkboxes using JavaScript, we can set the checked property of each checkbox to false.

Sometimes, we want to detect a pinch with JavaScript.

In this article, we’ll look at how to detect a pinch with JavaScript.

How to detect a pinch with JavaScript?

To detect a pinch with JavaScript, we listen to the gestureend event.

For instance, we write

node.addEventListener(
  "gestureend",
  (e) => {
    if (e.scale < 1.0) {
      //...
    } else if (e.scale > 1.0) {
      //...
    }
  },
  false
);

to listen to the gestureend event with addEventListener.

In it, we check the e.scale value.

If it’s less than 1, then the we moved our fingers closers together.

Otherwise, we moved our fingers farther apart.

Conclusion

To detect a pinch with JavaScript, we listen to the gestureend event.

Sometimes, we want to remove HTML element styles via JavaScript.

In this article, we’ll look at how to remove HTML element styles via JavaScript.

How to remove HTML element styles via JavaScript?

To remove HTML element styles via JavaScript, we can remove the style attribute from the element.

To do this, we write

element.removeAttribute("style");

to call element.removeAttribute to remove the style attribute from the element.

Conclusion

To remove HTML element styles via JavaScript, we can remove the style attribute from the element.

Sometimes, we want to make HTML element resizable using JavaScript.

In this article, we’ll look at how to make HTML element resizable using JavaScript.

How to make HTML element resizable using JavaScript?

To make HTML element resizable using JavaScript, we can listen to the mousemove event.

For instance, we write

const div = document.querySelector(`div.before`);
const box = document.querySelector(`div.container`);
box.addEventListener(`mousemove`, (e) => {
  const { offsetX, offsetY } = e;
  div.style.width = offsetX + `px`;
});

to select the div we want to resize with

const div = document.querySelector(`div.before`);

Then we select its container with

const box = document.querySelector(`div.container`);

Next, we listen to the mousemove event with addEventListener.

In the event listener, we set the width of the div to the horizontal mouse position.

Conclusion

To make HTML element resizable using JavaScript, we can listen to the mousemove event.

Sometimes, we want to test if a URL string is absolute or relative with JavaScript.

In this article, we’ll look at how to test if a URL string is absolute or relative with JavaScript.

How to test if a URL string is absolute or relative with JavaScript?

To test if a URL string is absolute or relative with JavaScript, we use a regex.

For instance, we write

const r = new RegExp("^(?:[a-z]+:)?//", "i");
const isUrl = r.test("http://example.com");

to create a regex with the RegExp constructor.

We use ^(?:[a-z]+:)?// to check for the protocol part of the URL in our string.

And use i to check the string in a case insensitive manner.

Then we call r.test to check "http://example.com" is an absolute URL.

Conclusion

To test if a URL string is absolute or relative with JavaScript, we use a regex.