Category: JavaScript Answers

Sometimes, we want to add an HTML file input that only allows a user to select only one file.

In this article, we’ll look at how to add an HTML file input that only allows a user to select only one file.

How to add an HTML file input that only allows a user to select only one file?

To add an HTML file input that only allows a user to select only one file, we can add a file input without the multiple attribute.

For instance, we write:

<input type="file" id="file" name="file" />

to add a file input that only allows us to select a single file.

Conclusion

To add an HTML file input that only allows a user to select only one file, we can add a file input without the multiple attribute.

Sometimes, we want to escape HTML with JavaScript.

In this article, we’ll look at how to escape HTML with JavaScript.

How to escape HTML with JavaScript?

To escape HTML with JavaScript, we can put the HTML string in an element.

Then we can get the escaped string from the innerHTML property.

For instance, we write:

const escapeHTML = (str) => {
  const p = document.createElement("p");
  p.appendChild(document.createTextNode(str));
  return p.innerHTML;
}
const escaped = escapeHTML('Test & Sample')
console.log(escaped)

to define the escapeHTML function that takes the str string as a parameter.

In it, we create a p element with createElement.

Then we call appendChild with the text node that we create from str with createTextNode.

Finally, we return the innerHTML property to return the escaped string.

Therefore, escaped is 'Test & Sample'.

Conclusion

To escape HTML with JavaScript, we can put the HTML string in an element.

Then we can get the escaped string from the innerHTML property.

Sometimes, we want to format numbers with commas with JavaScript.

In this article, we’ll look at how to format numbers with commas with JavaScript.

How to format numbers with commas with JavaScript?

To format numbers with commas with JavaScript, we can use the toLocaleString method.

For instance, we write:

const no = 3456;
const noStr = no.toLocaleString();
console.log(noStr)

to call toLocaleString to return a number string with digit groups separated by commas.

Therefore, noStr is '3,456'.

Conclusion

To format numbers with commas with JavaScript, we can use the toLocaleString method.

Sometimes, we want to destructure an array of objects with JavaScript.

In this article, we’ll look at how to destructure an array of objects with JavaScript.

How to destructure an array of objects with JavaScript?

To destructure an array of objects with JavaScript, we can use the array destructuring syntax.

For instance, we write:

const someArray = [{
  data: 1
}, {
  data: 2
}, {
  data: 3
}]
const [{
    data: array0
  },
  {
    data: array1
  },
  {
    data: array2
  }
] = someArray

console.log(array0, array1, array2)

to define the someArray array and get the data property values from each object with destructuring.

We assign the data property of the first someArray to array0.

And we assign the data property of the first someArray to array1.

Finally, we assign the data property of the first someArray to array2.

Therefore, console log logs 1 2 3.

Conclusion

To destructure an array of objects with JavaScript, we can use the array destructuring syntax.

Sometimes, we want to create circles around a circle with JavaScript.

In this article, we’ll look at how to create circles around a circle with JavaScript.

How to create circles around a circle with JavaScript?

To create circles around a circle with JavaScript, we can use some DOM methods.

For instance, we write:

<div id="parentDiv"></div>

to add a div.

Then we write:

const div = 360 / 6;
const radius = 150;
const parent = document.querySelector('#parentDiv')
const offsetToParentCenter = parseInt(parent.offsetWidth / 2);
const totalOffset = offsetToParentCenter;
for (let i = 1; i <= 6; ++i) {
  const childDiv = document.createElement('div');
  childDiv.className = 'div2';
  childDiv.style.position = 'absolute';
  const y = Math.sin((div * i) * (Math.PI / 180)) * radius;
  const x = Math.cos((div * i) * (Math.PI / 180)) * radius;
  childDiv.style.top = (y + totalOffset).toString() + "px";
  childDiv.style.left = (x + totalOffset).toString() + "px";
  parent.appendChild(childDiv);
}

We get the parent div with querySelector.

Then we add a for loop.

In the loop, we create a div with createElement and assign it to childDiv.

Next, we add a the class name for the childDiv.

Then we set the position of childDiv to 'absolute'.

And then we set the x and y position of the div so that they’re positioned in a circle.

Next, we call appendChild with childDiv to add them.

Finally, we add:

.div2 {
  position: absolute;
  width: 40px;
  height: 40px;
  background-color: #ac5;
  border-radius: 100px;
}

to add styles to the div.

Now we should see 6 divs arranged in a circle.

Conclusion

To create circles around a circle with JavaScript, we can use some DOM methods.