Author: John Au-Yeung

Sometimes, we want to compare JavaScript sets for equality.

In this article, we’ll look at how to compare JavaScript sets for equality.

How to compare JavaScript sets for equality?

To compare JavaScript sets for equality, we can check if 2 sets have all the same entries and have the same size.

For instance, we write

const a = new Set([1, 2, 3]);
const b = new Set([1, 3, 2]);

const areSetsEqual = (a, b) =>
  a.size === b.size && [...a].every((value) => b.has(value));

console.log(areSetsEqual(a, b));

to create 2 sets a and b.

And then we check if both sets are equal with the areSetEqual function.

In it, we check if both have the same size with

a.size === b.size 

Then we convert a to an array with the spread operator and call every on the array with a callback that check if a has all the same entries as b with has.

If they have the same size and the same entries, then they’re the same since sets can’t have duplicate values.

Conclusion

To compare JavaScript sets for equality, we can check if 2 sets have all the same entries and have the same size.

Sometimes, we want to get time in milliseconds in JavaScript.

In this article, we’ll look at how to get time in milliseconds in JavaScript.

How to get time in milliseconds in JavaScript?

To get time in milliseconds in JavaScript, we can use the + operator with new Date().

For instance, we write

const currentTime = +new Date();

to create a new Date object with the current date and time with new Date().

Then we convert the current date and time to the timestamp in milliseconds by putting + before it.

Conclusion

To get time in milliseconds in JavaScript, we can use the + operator with new Date().

Sometimes, we want to create JSON object dynamically via JavaScript.

In this article, we’ll look at how to create JSON object dynamically via JavaScript.

How to create JSON object dynamically via JavaScript?

To create JSON object dynamically via JavaScript, we can create the object we want.

Then we call JSON.stringify to convert the object into a JSON string.

For instance, we write

let sitePersonnel = {};
let employees = [];
sitePersonnel.employees = employees;
console.log(sitePersonnel);

let firstName = "John";
let lastName = "Smith";
let employee = {
  firstName,
  lastName,
};
sitePersonnel.employees.push(employee);

console.log(JSON.stringify(sitePersonnel));

to create the sitePersonnel object that has various properties.

Then we call JSON.stringify to convert the sitePersonnel object into a JSON string.

Conclusion

To create JSON object dynamically via JavaScript, we can create the object we want.

Then we call JSON.stringify to convert the object into a JSON string.

Sometimes, we want to unset an element in an array in JavaScript.

In this article, we’ll look at how to unset an element in an array in JavaScript.

How to unset an element in an array in JavaScript?

To unset an element in an array in JavaScript, we call the array splice method.

For instance, we write

myArray.splice(key, 1);

to call splice with index key and 1 to remove the item in myArray at the key index.

Conclusion

To unset an element in an array in JavaScript, we call the array splice method.

Sometimes, we want to find the size of localStorage with JavaScript.

In this article, we’ll look at how to find the size of localStorage with JavaScript.

How to find the size of localStorage with JavaScript?

To find the size of localStorage with JavaScript, we can convert it to a blob and get its size.

For instance, we write

const size = new Blob(Object.values(localStorage)).size;

to convert the localStorage object to a blob with

Blob(Object.values(localStorage))

Then we get the size of the blob with the size property.

Conclusion

To find the size of localStorage with JavaScript, we can convert it to a blob and get its size.