Category: JavaScript

Sometimes, we want to check if an array has duplicate values with JavaScript.

In this article, we’ll look at how to check if an array has duplicate values with JavaScript.

How to check if an array has duplicate values with JavaScript?

To check if an array has duplicate values with JavaScript, we can use sets.

For instance, we write

const hasDuplicates = (array) => {
  return new Set(array).size !== array.length;
};

to convert array to a set with the Set constructor.

Then we check that its size isn’t the same as the array‘s length to see if it has any duplicates.

If it has duplicate values, then the set created from array won’t have the same size as the original array.

Conclusion

To check if an array has duplicate values with JavaScript, we can use sets.

Sometimes, we want to copy to clipboard in Node.js.

In this article, we’ll look at how to copy to clipboard in Node.js.

How to copy to clipboard in Node.js?

To copy to clipboard in Node.js, we use the clipboardy library.

To install it, we run

npm install clipboardy

Then we write

const clipboardy = require('clipboardy');

clipboardy.writeSync('hello world');

clipboardy.readSync();

to call clipboardy.writeSync to write 'hello world' to the clipboard.

And we call readSync to read the content of the clipboard.

Conclusion

To copy to clipboard in Node.js, we use the clipboardy library.

Sometimes, we want to get distance between two points in canvas with JavaScript.

In this article, we’ll look at how to get distance between two points in canvas with JavaScript.

How to get distance between two points in canvas with JavaScript?

To get distance between two points in canvas with JavaScript, we can use the Math.hypot method.

For instance, we write

const distance = Math.hypot(endX - startX, endY - startY);

to call Math.hypot with difference of the x and y coordinates between the start and end points.

We get the x-coordinate difference with endX - startX.

And we get the y-coordinate difference with endY - startY.

Conclusion

To get distance between two points in canvas with JavaScript, we can use the Math.hypot method.

Sometimes, we want to detect when the mouse leaves the window with JavaScript.

In this article, we’ll look at how to detect when the mouse leaves the window with JavaScript.

How to detect when the mouse leaves the window with JavaScript?

To detect when the mouse leaves the window with JavaScript, we listen for the documentElement‘s mouseenter and mouseleave events.

For instance, we write

document.documentElement.addEventListener("mouseleave", () =>
  console.log("out")
);
document.documentElement.addEventListener("mouseenter", () =>
  console.log("in")
);

to call document.documentElement.addEventListener to listen for the mouseleave and mouseenter events.

If mouseleave event is triggered on documentElement then the mouse left the window.

If mouseenterevent is triggered on documentElement then the mouse comes into the window.

Conclusion

To detect when the mouse leaves the window with JavaScript, we listen for the documentElement‘s mouseenter and mouseleave events.